How to On Delay Timer Assembly Test

Procedure to Test the On Delay Timer Assembly

The engine start switch must be in the ON position, and the air conditioning switch must be activated in order to diagnose a faulty on delay timer assembly for the refrigerant compressor.

Note: The on delay timer assembly will delay the power supply to the compressor clutch coil for 30 seconds after the air conditioning switch is activated.

1. Separate the four-pin connector from the wiring harness.
2. In order to check that power is getting from the on delay timer to the compressor, perform the following steps:

1. Set the 146-4080 Digital Multimeter Gp to DC voltage.

2. Connect the multimeter's positive probe to pin 4 on the wiring harness.

3. Connect the multimeter's negative probe to a suitable ground. The multimeter should read 24VDC for 24 volt machines. The multimeter should read 12VDC for 12 volt machines.

Note: On a 24 volt system, if the voltage is below 18VDC or if the voltage is above 32VDC, the on delay timer will not supply power to the compressor. On 12 volt systems, the range is 9VDC to 24VDC.

3. Set the 146-4080 Digital Multimeter Gp to OHMS. Connect the multimeter's positive probe to pin location 2 on the wiring harness. Connect the multimeter's negative probe to a suitable chassis ground. The multimeter will display "OL" if the ground is not present.

4. Set the 146-4080 Digital Multimeter Gp to OHMS. Connect the multimeter's positive probe to pin location 1 on the wiring harness. Connect the multimeter's negative probe to a suitable chassis ground. If the multimeter displays "OL", one of the three switches is open. If an open condition occurs, check each of the switches.

Note: There must be refrigerant in the air conditioning system in order to close both of the pressure switches.

5. In order to check that power is getting from the on delay timer assembly to the compressor clutch coil, reconnect the on delay timer assembly to the wiring harness.

1. Set the 146-4080 Digital Multimeter Gp to DC voltage.

2. Remove the 2-pin connector from the compressor clutch coil.

3. Connect the negative probe to a suitable chassis ground.

4. Check each of the two pins on the wiring harness for voltage. On a 24 volt system, one of the pins should supply 24VDC. On a 12 volt system, one of the pins should supply 12VDC.

6. In order to check the ground path from the compressor clutch coil to the chassis, perform the following steps:
1. Turn OFF the air conditioning switch in the cab.

2. Set the 146-4080 Digital Multimeter Gp to Ohms.

3. Remove the two-pin connector from the compressor clutch coil.

4. Connect the negative lead to a suitable ground.

5. Check each of the two pins on the two-pin connectors for continuity. One of the two pins should display "OL".

7. If both the correct ground and voltage are present, check the resistance of the compressor clutch coil. Refer to the Specifications section in Service Manual, SENR5664, "Air Conditioning and Heating R134a for all Caterpillar Machines", "Refrigerant Compressor".

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How to Prosedure Removed Manifold Gauge Set Refrigerant

Manifold Gauge Set (Refrigerant)

Remove charging hoses properly. A low system charge will result from charging hoses that are not removed correctly. In order to ensure accuracy of the refrigerant charge, the refrigerant should be removed from the charging hoses. Refer to the following steps in order to remove the refrigerant from the charging hoses:

1. Allow the compressor to continue operating. Close the valve on the high pressure side. The valve is located near the charging ports on the compressor. Disconnect the high pressure hose from the air conditioning system.

2. Open the high pressure valve and open the low pressure valve at the gauge set . The refrigerant that is in the hoses will be removed by the compressor through the low pressure hose.

3. Close the valve on the low pressure side. This valve is located near the charging ports on the compressor. Disconnect the low pressure hose from the air conditioning system. The system is now charged.

Note: After the manifold gauge set is removed, it is necessary to cap the charging valves.

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How to Test A/C Compressor Condition.

Refrigerant Compressor - Test

Identifying compressors that function is the purpose of this instruction. Compressors that function should be identified before the compressors are removed from a machine. Compressors that function should produce both high pressure and low pressure. If the compressor fails any one of Steps 3, 5, 7, or 8, then the compressor is considered to be a "failed" compressor. Please indicate the steps which were failed by the compressor in the Warranty Claim Story.

Note: If the compressor fails one of the steps, then the air conditioning system should be diagnosed in order to find the root cause of the failure. The root cause of the failure should be repaired. If the compressor is considered to be "good", then additional assistance with the diagnosis of the air conditioning system can be found in Service Manual, SENR5664, "Air Conditioning and Heating R134a for all Caterpillar Machines" or by contacting your Caterpillar dealer.



Procedures

1. Check the air filters. If the complaint of the customer is poor cooling of the cab, past experience has shown that plugged air filters can often be the cause. Most air conditioning systems have return air filters and fresh air filters. Be sure to check both the return air filters and fresh air filters.

Air Filters Checked? Yes or No.

2. Test the voltage. While the engine is running and the air conditioning is switched ON, check the voltage at the compressor. The voltage at the compressor should be a minimum of 11.5VDC for a 12VDC system or 23 volts for a 24VDC system. The routinely used electrical loads should be turned ON. For example, a lighting system which is added by the customer could cause available voltage to decrease below the minimum specification.

Voltage Checked? Yes or No.

Measured Voltage Level: ____ (volts)

Note: When the air conditioning is switched ON, for air conditioning systems with a Compressor Protection System (CPS), there is approximately a 30 second delay before a voltage signal is detected at the compressor. Air conditioning systems with CPS can be identified by the use of either the 169-7443 On Delay Timer As or the 212-2204 Air Conditioner Control Gp . In most applications, the electronic control group is located near the compressor.

3. Test the resistance. Measure resistance of the clutch coil at the compressor connector. For 12VDC models, measured resistance should be within -0.3 to +1.1 ohms of the amount which is listed in the Specifications section of Service Manual, SENR5664, "Air Conditioning and Heating R134a for all Caterpillar Machines", "Refrigerant Compressor". For 24VDC models, measured resistance should be within -1.3 to +5.5 ohms of the amount which is listed in Specification section of Service Manual, SENR5664, "Air Conditioning and Heating R134a for all Caterpillar Machines", "Refrigerant Compressor". The resistance ranges which are listed above compensate for the effect of temperature on the clutch coil. The values which are listed in the Specifications section of Service Manual, SENR5664, "Air Conditioning and Heating R134a for all Caterpillar Machines", "Refrigerant Compressor" are nominal for 20 °C (68 °F).

Resistance Checked? Yes or No.

Measured Level of Resistance: ____ (ohms)

4. Check the belt tension. For new belts and old belts, use the 144-0235 Belt Tension Gauge . For a new belt installation, the initial belt tension for a compressor which drives the system without an auto tensioning device should be 534 N (120 lb). For used belts, the belt tension should be 400 N (90 lb).

Belt Tension Checked? Yes or No.

Measured New Belt Tension: ____ (N) or (lbs)

Measured Old Belt Tension: ____ (N) or (lbs)

Note: The electrical power supply to the compressor should be switched OFF in order to perform this test.

# Test the rotation. Rotate the compressor in the direction of belt travel by turning the nut on the end of the main shaft of the compressor. Rotation should be smooth with no binding.
Rotation Checked? Yes or No.

Rotation Smooth? Yes or No.

1. Check the charge level. The air conditioning system must be correctly charged per Caterpillar specification or an incorrect diagnosis will occur. Recovering, evacuating, and recharging with clean refrigerant to the correct level is the best method of achieving the correct refrigerant charge for the system. Charging the air conditioning system must be conducted by weighing refrigerant with a calibrated scale in order to ensure accuracy. Also, be sure to replace the oil which was removed during refrigerant recovery with new oil. Reference Service Manual, SENR5664, "Air Conditioning and Heating R134a for all Caterpillar Machines", "Refrigerant Compressor" for procedures regarding refrigerant charging and capacity of Caterpillar air conditioning systems.

Charge Level Checked? Yes or No.

Volume of Oil that was Removed During Recovery: ____ (ml) or (oz)

Weight of Refrigerant Charge: ____ (Kg) or (lbs)

2. Test for low pressure. The test for low pressure should be performed with ambient temperatures of less than 30 °C (86 °F). Park the machine in an area that is not in direct sunlight. Close all cab doors and windows. Block the flow of fresh air into the cab. If the air conditioning system is so equipped, bypass the low pressure switch . Start the machine. Operate the machine at high idle. Turn ON the air conditioning. Set the cab blower on LOW. After 10 to 15 minutes of operation, measure the low-side pressure at the refrigerant compressor. If the pressure reading is less than 69 kPa (10 psi) then the suction valves of the compressor are operating correctly.

Low Pressure Checked? Yes or No.

Low Pressure Reading: ____ (kPa) or (Psig)

Note: If the cab temperature is above 25 °C (77 °F), then the cab blower may need to be set to HIGH in order to reduce the temperature before starting the procedure.

3. Test for high pressure. Start the engine and set the speed at approximately 1200 rpm. Turn ON the air conditioning. Place a sheet of cardboard over the condenser in order to block the flow of air. Limiting the flow of air over the condenser will cause the discharge pressure of the compressor to increase. Check if the discharge of the compressor is able to increase up to 2414 kPa (350 psi). Once the specified pressure is reached, immediately remove the cardboard. If the compressor passes the test, the discharge valves are operating correctly.

High Pressure Checked? Yes or No.

High Pressure Reading: ____ (kPa) or (Psig)
4. The functional test is now complete. If this test procedure results in inconclusive results, your dealership's Technical Communicator can report the problem by using the on-line Dealer Solution Network. The Dealer Solution Network will provide your Technical Communicator with additional troubleshooting support.

5. Illustrations 1 through 4 are provided as Good Air Conditioning System Practices and Troubleshooting Tips.

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How to test A/C leaking at Caterpillar Machine Product

Refrigerant Leakage - Test

CAT Product

In the middle of 1999, Caterpillar began installing dye in the refrigeration systems of Caterpillar machines. The dye is used in order to assist in identifying points of leakage in the refrigeration system.

Finding leaks and repairing leaks from refrigerant is important since the air conditioner is a closed circuit system.

The system must contain at least 0.4 kg (.88 lb) of refrigerant. Install the manifold gauge set. The manifold gauge set can determine if pressure exists in the system. A leak test can be performed if the system indicates pressure.

Note: Refrigerant vapor is heavier than air. For best results, place the black light directly below possible leaks.

Note: Leaks that are in the high pressure side of the system are more easily found if the air conditioner is operated for 5 to 10 minutes. The leak test must be performed immediately after the unit is turned OFF. The leak test for the high pressure side is performed before the pressures in the system equalize. Leaks that are in the low pressure side of the system are more easily found if the air conditioner has been turned OFF for 5 to 10 minutes. The leak test for the low pressure side is performed after the pressures in the system equalize.

1. Move the black light along possible leak points. When a leak is present, the black light will illuminate the dye that is in the refrigerant.

Note: Leaks that are indicated by the presence of dye should always be confirmed with an electronic leak detector.

2. If a leak is found in the air conditioning system, use a 4C-2964 Refrigerant Leak Detector in order to confirm the leak that was detected by the use of the black light.

3. Repair the leak In the air conditioning system and clean the area with 192-4727 Dye Cleaning Solution .

Leak Detector

The 208-1374 Refrigerant Leak Detectors are designed in order to detect leaks as small as 7.4 mL (.25 oz) per year of refrigerant in the air conditioning system. Perform the following procedure in order to determine if the system has a leak.

The system must contain at least 0.4 kg (.88 lb) of refrigerant. Install the manifold gauge set. The manifold gauge set can determine if pressure exists in the system. A leak test can be performed if the system indicates pressure.

Note: Refrigerant vapor is heavier than air. For best results, place the sensor tip directly below possible leaks.

Note: Leaks in the high pressure side of the system are more easily found if the air conditioner is operated for a few minutes. The leak test must be performed immediately after the unit is turned OFF. The leak test for the high pressure side is performed before the pressures in the system equalize. Leaks in the low pressure side of the system are more easily found if the air conditioner has been turned OFF for several minutes. The leak test for the low pressure side is performed after the pressures in the system equalize.

1. Move the sensor tip along possible leak points at a rate of one inch per second.

2. It may not be necessary to recover refrigerant if a loose fitting or a loose connection is causing a leak. Tighten the loose connection and perform the performance check procedure. If necessary, add refrigerant to the air conditioning system. Refer to the Testing and Adjusting, "Refrigerant System - Charge" section for the proper procedure.

3. If the repair of a leak calls for the removal or the replacement of a component, refer to the Service Manual, SENR5664, "Machine Preparation for Disassembly and Assembly" section in Disassembly and Assembly.

Note: Under normal conditions, R134a air conditioning systems that have P80 hoses may lose as much as 0.018 kg (0.0400 lb) of refrigerant per foot of hose per year.

Note: Refrigerants that are not approved by Caterpillar may have higher leakage rates.

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How if the machine intermittent low power

Intermittent Low Power or Power Cutout

Note: Use this procedure only if the engine does not shut down completely.

Probable Causes

* Diagnostic codes

* Event codes

* Turbocharger

* Air inlet and exhaust restrictions

* Throttle signal

* Power supply for the Electronic Control Module (ECM)

* Fuel supply

Recommended Actions

Note: If the problem only occurs under certain conditions, test the engine under those conditions. Examples of certain conditions are high engine speed, full load and engine operating temperature. Troubleshooting the symptoms under other conditions can give misleading results.

Diagnostic Codes and Event Codes

Certain diagnostic codes and/or event codes may cause poor performance. Connect the Caterpillar Electronic Technician (ET) and check for active codes and/or for logged codes. Troubleshoot any codes that are present before continuing with this procedure.

Turbocharger

Ensure that the turbocharger is operating correctly. Periodic inspection and cleaning is recommended for the turbocharger compressor housing (inlet side).

Air Inlet and Exhaust Restrictions

Check the air inlet system for the following problems: restrictions, collapse and pinched line. Repair the lines and/or replace the lines.

Check for an air filter restriction. Replace plugged air filters and/or clean filters. Repair any leaks.

Throttle Signal

Monitor the status for "Throttle Position" on Cat ET. Verify that the status for "Throttle Position" is stable and that the engine is able to reach high idle speed. Refer to the appropriate diagnostic test for your application:

* Troubleshooting, "Throttle Position Sensor Circuit - Test"

* Troubleshooting, "Throttle Switch Circuit - Test"

* Troubleshooting, "Speed Control - Test"

ECM Power Supply

1. Inspect the circuit between the ECM and the batteries. Refer to the Electrical System Schematic. Inspect the wires, the connectors, and the components in the circuit. Refer to the diagnostic functional test Troubleshooting, "Electrical Power Supply Circuit - Test" for more information.

2. Inspect the circuit between the ECM and the keyswitch. Refer to the Electrical System Schematic. Inspect the wires, the connectors, and the components in the circuit. Refer to the diagnostic functional test Troubleshooting, "Electrical Power Supply Circuit - Test" for more information.

Fuel Supply

1. Check the fuel lines for the following problems: restrictions, collapsed lines and pinched lines. If problems are found with the fuel lines, repair the lines and/or replace the lines.

2. Check the fuel tank for foreign objects which may block the fuel supply.

3. Prime the fuel system if any of the following procedures have been performed:

* Replacement of the fuel filters

* Service on the low pressure fuel supply circuit

* Replacement of unit injectors

Note: A sight glass in the low pressure supply line is helpful in diagnosing air in the fuel. For more information, refer to Systems Operation/Testing and Adjusting, "Air in Fuel - Test".

4. Cold weather adversely affects the characteristics of the fuel. Refer to the Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold weather operation.

NOTICE

Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again.

5. Check the fuel pressure after the fuel filter while the engine is being cranked. Refer to Systems Operation/Testing and Adjusting, "Fuel System" for the correct pressure values. If the fuel pressure is low, replace the fuel filters. If the fuel pressure is still low, check the following items: fuel transfer pump, fuel transfer pump coupling and fuel pressure regulating valve. Refer to Systems Operation/Testing and Adjusting for more information.

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How to fix if the steering problem

Testing and Adjusting
784C and 785C Off-Highway Truck/Tractors Steering System


Steering System Troubleshooting

When a problem with the steering system is defined, use the following procedure:

1. Perform a visual inspection. Refer to Testing and Adjusting, "Visual Inspection".

2. If the problem has not been identified, do "Operation Checks".

3. If the problem is still undetermined, do "Performance Tests".

This procedure will help to identify the steering hydraulic system problems.
Operation Checks

The front wheels must be on a dry, smooth hard surface and the hydraulic oil in the steering system must be warm.

Start the machine. In first gear, slowly drive the machine while you turn the steering wheel. Drive the machine until the hydraulic oil temperature is approximately 65°C (150°F).

Test the steering system with the engine at high idle. Rotate the steering wheel. Measure the time that is required to turn the front wheels from the full right turn position to the full left turn position and back to the full right turn position. If the time is more than 9.0 seconds, there could be a problem in the steering hydraulic system. If the time is less than 7.0 seconds, there could be a problem in the steering hydraulic system.

Failures in the steering system can be at least one of the following items:

* Broken oil line or a leak in an oil line connection
* Worn hydraulic oil pump
* Pressure setting of the backup relief valve
* Worn steering metering pump
* Pressure setting of steering crossover relief valve
* Leaking steering crossover relief valve
* Worn steering cylinders
* Improperly charged accumulators
* Pressure setting of the pressure and flow compensator valve

Performance Checks

Performance checks of the steering system can be used for the following purposes:

* Diagnosis of poor performance
* Source of oil leakage inside the hydraulic system

Problem: Noisy steering pump
Probable Cause

* Air in the steering hydraulic circuit
* Loose connection of the oil line on the inlet side of the pump
* Low oil level in the steering hydraulic tank
* Wrong oil viscosity

Problem: Too much force is required to turn the steering wheel.
Probable Cause

* Open backup relief valve
* Low oil in the steering hydraulic tank
* Low oil pressure in the accumulator
* Worn pump
* Tight end cover on the steering metering pump
* Interference of components on steering column with shaft
* Improper operation of steering metering pump
* Improper operation of steering crossover relief valve
* Cold oil
* Restriction in the steering linkage
* The solenoid that is located on the steering solenoid and relief valve is bad.

Problem: The machine does not turn when the steering wheel is turned.
Probable Cause

* Air in system
* Malfunction in steering crossover relief valve
* Lack of oil in steering metering pump
* Worn steering metering pump
* Disengaged steering column shaft from steering metering pump

Problem: Erratic steering
Probable Cause

* Air in system
* Worn steering linkage
* Worn cylinder piston
* Loose cylinder piston
* Malfunction of steering crossover relief valve
* Incorrect timing of steering metering pump

For proper assembly of the steering metering pump, refer to System Operation, "Metering Pump (Steering)".

Problem: The machine turns too slowly in both directions.
Probable Cause

* Not enough oil flow from the steering pump
* Malfunction of steering crossover relief valve
* Failed accumulator

Problem: The machine turns too slowly in one direction.
Probable Cause

* Restriction in steering metering pump
* Malfunction of steering crossover relief valve

Problem: The steering wheel does not return to the center position correctly.
Probable Cause

* Tight cover on steering metering pump
* Interference of components on steering column with shaft
* Restriction between spool and sleeve in steering metering pump
* Damaged centering springs in steering metering pump
* Broken centering springs in steering metering pump

Problem: Hot oil temperature
Probable Cause

* The steering pump does not destroke.
* Wrong oil viscosity
* Air in the oil
* Low oil in the steering hydraulic tank
* Low pressure setting on the backup relief valve
* Restriction in the line circuit
* Oil leakage by the solenoid in the steering solenoid and relief valve.

Problem: Low oil pressure
Probable Cause

* Low pressure setting on the pressure and flow compensator valve
* Worn steering pump
* The solenoid that is located on the steering solenoid and relief valve is bad.

Problem: The steering wheel turns freely.
Probable Cause

* The sleeve and the spool in the steering metering pump stick due to foreign material.
* Broken centering springs in the steering metering pump
* Damaged centering springs in the steering metering pump
* Incorrect timing of steering metering pump

For proper assembly of the steering metering pump, refer to System Operation, "Metering Pump (Steering)".

Problem: The steering pump does not destroke.
Probable Cause

* High pressure setting of pressure and flow compensator valve
* Damaged steering pump

Problem: Soft steering
Probable Cause

* Air in the steering hydraulic circuit
* Low oil level in tank
* Nitrogen in the steering hydraulic system from a failed accumulator

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What is a Tractors Power Train

Systems Operation
784C, 785C and 785C HAA Off-Highway Truck/Tractors Power Train

Basic diagram for the power train systems

The power train is made up of four basic systems. The following systems are the four systems:

* Power Train Electronic Control Module

* Torque Converter

* Transfer Gears and Transmission

* Differential and Final Drives

The four basic systems have a hydraulic connection, an electrical connection, a magnetic connection, or a mechanical connection.

Power is supplied from the engine to the torque converter. Power goes from the torque converter to the transfer gears. The power then goes to the transmission. If the transmission is in gear power flows from the transmission to the differential. The rear axles mechanically connect the differential to the final drives. The final drives are connected to the rear wheels. Power is then sent to the tires.

The operation of the power train begins at the Power Train Electronic Control Module (Power Train ECM). The Power Train ECM receives information of the selected speed of operation through the shift lever switch in the electrical system. The Power Train ECM uses the information from several switches and sensors in the electrical system to control the torque converter and the transmission hydraulic system. This is done by energizing the appropriate solenoids.

The rotating housing of the torque converter is fastened directly to the engine flywheel. The torque converter has a lockup clutch for direct drive and a one-way clutch for torque converter drive. During torque converter drive, the torque converter drives the transmission hydraulically. During direct drive, there is a direct connection between the engine flywheel and the transmission.

The Power Train ECM will activate the lockup clutch solenoid when direct drive is necessary. When the lockup clutch solenoid is activated, the lockup clutch is hydraulically engaged. The lockup clutch becomes a direct connection between the rotating housing and the output shaft of the torque converter. The full power from the engine flywheel is transmitted through the torque converter when the torque converter is in direct drive.

The output shaft of the torque converter is connected to a drive shaft. The drive shaft mechanically connects the torque converter to the transfer gears. The transfer gears are fastened directly to the transmission.

The Power Train ECM will activate the upshift solenoid or the downshift solenoid when shifts are needed. The upshift solenoid and the downshift solenoid hydraulically activate the rotary actuator of the transmission. Movement of the rotary actuator mechanically selects the position of the rotary selector spool. The flow through the rotary selector spool hydraulically activates the correct valves in the pressure control valve. These valves engage the correct transmission clutches. The transmission clutches mechanically connect the transmission input shaft to the output shaft and to the differential.

When the rotary selector spool is in the position to engage the correct transmission clutches, the transmission gear switch will electronically signal the Power Train ECM that the shift is complete. The Power Train ECM will stop energizing the upshift solenoid or the downshift solenoid.

When the output shaft of the transmission is rotating, the transmission speed sensor electrically signals the Power Train ECM that the machine has moved.

The transmission will not drive the output shaft unless power is flowing through the torque converter. The power that is flowing through the torque converter can be hydraulic or mechanical.

The transmission has six forward speeds and one reverse speed. The selection of reverse, neutral, or first speed is done manually. The selection of second speed through sixth speed is done automatically.

When the transmission is in reverse gear, the torque converter will stay in torque converter drive. When the transmission is in first gear, the torque converter will be in either torque converter drive or direct drive. This is dependent on ground speed. When the transmission is in any of the gears between the second gear and the sixth gear, the torque converter will be in direct drive. The torque converter will be in torque converter drive for a short time during transmission shifts. This provides smoother engagement of the transmission clutches.

The transmission output shaft is fastened directly to the differential and the bevel gear. The differential and the bevel gear are fastened directly to the rear axles. The rear axles mechanically connect the differential to the final drives. The final drives are connected to the rear wheels. Power is then sent to the tires.

The torque converter has a hydraulic system that uses oil that is also common with the brake cooling system, the parking brake release system, and the body hoist system. These systems use the same section of the hydraulic tank.

Some of the components in the torque converter hydraulic system include a torque converter inlet relief valve, a torque converter outlet relief valve, a torque converter, parking brake release, and brake cooling gear pump, a torque converter hydraulic filter, and a torque converter lockup clutch and synchronizing valve.

Pressure oil that will engage the lockup clutch comes from the parking brake release section of the torque converter and parking brake release gear pump. Oil will go through the parking brake release hydraulic filter to a tee at the parking and secondary brake valve. Some of the oil will be sent to the torque converter lockup clutch and synchronizing valve. When the torque converter lockup clutch and synchronizing valve gets a pressure signal from the lockup solenoid, pump oil from the parking brake release pump section will be sent through the torque converter lockup clutch and synchronizing valve. This oil engages the torque converter lockup clutch.

Oil from the torque converter charging pump section goes through the torque converter hydraulic filter. This oil is split. Some of the oil is sent to the pump drive for lubrication. Most of the oil goes through the torque converter inlet relief valve and into the torque converter. Oil exits the torque converter and flows through the torque converter outlet relief valve. Oil from the outlet relief valve is sent to the torque converter and front brake cooling screen.

The oil from the torque converter and front brake cooling screen goes to the torque converter and front brake cooling diverter valve. The diverter valve will direct the oil through the torque converter and front brake cooling oil cooler or the diverter valve will divert the oil around the oil cooler. The cooling oil is then sent to the front wheel brakes. The oil that cools the front wheel brakes returns to the torque converter, hoist, and brake section of the hydraulic tank.

The torque converter scavenge pump section pulls oil from the bottom of the torque converter housing through a screen. This oil is returned to the torque converter, hoist, and brake section of the hydraulic tank.

The transmission has a separate hydraulic system. The transmission will use oil from the transmission section of the hydraulic tank. Other components in this system include a transmission hydraulic control, a transmission gear pump, a transmission charging hydraulic filter, a transmission lubrication hydraulic filter, a transmission magnetic screen, and a transmission oil cooler.

The transmission charging section of the transmission gear pump sends oil through the transmission charging hydraulic filter. The oil from the transmission charging pump section then goes to the transmission hydraulic control. The basic components of the transmission hydraulic control are the rotary actuator, the selector and pressure control valve, and the pressure control valve. This oil also supplies the lockup clutch solenoid, the upshift solenoid, and the downshift solenoid.

The solenoids connect the electrical systems and the hydraulic systems. When the lockup clutch solenoid is activated, signal oil is sent to the relay valve in the torque converter lockup clutch and synchronizing valve and Station D in the pressure control valve. Signal oil that is sent to the relay valve in the lockup clutch and synchronizing valve causes the torque converter lockup clutch to engage. Oil that is going to Station D in the pressure control valve is sent to the dual stage relief valve in the selector and pressure control valve. This lowers the setting of the dual stage relief valve. The dual stage relief valve controls the system pressure in the transmission hydraulic control.

When the upshift solenoid or the downshift solenoid is activated, oil is sent to the rotary actuator. The rotary actuator turns the rotary selector spool in the selector and pressure control valve. This sends oil to the pressure control valve. The pressure control valve sends oil at the correct rate so that the correct clutches in the transmission are engaged smoothly.

The rotary selector spool can be manually moved through all the positions when the engine is stopped. This is done by removing a plug on the side of the transmission case. The rotary selector spool is in the NEUTRAL-1 position when the spool is turned manually in a clockwise direction to the farthest point. The counterclockwise order of each detent position after the NEUTRAL-1 position is NEUTRAL-2, REVERSE, FIRST, SECOND, THIRD, FOURTH, FIFTH, and SIXTH. The SEVENTH speed and the EIGHTH speed are not used on this machine.

The transmission lubrication section of the transmission gear pump sends oil to the transmission lubrication hydraulic filter. This oil combines with oil from the dual stage relief valve. The dual stage relief valve is located in the selector and pressure control valve which is part of the transmission hydraulic control. The combined oil is sent to the transmission oil cooler. This oil is then used to lubricate the transmission and the transfer gears. The transmission lubrication relief valve controls the pressure of this oil system. If the pressure is too high the transmission lubrication relief valve will dump oil to the transmission case reservoir.

The transmission scavenge section of the transmission gear pump pulls oil from the transmission case reservoir. This oil goes through the transmission magnetic screen. The oil then returns to the transmission section of the hydraulic tank.

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ECM for control engine governor and fuel injection type D10R

Diagram fuel injection and electronic governor



The electronic system consists of the following components: Electronic Control Module (ECM), Hydraulic Electronic Unit Injectors (HEUI), Injection Actuation Pressure Control Valve (IAPCV), wiring harness, switches and sensors. The ECM receives information from the sensors and the switches on the engine. The ECM processes the information that is collected in order to make decisions on control of the engine. By altering the fuel delivery of the injectors, the ECM controls the speed and the power that is produced by the engine.
Electronic Control System

The ECM consists of two main components:

* Control computer (hardware)
* Personality module (software)

Personality module

The control computer is the microprocessor and the electronic circuitry. The personality module contains the software for the control computer. The software contains operating maps that define the following characteristics of the engine:

* Horsepower
* Torque curves
* Engine speed

Engine Governor.

The ECM governs the engine speed by controlling the amount of fuel that is delivered by the injectors. Refer to Illustration 2. The desired engine speed is determined by input from the throttle switch. Actual engine speed is measured by the engine speed/timing sensors. The ECM changes the amount of fuel that is injected until the actual engine speed matches the desired engine speed.

Fuel Injection.

The ECM controls the timing, the duration, and the pressure of the fuel that is injected. The ECM controls the timing and the duration by varying the signals to the injectors. The injectors will inject fuel only if the injector solenoid is energized by a 105 volt signal from the ECM. By controlling the timing and the duration of the 105 volt signal, the ECM can control the timing of the injection and the ECM can control the amount of fuel that is injected. The ECM modulates the injection pressure by varying the signal to the Injection Actuation Pressure Control Valve (IAPCV). The IAPCV controls the pressure of the high pressure oil. The high pressure oil pressurizes the fuel that is in the injectors. By controlling the signal to the IAPCV, the ECM controls the pressure of the fuel that is injected into the engine.

The ECM limits engine power and the ECM modifies injection pressure and injection timing during Cold Mode operation. Cold Mode operation has the following benefits: increased startability, reduced warm up period and reduced white smoke. Cold Mode is active if the engine oil temperature falls below a predetermined value and other conditions are met. Cold Mode remains active until the engine has warmed or until a time limit has been exceeded.

The personality module inside the ECM sets certain limits on the amount of fuel that can be injected. The FRC Limit is a limit that is based on the boost pressure. The boost pressure is calculated as the difference in pressure between atmospheric pressure and turbocharger outlet pressure. The FRC Limit is used to control the air/fuel ratio for control of emissions. When the ECM senses a higher boost pressure, the ECM increases the FRC Limit. A higher boost pressure indicates that there is more air in the cylinder. When the ECM increases the FRC Limit, the ECM allows more fuel into the cylinder.

The Rated Fuel Position is a limit that is based on the power rating of the engine. The Rated Fuel Position is similar to the rack stops and the torque spring on a mechanically governed engine. The Rated Fuel Position determines maximum power and torque values for a specific engine family and a specific rating. The Rated Fuel Position is programmed in the personality module at the factory.
Programmable Parameters

System configuration parameters are parameters that are stored in the ECM. The stored parameters affect engine operation. The parameters are set at the factory. The parameters may be changed by using an electronic service tool. However, a factory password may be required to change certain parameters.
Passwords

Several parameters and most logged events are protected by factory passwords. Factory passwords are available only to Caterpillar dealers.

Note: Refer to Troubleshooting, "Factory Passwords" for information, if factory passwords are needed.

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Starting motor 50-MT

Starting motor 50-MT


The 50-MT series starting motor may be ordered in the following versions: 24 volt, 32 volt and 64 volt. See the chart in Specifications, "50-MT Series Starting Motor Coverage" for a list of part numbers for starting motors that are covered in this module.

The starting motor is used in order to turn the engine flywheel quickly in order to allow the engine to run. The starting motor has a solenoid assembly. When the key start switch is activated, electricity from the electrical system will cause the solenoid to move the pinion drive assembly toward the flywheel ring gear of the engine. The electrical contacts in the solenoid close the circuit between the battery and the electric starting motor just before the pinion engages the ring gear. This causes the starting motor to rotate. This type of motor "activation" is referred to as a positive shift starting motor.

When the engine begins to run, the overrunning clutch of the pinion drive assembly prevents damage to the armature by breaking the mechanical connection. The pinion will stay meshed with the ring gear until the key start switch is released. A return spring in the overrunning clutch returns the clutch to the rest position.

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How to Calibrate Engine Pressure Sensor for CAT- D10R

Engine Pressure Sensor - Calibrate


System Operation Description:

The Electronic Control Module (ECM) attempts to perform an automatic calibration of all pressure sensors whenever the ECM is powered and the engine is OFF for at least five seconds. Cranking the engine during the first five seconds causes the ECM to abort the calibration attempt. Perform a manual calibration if a pressure sensor is replaced.

During an automatic pressure sensor calibration, the ECM checks all pressure sensors against an acceptable range. If any pressure sensor reading is outside the acceptable range, the previous calibration value is used. The ECM then calibrates all pressure sensors against the atmospheric pressure sensor.

During a manual pressure sensor calibration, the ECM checks the signal from the atmospheric pressure sensor against an acceptable range of pressures. The ECM then calibrates the remaining analog pressure sensors against the atmospheric pressure sensor. The ECM also uses an offset value to calibrate the remaining analog sensors. A diagnostic code with an FMI - 13 "Calibration Required" is generated if the value of the offset is not within an acceptable range.

A pressure sensor calibration will not be successful if there are any active diagnostic codes for pressure sensors with an FMI - 03 "open/short to +batt" or an FMI - 04 "short to ground".

Test Step 1. Check for Active Diagnostic Codes

1. Turn the keyswitch to the OFF/RESET position.
2. Connect the Caterpillar Electronic Technician (Cat ET) to the data link connector.
3. Turn the keyswitch to the ON position.
4. Check for active diagnostic codes.

Expected Result:

There are no active diagnostic codes.

Results:

* OK - Proceed to Test Step 2.
* Not OK - A pressure sensor with an active diagnostic code cannot be calibrated.

Repair: Perform the appropriate troubleshooting procedure for the active diagnostic code.

Repeat Test Step 1.

Test Step 2. Perform a Manual Calibration of the Sensors

1. Select "Calibrate Pressure Sensors" on Cat ET. The ECM will perform a manual pressure sensor calibration when this screen is entered.

Expected Result:

Cat ET indicates that the calibration was completed.

Results:

* OK - Cat ET indicates that the calibration was completed.STOP
* Not OK - All pressure sensors could not be calibrated. Proceed to Test Step 3.

Test Step 3. Determine the Cause of the Failed Manual Calibration

1. Check if any pressure sensors have FMI - 13 "calibration required" in order to determine the sensor that is not functioning correctly.
2. Verify that the correct sensor has been installed.
3. Check the "Status" screen on Cat ET for the pressure sensor reading.
4. Turn the keyswitch to the OFF/RESET position.
5. Record the barometric pressure in your area from a valid source.

Expected Result:

Offset values:

* The turbocharger compressor inlet pressure does not differ from atmospheric pressure by more than 8 kPa (1.1 psi).
* The turbocharger outlet pressure does not differ from atmospheric pressure by more than 15 kPa (2.0 psi).
* The engine oil pressure does not differ from atmospheric pressure by more than 27 kPa (4.0 psi).
* The atmospheric pressure does not differ from actual barometric pressure by more than 5 kPa (0.7 psi).

Results:

* OK - Repeat manual calibration of the sensors.STOP

Not OK - There is a problem with the wiring harness and/or the sensor. Inspect the components for damage, corrosion, and abrasion. Repair the components and/or replace the components. Repeat Test Step 1.

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How to Check step by step Refrigerant Circuit Problems part 9

Refrigerant Circuit Problems

System Condition 14

1. Low pressure gauge reading is below normal. For normal operating pressures, refer to Table 1.

2. High pressure gauge reading is below normal. For normal operating pressures, refer to Table 1.

Note: Ambient temperature is above 21°C (70°F).

3. The air flow to the operator's compartment is very cold, or the air flow may be restricted completely at times.

Probable Cause

The thermostat switch is held closed. There is a short in the wire to the magnetic clutch. The magnetic clutch will not release.

* Check the wire that goes to the magnetic clutch. The wire may have an electrical short.

* Replace the thermostat switch.

* Make the necessary repairs to the magnetic clutch.

Additional Refrigerant Circuit Problems for Orifice Tube System

System Condition 15

The compressor clutch is engaged but the system has insufficient cooling.

Probable Cause

* The system is improperly charged.

* A compressor drive belt that is loose or a compressor drive belt that is worn can cause insufficient cooling.

* Restrictions, insects, foreign material in the condenser, or any restriction of air flow can cause insufficient cooling.

* A missing or a plugged orifice tube can cause insufficient cooling.

* A restriction in a liquid line or a low amount of refrigerant charge can cause insufficient cooling.

1. Install the manifold gauge set. Refer to the Service manual, SENR5664, "Manifold Gauge Set (Refrigerant) - Install" section.

2. Start the engine. Operate the engine at 1400 rpm. Move the temperature control knob to the Maximum position and the fan to the High position. Close all windows and doors. In order to stabilize the system, operate the system for a minimum of ten minutes.

Note: Ambient temperature is above 21°C (70°F).

3. The outlet on the accumulator should be cold to the touch. If the outlet is not cold, check the readings on the manifold gauges.

* If the low side reading is above 345 kPa (50 psi), check for a missing orifice tube. Refer to Service Manual, SENR5664, "Orifice Tube (Air Conditioner) - Remove and Install" in Disassembly and Assembly.

* If the low side reading is into vacuum, check for a plugged orifice tube or a restriction in the line.

* A restriction in the liquid line can be detected by running a hand along the line until there is a change in temperature. A change in temperature in the line will usually indicate the location of the restriction.

4. If the inlet and the outlet on the accumulator are warm, refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting. Also, refer to the Service Manual, SENR5664, "Refrigerant Leakage-Test" section in Testing and Adjusting.

False Seizure of the Compressor

Table Required Tools

Part Number = 1U-8590
Part Description = Spanner Wrench

On the initial start-up of the air conditioner system, slipping drive belts and broken drive belts may be experienced if the air conditioner system has not been used for an extended period of time. Also, scored clutch surfaces may be experienced. This would indicate a seized compressor. However, replacement of the compressor may not be necessary.

Changes in temperature can cause expansion of the refrigerant in the compressor during extended periods of nonuse. Also, changes in temperature can cause contraction of the refrigerant in the compressor during extended periods of nonuse. During this movement, lubricating oil that is carried by the refrigerant migrates. The lubricating oil moves away from highly polished surfaces in the compressor. Without lubricating oil at the polished surfaces, the polished surfaces rub together. This can appear as a seized compressor.

The compressor should be checked for seizure before the compressor is replaced. Use the procedures that follow in order to check the compressor for seizure.

1. With a spanner wrench on the clutch drive plate, rock the shaft in the opposite direction of normal rotation.

2. After the clutch drive plate is movable, rotate the clutch drive plate at least three complete revolutions in the counterclockwise direction.

3. Start the engine. Operate the compressor for a minimum of one minute.

This procedure will not correct a seized compressor. However, this procedure should be attempted before you replace a compressor that has been idle for a month or longer.

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How to check step by step Refrigerant Circuit Problems part 8

Refrigerant Circuit Problems

System Condition 12

* Water is in the vents.

* Water is leaking from the unit.

Probable Cause

* The non-return valve of the drain

1. Check the non-return valve for proper positioning and proper direction.

The Compressor will not Engage

If the machine is equipped with the protection system for the refrigerant compressor, Refer to the Service Manual, SENR 5664, "Troubleshooting Heating and Air Conditioning Control Systems" in order to test the on delay timer assembly for the refrigerant compressor.

System Condition 13

1. Low pressure gauge reading is above normal.

2. High pressure gauge reading is below normal.

Note: Ambient temperature is above 21°C (70°F).

3. Air flow to the operator's compartment is warm.

Probable Cause

1. The thermostatic switch is stuck open. This does not allow the magnetic clutch to cycle the compressor.

1. Check the wire connectors on the thermostatic switch and on the magnetic clutch.

2. The connection of wire leads on switch is improper. The connection of wire leads on the magnetic clutch is improper.

1. Check for insulation that is broken. The insulation failure can expose the wires from the switch to the magnetic clutch.

3. The wire that connects the switch to the magnetic clutch has an opening.

1. Check the resistance of the coil with a multimeter. Refer to the Service Manual, SENR5664, "Refrigerant Compressor" section in Specifications.

2. Check for the proper electrical ground at the magnetic clutch.

3. Touch the two wires on the switch together. Check for the proper operation of the magnetic clutch.

4. In order to check the electrical components, refer to Service Manual, SENR5664, "Troubleshooting Heating and Air Conditioning Control System" in Testing and Adjusting.

If the problem is a loose wire on the switch or a loose wire on the magnetic clutch, make the repairs that are needed. If the wires to the clutch were damaged, the damaged wires can cause the switch to remain open. Make the needed repairs to the damaged wires. In order to ensure the correct system operation, perform a performance check.

4. The charge of refrigerant in the capillary tube has been lost.

1. If the capillary tube has no charge or the switch remains open, the problem is in the thermostatic switch.

* Replace the switch.

* In order to ensure the correct system operation, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

The Compressor Continues to Cycle or the Clutch will not Disengage.

Note: The cause of the problem may be one of the following conditions: low charge, overcharge and evaporator freeze-up .

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How to Check step by step Refrigerant Circuit Problems part 7

Refrigerant Circuit Problems

System Condition 11

1. Low pressure gauge reading is too high.

2. High pressure gauge reading is too high.

Note: Ambient temperature is above 21°C (70°F).

3. The temperature of the air flow from the evaporator is warm.

Probable Cause

The condenser is not functioning properly.

Note: The system may have a normal or overcharge of refrigerant.

1. Check for a blockage in the flow of air through the condenser.

2. If a blockage is found in the condenser, remove all blockages and perform a performance check. The performance check will ensure proper system operation. Refer to "Performance Checks for the Air Conditioning System" section.

3. If the problem still exists, perform the following procedure. Check the system for an overcharge of refrigerant.

Note: Do not operate the engine.

* Recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section in Testing and Adjusting.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Recharge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

Note: With the ambient temperature above 21°C (70°F), the normal gauge reading for the low pressure side is 70 to 138 kPa (10 to 20 psi) while the normal gauge reading for the high pressure side is 820 to 1300 kPa (120 to 190 psi).

* In order to ensure the correct systems operation, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

4. If the low pressure gauge reading and the high pressure gauge readings are too high, perform the following procedure:

* Recover the refrigerant from the system. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section in Testing and Adjusting.

* Replace the receiver-dryer or replace the in-line dryer. Refer to the Service Manual, SENR5664, "Receiver-Dryer - Remove and Install" section in Disassembly and Assembly. For in-line dryers, refer to the Service Manual, SENR5664, "In-Line Refrigerant Dryer - Remove and Install" section in Disassembly and Assembly.

* If the receiver-dryer or the in-line dryer is not equipped with quick couplers, evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

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How to Check step by step Refrigerant Circuit Problems part 6

Refrigerant Circuit Problems

System Condition 10
1. Low pressure gauge reading is too low.

2. High pressure gauge reading is too low.

Note: Ambient temperature is above 21°C (70°F).

3. The temperature of the air flow from the evaporator is partially cool or warm.

4. Moisture (water) or frost is on the expansion valve inlet or orifice tube assembly.

Probable Cause

The problems that are described in Step 1 through Step 4 can be caused by the following faults:

Note: The following faults will cause a restriction of the flow of refrigerant to the evaporator.

* Improper operation of the expansion valve (stuck valve)

* Blockage at the evaporator inlet

* No charge in temperature sensing bulb

Note: The inlet to the expansion valve will be warm during normal operation.

1. If the expansion valve inlet is cool to the touch, perform the following procedure:

* Position the air conditioner temperature control knob to the maximum COOL position and the fan switch to the HIGH position.

* Cool the head of the expansion valve diaphragm chamber and capillary tube with ice or liquid nitrogen. Record the low pressure gauge reading. The low pressure gauge should indicate a vacuum.

* If a vacuum is indicated on the low pressure gauge, place a hand over the expansion valve diaphragm chamber. The hand will warm the expansion valve diaphragm chamber. In order to ensure the correct operation of the expansion valve, cool the head of the expansion valve diaphragm chamber and the capillary tube with ice or liquid nitrogen again. If the operation of expansion valve is correct, refer to Step 2.

* If the low pressure gauge does not indicate proper operation of the expansion valve, remove the refrigerant from the system. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section in Testing and Adjusting.

* Replace the expansion valve. Refer to the Service Manual, SENR5664, "Expansion Valve - (Air Conditioner) Remove and Install" section in Disassembly and Assembly.

Note: The sensing bulb must be installed correctly in order to ensure the correct operation of the expansion valve. Clean the location for the sensing bulb with steel wool or emery paper. Use a 8P-6355 Clip in order to attach the sensing bulb securely to the evaporator coil outlet pipe. Completely cover the assembly with 5P-7070 Strip Insulation .

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

2. If the low pressure gauge indicates the correct operation of the expansion valve, perform the following procedure:

* The sensing bulb must be in the correct position on the evaporator outlet pipe and the sensing bulb must be the correct distance away from the evaporator outlet. The bulb should be upstream from the pressure sensing connection in the evaporator outlet pipe. The insulation must be around the sensing bulb and the clip on the evaporator outlet pipe.

* In order to ensure the correct systems operation, perform a performance check.

3. Replace the in-line dryer or replace the orifice tube.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.


Illustration can look at above

Expansion valve in the closed position (Typical Example)

(1) Capillary tube

(2) Expansion valve diaphragm chamber

(3) Inlet

(4) Outlet

Note: For expansion valve systems, refer to Step 1. For orifice tube systems, refer to Step 3.

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How to Check step by step Refrigerant Circuit Problems part 5

Refrigerant Circuit Problems

System Condition 9

1. Low pressure gauge reading is above normal. For normal operating pressures, refer to Table 1.

2. High pressure gauge reading is normal or low. For normal operating pressures, refer to Table 1.

Note: Ambient temperature is above 21°C (70°F) and the system has a refrigerant charge that is full.

3. The temperature of the air flow from the evaporator is warm.

4. The suction hose and the evaporator is covered with moisture (sweating).

Probable Cause

Flow of refrigerant through the evaporator coil is excessive. The expansion valve could be stuck or held in the OPEN position.

1. Test the expansion valve for the correct operation. Use the following procedure.

* Position the air conditioner temperature control knob in the maximum COOL position and the fan switch in the HIGH position.

* Cool the head of the expansion valve diaphragm chamber and the capillary tube with ice or liquid nitrogen. Record the low pressure gauge reading. The low pressure gauge should indicate a vacuum.

* If the low pressure gauge indicates a vacuum, place a hand over the expansion valve diaphragm chamber. The hand will warm the expansion valve diaphragm chamber. In order to ensure the correct operation of the expansion valve, cool the head of the expansion valve diaphragm chamber and the capillary tube with ice or liquid nitrogen again. If the operation of the expansion is correct, refer to Step 2.

* If the low pressure gauge does not indicate the proper operation of the expansion valve, recover the refrigerant from the system. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section in Testing and Adjusting.

* Replace the expansion valve. Refer to the Service Manual, SENR5664, "Expansion Valve - (Air Conditioner) Remove and Install" section in Disassembly and Assembly.

Note: The sensing bulb must be installed correctly in order to ensure the proper operation of the expansion valve.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

2. If the pressure gauge indicates the correct operation of the expansion valve, perform the following procedure.

* Use a 8P-6355 Clip in order to hold the sensing bulb onto the evaporator outlet pipe. The sensing bulb should be as close to the evaporator as possible. The bulb should be upstream of the pressure sensing connection on the evaporator outlet pipe. The following items must be wound tightly with 5P-7070 Strip Insulation : the clip, the sensing bulb and the outlet pipe. There should be no insulation between the bulb and the outlet pipe.

* In order to ensure that the system operates correctly, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.


Illustration can look at above

Expansion valve in the open position (Typical Example)

(1) Capillary tube

(2) Expansion valve diaphragm chamber

(3) Inlet

(4) Outlet

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How to Check step by step Refrigerant Circuit Problems part 4

Refrigerant Circuit Problems

System Condition 8

1. Low pressure gauge reading is above normal.

2. High pressure gauge reading is below normal.

Note: Ambient temperature is above 21°C (70°F) and the system has a refrigerant charge that is full.

3. The temperature of the air flow from the evaporator is partially cool.

Probable Cause

The compressor has internal leaks. The reed valve has leakage. The compressor piston, rings or cylinders are worn.

* Check the compressor drive belt for the correct tension.

* Perform a leak test. Isolate the problem to the compressor. Refer to the Service Manual, SENR5664, "Refrigerant Leakage - Test" section in Testing and Adjusting.

If an internal leak is found, perform the following procedure.

* Replace the compressor. Refer to the Service Manual, SENR5664, "refrigerant Compressor - remove and Install" section in Disassembly and Assembly.

* Replace the receiver-dryer. Refer to the Service Manual, SENR5664, "Receiver-Dryer - Remove and Install" section in Testing and Adjusting.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

If an external leak such as a hose connection is found, perform the following procedure.

* Recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Repair leaks.

If a large amount of refrigerant is lost, check the compressor for the loss of oil.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

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How to Check step by step Refrigerant Circuit Problems part 3

Refrigerant Circuit Problems

System Condition 6

1. The low pressure gauge reading does not change. The pressure should rise when the compressor is not in operation. For normal operating pressures, refer to Table 1.

2. High pressure gauge reading is at the high end of the normal range.

Note: Ambient temperature is above 21°C (70°F).

3. The temperature of the air flow from the evaporator is partially cool.

Probable Cause

The system has air or moisture in the system. The system does not have a full charge of refrigerant.

* Perform a leak test and carefully test around the compressor seal. Refer to the Service Manual, SENR5664, "Refrigerant Leakage - Test" section in Testing and Adjusting.

* Recover the refrigerant from the system. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section in Testing and Adjusting.

* Repair leaks.

* Check the compressor for loss of oil.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

System Condition 7

1. Low pressure gauge reading is above normal. For normal operating pressures, refer to Table 1.

2. High pressure gauge reading is above normal. For normal operating pressures, refer to Table 1.

Note: Ambient temperature is above 21°C (70°F).

3. High pressure (liquid line) is very hot.

4. The compressor may become noisy and the drive belt may slip.

Note: The compressor is not operating under ambient temperatures that are extreme. The compressor is not operating under high humidity that is extreme.

Probable Cause

The system is overcharged.

* Recover the remaining refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* Perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

Note: Perform the following procedure if the system has not been serviced for a extended period of time. Perform the following procedure if the pressures of the system are not within the correct specifications.

* Recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting. If service work has not been performed for a extended period of time, replace the receiver-dryer or the in-line dryer.

* Charge the system with the correct amount of refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

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How to check step by step Refrigerant Circuit Problems part 2

Refrigerant Circuit Problems

System Condition 4

1. Low pressure gauge reading is below normal. For normal operating pressures, refer to Table 1.

2. High pressure gauge reading is normal to the below normal range. For normal operating pressures, refer to Table 1.

Note: Ambient temperature is above 21°C (70°F).

3. The temperature of the air flow from the evaporator is partially cool.

4. The high side liquid line or the receiver-dryer is frosted. The high side liquid line or the receiver-dryer is cool to the touch.

Probable Cause

Restriction in the high pressure liquid line can cause the refrigerant to be removed from the evaporator at a faster rate. The restriction can cause the evaporator to be low on refrigerant from the receiver-dryer or from the in-line dryer. Clogged filters or a failure of the blower motor can cause possible restrictions to the air flow.

* Recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* If the restriction is found at the receiver-dryer, replace the receiver-dryer. Refer to the Service Manual, SENR5664, "Receiver-Dryer - Remove and Install" section in Disassembly and Assembly.

* If the restriction is found at the in-line dryer, replace the in-line dryer.

* If the restriction is found at the liquid line, replace the liquid line.

* Cap all the open lines and fittings.

Note: Restrictions of the refrigerant flow are identified by frost or cold spots in the line. Also, restrictions of the refrigerant flow are identified by frost or cold spots in the receiver-dryer or the in-line dryer.

* Replace filters or remove any of the restrictions.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

System Condition 5

Note: The system only cools the cab in the morning and in the evening. The system does not cool the cab during the hot part of the day.

1. Low pressure gauge reading is normal, but the gauge reading may drop into the vacuum range during the testing procedure. For normal operating pressures, refer to Table 1.

2. The high pressure gauge reading is normal, but the gauge reading is below normal when the low pressure gauge drops into the vacuum range. For normal operating pressures, refer to Table 1.

Note: Ambient temperature is above 21°C (70°F).

3. Air flow from the evaporator is very cold, but the air flow will become warm when the low pressure gauge drops into vacuum.

Probable Cause

The system has a large amount of moisture. The desiccant in the receiver-dryer or the in-line dryer is full of water. The water is released during high ambient temperatures. Ice collects in the orifice or the expansion valve and the ice can block the flow of refrigerant.

* Recover the refrigerant from the system. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section in Testing and Adjusting.

* Replace the receiver-dryer or the in-line dryer. Refer to the Service Manual, SENR5664, "Receiver-Dryer - Remove and Install" section in Disassembly and Assembly. For in-line dryers, refer to the Service Manual, SENR5664, "In-Line Refrigerant Dryer - Remove and Install" section in Disassembly and Assembly.

* Remove the moisture from the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

Note: Low pressure (suction) drops into vacuum when ice forms in the expansion valve. High pressure (discharge) drops when low pressure drops into vacuum.

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How to Check step by step Refrigerant Circuit Problems part 1

Refrigerant Circuit Problems

There is no or only little cool temperature to the air flow from the evaporator.

System Condition 1

1. Low pressure gauge reading is below normal. For normal operating pressures, refer to Table 1.

2. High pressure gauge reading is below normal. For normal operating pressures, refer to Table 1.

Note: Ambient temperature is above 21°C (70°F).

3. From the evaporator, the temperature of the air flow is partially cool.

Probable Cause

Leaks in the refrigerant circuit will cause the system to be low on refrigerant.

* Perform a leak test. refer to the Service Manual, SENR5664, "Refrigerant Leakage - Test" section in Testing and Adjusting.

* If leaks are found, recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Repair leaks.

* If a large amount of refrigerant was lost, it is important to check the compressor for loss of oil.

* Perform a partial charge of the system.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in testing and adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

System Condition 2

1. Low pressure gauge reading is normal. For normal operating pressures, refer to Table 1.

2. High pressure gauge reading bounces or the reading is unsteady.

Probable Cause

Air is in the system.

* Reclaim the refrigerant from the air conditioning system.

* Evacuate the air conditioning system.

* Recharge the air conditioning system.

System Condition 3

1. Low pressure gauge reading is below normal. For normal operating pressures, refer to Table 1.

2. High pressure gauge reading is above normal. For normal operating pressures, refer to Table 1.

Note: Ambient temperature is above 21°C (70°F).

3. The temperature of the air flow from the evaporator is warm.

Probable Cause

Air or moisture (water) in the system

* Recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Replace the receiver-dryer or the in-line dryer. The desiccant may be full of moisture. This will release water into the system. Refer to the Service Manual, SENR5664, "Receiver-Dryer - Remove and Install" section in Disassembly and Assembly. For in-line dryers, refer to the Service Manual, SENR5664, "In-Line Refrigerant Dryer - Remove and Install" section in Disassembly and Assembly.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* After the system is charged and operated for a minimum of ten minutes, perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

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Due Air Conditioning System Troubleshooting

Heating and Air Conditioning System Troubleshooting

Refrigerant Quick-Check Procedure for R-134a Expansion Valve And Orifice Tube Systems

Note: This procedure does not call for the installation of the manifold gauge set. The procedure should be used only as an indication of the actual system condition. For the detailed troubleshooting procedures, refer to the "Problem Solving Procedure" section.

Note: In order to use this procedure, the temperature of the ambient air must be at least 21°C (70°F).

1. Start the engine and run the engine at approximately 1000 rpm. Move the control knob on the air conditioner to the position of MAXIMUM so that cooling is at a maximum. In order to stabilize the system, put the fan switch in the HIGH position and operate the system for a minimum of 10 minutes.

For systems that have air conditioner quick disconnects, the dryer can be removed without recovering the refrigerant.

* Replace the receiver-dryer. Refer to the Service Manual, SENR5664, "Receiver-Dryer - Remove and Install" section in Disassembly and Assembly.

* Perform a leak test. Refer to the Service Manual, SENR5664, "Refrigerant Leakage - Test" section in Testing and Adjusting.

* Perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

2. Check for restrictions that are present in the refrigerant lines from the compressor to the receiver-dryer. The refrigerant lines and the components that are high pressure and high temperature come from the outlet side of the compressor. The lines go to the inlet side of the expansion valve or orifice tube. The outlet side will be warm during normal operation. Heavy frost or a decrease in the temperature in a line or in a component on the high pressure side may be an indication of a restriction or blockage.

1. If there is no evidence of a restriction in the condenser coil, the receiver-dryer or refrigerant lines from the compressor to the receiver-dryer, use the procedure in Step 3.

2. If there is a restriction in the condenser coil, the receiver-dryer or refrigerant lines from the compressor to the receiver-dryer, perform the following procedures.

* Recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Remove the restriction or replace the component.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* Perform a leak test. Refer to the Service Manual, SENR5664, "Refrigerant Leakage - Test"section in Testing and Adjusting.

* Perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

3. If frost is present on the expansion valve, check the moisture indicator on the receiver-dryer. If the indicator is pink or white, and the receiver does not have air conditioner quick disconnects, perform the following procedures.

* Recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Replace the receiver-dryer. Refer to the Service Manual, SENR5664, "Receiver-Dryer - Remove and Install" section in Disassembly and Assembly.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* Perform a leak test. Refer to the Service Manual, SENR5664, "Refrigerant Leakage - Test" section in Testing and Adjusting.

* Perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

Refer to the Service Manual, SENR5664, "Receiver-Dryer - Remove and Install" section if the receiver-dryer has air conditioner quick disconnects. Refer to the Service Manual, SENR5664, "In-Line refrigerant Dryer - Remove and Install" section if the in-line dryer has air conditioner quick disconnects.

4. On air conditioning systems that have a dryer with a moisture indicator, if the indicator is blue and the system is free of moisture, the expansion valve may be blocked.

* Recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Replace the expansion valve. Refer to the Service Manual, SENR5664, "Expansion Valve - (Air Conditioner) Remove and Install" section in Disassembly and Assembly.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* Perform a leak test. Refer to the Service Manual, SENR5664, "Refrigerant Leakage - Test"section in Testing and Adjusting.

* Perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

3. Low system charge is indicated. Perform a leak test.

Note: If the system is very low on refrigerant, a partial charge may be needed before you perform a leak test.

* Recover the remaining refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Repair all leaks.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* Perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

4. Feel the low pressure line and feel the high pressure line at the compressor. In order to indicate normal systems operation, the high pressure line to the condenser coil must be warm, while the low pressure line to the evaporator coil must be cool.

* The high pressure line and the low pressure line at the compressor have a minimal temperature difference between the two lines. Use the procedure in Step 5.

* If there is a definite temperature difference between the high pressure line and the low pressure line at the compressor, the system is operating correctly. The high pressure line will be warm. The low pressure line will be cool. Use the procedure in Step 6.

5.If the system has no refrigerant charge or if the system is nearly empty of refrigerant charge, perform the following procedure:

* Stop the engine.

* Perform a partial charge of the system.

* Perform a leak test. Refer to the Service Manual, SENR5664, "Refrigerant Leakage - Test" section in Testing and Adjusting.

* Repair leaks.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* Perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

6. An overcharge of the system is possible even though the system can have a definite difference in temperature at the low pressure line and at the high pressure line.

* Recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in Testing and Adjusting.

* Perform a performance check. Refer to the "Performance Checks for the Air Conditioning System" section.

Note: For an orifice tube system, an additional inspection is required. The additional inspection procedure determines the level of the system charge. When both the inlet of the accumulator and the outlet of the accumulator are cool to the touch, the system is charged correctly.

If the outlet is warmer than the inlet, the system may not contain enough refrigerant.

* Recover the refrigerant. Refer to the Service Manual, SENR5664, "Refrigerant Recovery" section.

* Evacuate the system. Refer to the Service Manual, SENR5664, "Refrigerant System - Evacuate" section in Testing and Adjusting.

* Charge the system with the correct amount of refrigerant. Measure the refrigerant by weight. Refer to the Service Manual, SENR5664, "Refrigerant System - Charge" section in testing and adjusting.

* Perform a leak test. Refer to the Service Manual, SENR5664, "Refrigerant Leakage - Test" section in Testing and Adjusting.

* Perform a performance check. Refer to "Performance Checks for the Air Conditioning System" section.

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