Hummer H1 Service Manual page 731

11-12 Heating/Ventilation/Air Conditioning (HVAC)
Condition
Compressor Noise
Compressor Does Not Engage
Compressor Engages but Cool-
ing is Inadequate
Compressor Diagnosis
Possible Cause
1. System overcharge.
2. Drivebelt problem.
3. Compressor clutch fault.
4. Compressor internal fault.
1. System fuse blown.
2. Clutch wires damaged.
3. Pressure cycling clutch, or A/C cutout
switch fault.
4. Compressor clutch failure.
5. Compressor seized.
6. High engine coolant temperature trig-
gering A/C cutout switch.
1. A/C duct restrictions, loose connec-
tions.
2. System leaks (high side pressure
below 50 psi (345 kPa)).
3. Expansion valve inoperative.
4. Receiver/Dryer fault.
5. Condenser fault.
6. Compressor internal wear.
______________________
Correction
1. Recover all R-134a with J–39500-A ser-
vice cart and recharge with proper charge.
2. Replace belt if worn, frayed, cut or torn.
3. Replace core or pulley bearing as needed.
4. Replace compressor if pressure test
indicates worn, inoperative condition.
1. Replace fuse. Check circuit for shorts,
ground.
2. Repair wires.
3. Replace switch(s) as needed.
4. Replace clutch core and/or pulley as
needed.
5. Replace compressor.
6. Let engine cool down and fix engine
cooling system problem first.
1. Repair as needed.
2. Check for leaks with D-Tek tool and
repair as needed.
3. Replace valve.
4. Replace
5. Replace condenser.
6. Replace compressor if pressure indicates
internal wear or damage.
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