Hummer H1 (2006+). Manual - part 320
11-14 Heating/Ventilation/Air Conditioning (HVAC)
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Low Side and High Side
Normal But Cooling is
Inadequate
1.
Air and/or moisture in the system.
1.
Leak test the system. Repair leaks if neces-
sary. If leaks are not evident, evacuate and
recharge the system.
2.
Receiver/Dryer fault.
2.
Evacuate the system, replace the receiver/
dryer and recharge the system.
Compressor Diagnosis
Condition
Possible Cause
Correction
Compressor Noise
1.
System overcharge.
1.
Recover all R-134a with J–39500-A ser-
vice cart and recharge with the proper
charge.
2.
Drive belt problem.
2.
Replace the belt if worn, frayed, cut or
torn.
3.
Compressor clutch fault.
3.
Replace the core or pulley bearing as
needed.
4.
Compressor internal fault.
4.
Replace the compressor if pressure test
indicates worn, inoperative condition.
Compressor Does Not
Engage
1.
System fuse blown.
1.
Replace the fuse. Check the circuit for
shorts, ground.
2.
Clutch wires damaged.
2.
Repair the wires.
3.
Pressure cycling clutch or A/C cutout
switch fault.
3.
Replace the switch(s) as needed.
4.
Compressor clutch failure.
4.
Replace the clutch core and/or pulley as
needed.
5.
Compressor seized.
5.
Replace compressor.
6.
High engine coolant temperature trigger-
ing A/C cutout switch.
6.
Let the engine cool down and fix the
engine cooling system problem first.
Compressor Engages but
Cooling is Inadequate
1.
A/C duct restrictions, loose connections.
1.
Repair as needed.
2.
System leaks (high side pressure below
50 psi (345 kPa)).
2.
Check for leaks with J-41995 leak
detection tool and repair as needed.
3.
Expansion valve inoperative.
3.
Replace the valve.
4.
Receiver/Dryer fault.
4.
Replace the receiver/dryer
5.
Condenser fault.
5.
Replace the condenser.
6.
Compressor
internal
wear.
6.
Replace the compressor if pressure
indicates internal wear or damage.
A/C Pressure Test Diagnosis (Continued)
Condition
Possible Cause
Correction