Hummer H1 (2002+). Manual - part 182

 

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 Heating/Ventilation/Air Conditioning (HVAC)  11-7

  

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05745159

 

Checking/Adding Refrigerant Oil

 

It is not necessary to check or add oil as routine maintenance. It
is necessary to add oil when the evaporator, condenser, com-
pressor, or receiver/dryer has been replaced, or there was a
large leak. When a system is discharged, it is also necessary to
replace any oil carried out with the refrigerant.

 

CAUTION: 

 

All replacement compressors are shipped with 8

oz. (237 ml) of oil in the crankcase. This oil must be drained
completely, and replaced in like amount to the failed compres-
sor. Add 2 oz above what is found in the failed compressor.
Failure to do so will cause an overcharge of oil in the system
and will lower cooling efficiency. An extreme overcharge con-
dition may cause early compressor failure.

 

1.

If a major component was replaced, add clean GM PAG  
oil as follows.

a.

Condenser – 1 oz. (30 ml).

b.

Evaporator – 3 oz. (84 ml).

c.

Receiver/Dryer – 2 oz. (60 ml).

d.

Auxiliary Unit - 2 oz. (60 ml).

e.

Compressor – see step 3.

f.

Any other known quantity of oil.

2.

Add oil to the system. Add directly into component. Oil
can also be added directly from the service cart after
system evacuation.

3.

Check oil in compressor:

a.

Recover/discharge A/C system refrigerant.

b.

Remove compressor.

c.

Tip compressor on hose connection end and drain into
a clean container. Allow to drain for ten minutes.
Measure and discard oil.

d.

When the new compressor is recieved, drain the oil
that was shipped inside. Replace the oil in an equal
amout to that which was drained from the old
compressor. If less than one ounce (30 ml) is drained
from the old compressor, add two ounces (60 ml) to
the new compressor. If more than one ounce (30 ml)
is drained, replace the same amount in the new one.

e.

Plug or block ports and turn compressor over slowly
several times.

4.

Perform evacuation, recharging, and leak testing of
system.

 

Charging The A/C System

 

NOTE: 

 

If A/C system requires replacement of a major compo-

nent, refrigerant oil must be added to system to compensate for
loss.

1.

Evacuate A/C system. Follow manufacturer’s recom-
mended service procedures for the equipment being used.

2.

Connect refrigerant source to center hose if manifold
gauge set J–39183-C is being used.

3.

Open refrigerant R-134a source to allow refrigerant to
flow into system.

4.

Purge center hose, low-pressure hose, and high-pressure
hose as follows:

a.

Slightly loosen center hose at manifold gauge set
center port until refrigerant escapes, then tighten hose.

b.

Open high-pressure and low-pressure gauge valves to
allow refrigerant to flow into high-pressure and low-
pressure hoses.

c.

Turn high-pressure and low-pressure gauge valves
clockwise to OFF position.

d.

Purge high-pressure and low-pressure hoses at service
ports of compressor.

 

WARNING:  Make sure high-pressure gauge valve is in
closed position on manifold gauge set during charging.
Failure to do so will cause compressor to build pressure in
refrigerant container. This could result in injury to per-
sonnel or damage to equipment if the container cracks.

 

5.

Start engine and set engine speed at 1500 rpm.

6.

Turn A/C system to max cold and blower fan on high
speed.

 

NOTE: 

 

Keep refrigerant container upright at all times so re-

frigerant enters system as a gas.

7.

Open low-pressure gauge valve until system is fully
charged.

8.

Close low-pressure gauge valve.

 

11-8

Heating/Ventilation/Air Conditioning (HVAC)

 

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SYSTEM DIAGNOSIS

 

System diagnosis should begin with the system performance
checks described in this section. The checks will help verify
that a problem actually exists as opposed to an incorrect setting
by the vehicle operator.

In addition to the performance checks, problem verification
will also involve pressure testing, leak testing, individual com-
ponent testing, air flow and temperature testing, and refrigerant
recovery, evacuation, or recharge. The tools and equipment re-
quired for this purpose are described in each procedure.

The diagnosis charts outline common heater and A/C prob-
lems. The potential causes are listed in order of probability
(most-to-least probable). However, the charts are guides only
and will not outline all of the possible system faults that might
occur. System testing is still required for verification.

The primary diagnostic method of checking A/C system per-
formance is the pressure test. The test is performed with mani-
fold gauge set J–39183-C. The gauges   allow suction and
discharge pressures to be checked while the system is operat-
ing. The pressure test diagnosis charts describe common faults
that cause incorrect system pressures.

 

 Water Valve Does Not Operate

 

Step Action

Value(s)

Yes

No

 

1

Actuate the water valve lever by hand, does it 
move freely, and does spring pressure re-open the 
valve when you release it.?

go to step 3

go to step 2

2

Loosen the clamp securing the water valve to the 
body. Does the valve move freely now?

Problem is cor-

rected

Replace the water 

valve

3

Using a hand vacuum pump J–35555, apply 
18”Hg to the water valve vacuum motor. Does the 
valve close and hold vacuum for at least 1 minute.

18”Hg

go to step 4

Replace water 

valve

4

Release the vacuum on the water valve, does the 
valve return to the open position?

go to step 5

Replace the water 

valve

5

Attach J–35555 to the vacuum supply line for the 
water valve. Start and idle the engine. Rotate the 
temperature control dial to the cold position. Is 
sufficient vacuum present?

18”Hg

go to step 6

go to step7

6

 With J–35555 still attached to water valve vac-
uum supply line, rotate temperature control dial to 
the hot position. Does atmosphere vent in?

0” Hg

System is working 

correctly

go to step 8

7

Check for kinks, breaks and blockages in the vac-
uum harness between the water valve and the 
HVAC control head. Are any found?

Repair or replace 

vacuum harness as 

necessary

go to step 9

8

With J–35555 still attached to water valve vac-
uum supply line, disconnect HVAC control head 2 
hose blk/wht connector. Does atmosphere vent 
in?

0”Hg

Replace the con-

trol head

Remove blockage 

in white vacuum 

line to water 

valve

9

Disconnect 2 hose blk/wht connector at HVAC 
control head. Install J–35555 onto blk hose. Start 
and Idle engine. Is sufficient vacuum present?

18”Hg

Replace the con-

trol head

go to step 10

10

Locate vacuum connection on rear of vacuum 
pump. Install J–35555 onto connection and start 
and idle engine. Is sufficient vacuum present?

18”Hg

Locate and repair 

blockage/breakage 

in vacuum harness 

between vacuum 

pump and HVAC 

control head

Replace vacuum 

pump

 

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 Heating/Ventilation/Air Conditioning (HVAC)  11-9

  

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05745159

 

Heater Diagnosis

 

Condition

Possible Cause

Correction

 

Inadequate or No Heat

1.

Heat control knob not set in heat mode, or 
engine not warmed up.

1.

Advise owner/driver.

2.

Low engine coolant level.

2.

Add coolant as needed and check for leaks.

3.

Air in coolant system. Usually occurs after 
coolant drain and refill.

3.

Bleed air from cooling system.

4.

Thermostat faulty.

4.

Replace thermostat(s) if stuck closed or
remains open continuously.

5.

Kinked or collapsed radiator hose or heater 
hose.

5.

Replace hose.

6.

Water pump failure.

6.

Replace pump.

7.

Heater core plugged or leaking.

8.

Replace core.

9.

Blower motor fault.

10. Check circuit fuse and wiring. Replace 

motor if foiled.

11. Outside air leaking into heater core section 

of plenum.

12. Seal plenum or realign as needed.

13. Water control valve or vacuum solenoid 

fault.

14. Replace valve if stuck closed or partially 

open. Replace solenoid if closed or 
shorted.

15. Blend air door stuck or misadjusted.

16. Replace main unit.

Inadequate Defrost

1.

Duct restricted or connecting hose is loose.

1.

Repair as needed.

2.

Defroster nozzle misaligned or damaged 
(bent, cracked, partially closed).

2.

Repair as needed.

3.

Insufficient heat.

3.

Check for low coolant level, coolant leaks,
air in system, faulty thermostat or water
valve, collapsed hose, plugged heater core,
binding air door in main unit.

4.

Blower motor fault.

4.

Check circuit fuse and wiring. Replace
motor if open or shorted.

 

NOTE: 

 

Improperly adjusted or binding mode door linkage can also cause low, poor or no airflow to any location. 

 

11-10

Heating/Ventilation/Air Conditioning (HVAC)

 

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Air Flow Diagnosis

 

Condition

Possible Cause

Correction

 

No Air Flow from Outlets

1.

Blower motor fuse blown.

1.

Replace fuse.

2.

Blower motor harness damage (short, 
open, loose connection).

2.

Check harness continuity with ohmmeter
and repair as needed.

3.

Blower motor fault.

3.

Run 12V jumper directly to motor. Motor
should run at high speed. If motor fails to
run, replace it. If motor runs, check
resistor.

4.

Blower 

motor 

resistor 

fault.

4.

Replace resistor if motor runs when
resistor is bypassed or if blower runs at
high speed setting but will not run at one
or all of the lower settings.

Air Flows from Incorrect 
Outlets

1.

Actuator motor or linkage fault.

1.

Remove passenger side trim to expose 
both actuator motors and observe linkage 
operation. Adjust linkage if required. 
Replace either motor and/or linkage if 
inoperative.

Low-Weak Air Flow from 
Outlets

1.

Restriction in air ducts.

1.

 Repair as needed.

2.

Restriction in intake hose into main unit.

2.

 Repair as needed.

3.

Blower 

motor 

fault.

3.

Replace motor or resistor if either is
inoperative.

4.

Misadjusted or binding mode door linkage. 

4.

 Adjust as necessary. 

 

 A/C System Diagnosis

 

Condition

Possible Cause

Correction

 

Water on Passenger Side 
Floor

1.

Evaporator drain hose plugged or installed 
incorrectly.

1.

Open hose with utility knife or tirm end off 
hose. Make sure routing of hose is to out-
side of passenger compartment.

2.

Coolant leak from heater core.

2.

Replace core if leaking. Replace clamps or
hoses if leaking at heater core connections.

3.

Road splash entering compartment through 
evaporator/heater core opening, or through 
intake air inlet area.

3.

Water test and seal off as needed.

4.

Water leaking into passenger compartment.

4.

Water test and correct leaks.

Musty Smell

1.

Water leaking into passenger compartment.

1.

Water test and correct leaks.

2.

Evaporator drain partially or fully plugged.

2.

Open or tirm off drain hose with utility
knife. Correct routing if necessary.

3.

Mold-Mildew development on evaporator 
surface, coils, fins.

3.

Clean evaporator with mild disinfectant
soap or replace evaporator as necessary.