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.
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.
