Hummer H2. Manual — part 1966

AIR CONDITIONING (A/C) DIAGNOSTICS - PRESSURE ZONE D

Air Conditioning (A/C) Diagnostics - Pressure Zone D

3

z

Restricted air flow

z

Damaged condenser cooling fins

z

Inspect for missing or misaligned air baffles.

Do the following conditions exist?

Go to

Step 4

Go to Step 6

4

Repair the air flow restriction.
Is the repair complete?

Go to

Step 9

-

5

Repair the cooling fan operation fault. Refer to Fan Clutch
Diagnosis in Engine Cooling.
Is the repair complete?

Go to

Step 9

-

6

Feel the liquid line on both sides of the expansion device.Is
the temperature the same before and after the expansion
device?

CAUTION:

Refer to Moving Parts and Hot Surfaces Caution in
Cautions and Notices.

Go to

Step 7

Go to Step 8

7

Replace the damaged/faulty orifice tube. Refer to
Expansion (Orifice) Tube Replacement .
Is the repair complete?

Go to

Step 9

-

8

Air is in the refrigerant system, or the system is
overcharged. Refer to the view screen on the J 43600 for
foreign gas content in the refrigerant. See Special Tools
and Equipment .
Recover and recharge the A/C system. Refer to
Refrigerant Recovery and Recharging .
Is the repair complete?

Go to

Step 9

-

9

1. Record the low and high side pressures and the

instrument panel (I/P) outlet air temperature after
repairs are performed.

2. Compare the pressures and outlet temperature to

those listed in the A/C Performance Chart. Refer to
Air Conditioning (A/C) System Performance
Test .

Are the readings within the specified ranges?

Go to

Step 10

Go to Air Conditioning

(A/C) System Performance

Test

10

Operate the system in order to verify the repair.
Did you find and correct the condition?

System

OK

Symptoms - HVAC

Systems - Automatic in

HVAC Systems - Automatic

2004 Hummer H2

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

Step

Action

Yes

No

DEFINITION: The low side pressure is lower than normal and the high side pressure is higher than
normal.

z

A restriction in the A/C system.

z

Debris in the A/C system.

1

Were you sent here from the A/C System Performance
Test?

Go to

Step 2

Go to Air Conditioning

(A/C) System Performance

Test

2

Feel the liquid line before the expansion device.Is the
liquid line cold before the expansion device?

CAUTION:

Refer to Moving Parts and Hot Surfaces Caution in
Cautions and Notices.

Go to

Step 3

Go to Step 8

3

Feel along the surfaces of the following high side
components:

z

The compressor discharge hose

z

The condenser

z

The liquid line between the condenser and the
expansion device

Did you detect an abrupt drop in temperature along the
surfaces of any of the listed components?

Go to

Step 7

Go to Step 4

4

1. Feel the liquid line at the expansion device location

for extreme cold, possibly accompanied by heavy
frost.

2. Feel along the liquid line beyond the expansion

device location for warm temperature.

Is the liquid line extremely cold at the expansion device
location and warm beyond the expansion device location?

Go to

Step 11

Go to Step 5

5

Feel along the surfaces of the following low side
components:

z

The evaporator inlet tube between the expansion
device and the evaporator core

z

The evaporator outlet tube between the evaporator
core and the compressor

z

The accumulator

z

The compressor suction hose

2004 Hummer H2

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

Did you feel an abrupt temperature change along the
surfaces of any of the listed components?

Go to

Step 7

Go to Step 6

6

Feel along the surfaces of the low and the high side
components:

z

The evaporator inlet tube between the expansion
device and the evaporator core

z

The evaporator outlet tube between the evaporator
core and the accumulator

z

The accumulator

z

The compressor suction hose

z

The compressor discharge hose

z

The condenser

z

The evaporator inlet tube between the condenser
and the expansion device

Are the temperatures of these components only mildly
warm?

Go to

Step 14

Go to Step 8

7

1. Recover the refrigerant. Refer to Refrigerant

Recovery and Recharging .

2. Remove the restriction from the component, or

replace the component which produced an abrupt
temperature drop.

Is the repair complete?

Go to

Step 9

-

8

1. Recover the refrigerant and evacuate the system.

Refer to Refrigerant Recovery and Recharging .

2. Record the weight of the recovered refrigerant.

3. Compare the weight of the recovered refrigerant

with the system capacity. Refer to Refrigerant
System Capacities .

Is the weight of the recovered refrigerant charge greater
than 75% of the total system capacity?

Go to

Step 9

Go to Step 10

9

Recharge the A/C system. Refer to Refrigerant
Recovery and Recharging .
Is the cooling performance improved?

Go to

Step 21

Go to Step 10

10

1. Leak test the system. Refer to Leak Testing .

2. Repair any leaks.

Go to

2004 Hummer H2

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

Is the repair complete?

Step 21

-

11

The expansion device is restricted.
Replace the expansion device. Refer to Expansion
(Orifice) Tube Replacement .
Are metal flakes present?

Go to

Step 12

Go to Step 13

12

1. Remove the suction line from the vehicle. Refer to

Suction Hose Replacement .

2. Inspect the hose for debris by blowing shop air

through one end of the hose while covering the
other end with a shop towel.

3. Observe the amount of debris collected in the shop

towel.

Did a large amount of debris collect in the shop towel?

Go to

Step 18

Go to Step 20

13

If the expansion device was restricted with a brown or
black residue, perform the following procedure:

1. Flush the A/C system. Refer to Flushing .

2. Replace the accumulator. Refer to Accumulator

Replacement .

Are the repairs complete?

Go to

Step 21

-

14

1. Recover the refrigerant. Refer to Refrigerant

Recovery and Recharging .

2. Disconnect the suction and the discharge lines from

the compressor. Refer to Suction Hose
Replacement and to Discharge Hose
Replacement .

3. Inspect for the presence of debris in the compressor

suction port.

Is debris present in the compressor suction port?

Go to

Step 15

Go to Step 19

15

1. Remove the debris from the suction port.

2. Inspect the expansion device for damage or debris.

Refer to Expansion (Orifice) Tube Replacement .

Did you find evidence of damage or debris?

Go to

Step 17

Go to Step 16

If the expansion device does not show any signs of
damage or debris, perform the following procedure:

1. Remove the suction line from the vehicle. Refer to

Suction Hose Replacement .

2004 Hummer H2

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2