Monday, April 26, 2010

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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Wednesday, April 21, 2010

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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Thursday, April 15, 2010

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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