A/C Diagnosis
CONDITION POSSIBLE CAUSE CORRECTION
RAPID COMPRESSOR
CLUTCH CYCLING (TEN
OR MORE CYCLES PER
MINUTE).
1. Low refrigerant system
charge.
2. Faulty electronic
cycling clutch switch.
3. Faulty Powertrain
Control Module (PCM).
1. See Refrigerant System Leaks in the Diagnosis and
Testing section of this group. Test the refrigerant system
for leaks. Repair, evacuate and charge the refrigerant
system, if required.
2. See Electronic Cycling Clutch Switch in the Diagnosis
and Testing section of this group. Test the electronic
cycling clutch switch and replace, if required.
3. Refer to the proper Diagnostic Procedures manual for
testing of the PCM. Test the PCM and replace, if
required.
EQUAL PRESSURES,
BUT THE
COMPRESSOR CLUTCH
DOES NOT ENGAGE.
1. No refrigerant in the
refrigerant system.
2. Faulty fuse.
3. Faulty compressor
clutch coil.
4. Faulty compressor
clutch relay.
5. Faulty electronic
cycling clutch switch.
6. Faulty low pressure
cut-off switch.
7. Faulty high pressure
cut-off switch.
8. Faulty Powertrain
Control Module (PCM).
9. Faulty heater-A/C
control.
1. See Refrigerant System Leaks in the Diagnosis and
Testing section of this group. Test the refrigerant system
for leaks. Repair, evacuate and charge the refrigerant
system, if required.
2. Check the fuses in the Power Distribution Center and
the junction block. Repair the shorted circuit or
component and replace the fuses, if required.
3. See Compressor Clutch Coil in the Diagnosis and
Testing section of this group. Test the compressor clutch
coil and replace, if required.
4. See Compressor Clutch Relay in the Diagnosis and
Testing section of this group. Test the compressor clutch
relay and relay circuits. Repair the circuits or replace the
relay, if required.
5. See Electronic Cycling Clutch Switch in the Diagnosis
and Testing section of this group. Test the electronic
cycling clutch switch and replace, if required.
6. See Low Pressure Cut-Off Switch in the Diagnosis and
Testing section of this group. Test the low pressure cut-off
switch and replace, if required.
7. See High Pressure Cut-Off Switch in the Diagnosis and
Testing section of this group. Test the high pressure
cut-off switch and replace, if required.
8. Refer to the proper Diagnostic Procedures manual for
testing of the PCM. Test the PCM and replace, if
required.
9. See Heater-A/C Control in the Diagnosis and Testing
section of this group. Test the heater-A/C control and
replace, if required.
NORMAL PRESSURES,
BUT A/C
PERFORMANCE TEST
AIR TEMPERATURES
ARE TOO HIGH.
1. Excessive refrigerant
oil in system.
2. Temperature control
cable improperly installed
or faulty.
3. Blend-air door
inoperative, obstructed or
sealing improperly.
1. See Refrigerant Oil Level in the Service Procedures
section of this group. Recover the refrigerant from the
refrigerant system and inspect the refrigerant oil content.
Restore the refrigerant oil to the proper level, if required.
2. See Temperature Control Cable in the Removal and
Installation and Adjustments sections of this group.
Inspect the temperature control cable for proper routing,
operation and adjustment. Repair as required.
3. See Heater-A/C Housing Door in the Removal and
Installation section of this group. Inspect the blend-air
door for proper operation and sealing and correct, if
required.
DN HEATING AND AIR CONDITIONING 24 - 13
DIAGNOSIS AND TESTING (Continued)
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