Hummer H2. Manual — part 1967

16

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 19

17

1. Replace the expansion device. Refer to Expansion

(Orifice) Tube Replacement .

2. If the expansion device was restricted, observe the

type of debris present.

Are metal flakes present?

Go to

Step 12

Go to Step 13

18

If a large amount of debris was collected in the shop towel
from the compressor hose assembly, perform the
following procedure:

1. Replace the accumulator. Refer to Accumulator

Replacement .

2. Install an A/C refrigerant filter. Refer to Air

Conditioning (A/C) Refrigerant Filter
Installation .

Is the repair complete?

Go to

Step 19

-

19

Install the suction and the discharge lines. Refer to
Suction Hose Replacement and to Discharge Hose
Replacement .
Are the repairs complete?

Go to

Step 21

-

20

1. Install the suction and the discharge lines. Refer to

Suction Hose Replacement and to Discharge
Hose Replacement .

2. Install an A/C refrigerant filter. Refer to Air

Conditioning (A/C) Refrigerant Filter
Installation .

3. Recharge the A/C system. Refer to Refrigerant

Recovery and Recharging .

Are the repairs complete?

Go to

Step 21

-

1. Record the low and the high side pressures and the

panel outlet air temperature after you perform the
repairs.

2004 Hummer H2

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

HEATING PERFORMANCE DIAGNOSTIC

Heating Performance Diagnostic

21

2. Compare the pressures and the panel 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 as shown on
the A/C Performance Chart?

Go to

Step 22

Go to Air Conditioning

(A/C) System Performance

Test

22

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

System

OK

Go to Symptoms - HVAC

Systems - Automatic in

HVAC Systems - Automatic

Step

Action

Yes

No

DEFINITION: Heating system performance.

1

Were you sent here from Symptoms or another diagnostic
table?

Go to

Step 2

Go to Too Cold in

Vehicle in HVAC

Systems - Automatic

2

1. Start the engine.

2. Allow the engine to idle.

Does the engine reach a normal operating temperature?

Go to

Step 3

Go to Step 9

3

1. Allow the engine to idle.

2. Select the FLOOR mode.

3. Select the minimum blower speed.

4. Select the warmest temperature setting.

5. Feel the temperature of the inlet and outlet heater hoses

at the heater core.

Does the inlet heater hose feel warmer than the outlet heater
hose?

CAUTION:

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

Go to

Step 7

Go to Step 4

4

1. Install a thermometer into the center IP PANEL air

outlet.

2. Secure a thermometer to the heater core outlet hose.

3. Select the PANEL mode.

4. Select the maximum blower speed.

5. Select the warmest temperature setting.

2004 Hummer H2

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

DEFROSTING INSUFFICIENT

6. Record the temperature at the following locations:

z

The center IP PANEL air outlet

z

The heater core outlet hose

7. Compare the recorded temperatures.

Are the two temperature readings about equal?

Go to

Step 5

Go to Step 6

5

1. Inspect and repair the following areas of the vehicle for

cold air leaks:

z

The cowl

z

The recirculation door

z

The HVAC module case

2. Perform the necessary repairs.

Are the repairs complete?

Go to

Step 10

-

6

1. Inspect the temperature door operation. Refer to

Diagnostic System Check - HVAC Systems -
Automatic in HVAC Systems - Automatic.

2. Perform any necessary repairs.

Are the repairs complete?

Go to

Step 10

-

7

1. Turn OFF the engine.

2. Backflush the heater core.

3. Start the engine.

4. Select the FLOOR mode.

5. Select the minimum blower speed.

6. Select the warmest temperature setting.

7. Feel the temperature of the inlet and outlet heater hoses

at the heater core.

Does the inlet heater hose feel warmer than the outlet heater
hose?

Go to

Step 8

Go to Step 10

8

Replace the heater core. Refer to Heater Core Replacement .
Is the repair complete?

Go to

Step 10

-

9

Repair the low engine temperature concern. Refer to Engine
Fails To Reach Normal Operating Temperature in Engine
Cooling.
Is the repair complete?

Go to

Step 10

-

10

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

System

OK

Go to Step 2

2004 Hummer H2

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

Defrosting Insufficient

Step

Action

Yes

No

DEFINITION: Time required to defrost the windshield is longer than normal.

1

Were you sent here from Symptoms or another
diagnostic table?

Go to

Step 2

Go to Symptoms - HVAC

Systems - Automatic in HVAC

Systems - Automatic

2

1. Start the engine.

2. Select the DEFROST mode.

3. Select the maximum blower speed.

Does sufficient air flow from the defroster outlets?

Go to

Step 3

Go to Step 10

3

Measure the engine operating temperature.
Does engine reach a normal operating temperature?

Go to

Step 10

Go to Step 8

4

1. Select the minimum blower speed.

2. Select the warmest temperature setting.

3. Feel the temperature of the inlet and outlet hoses

at the heater core.

Does the inlet heater hose feel warmer than the outlet
heater hose?

CAUTION:

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

Go to

Step 11

Go to Step 5

5

Test the operation of the A/C compressor clutch.
Does the A/C compressor clutch engage?

Go to

Step 7

Go to Step 6

6

Repair the A/C compressor clutch. Refer to HVAC
Compressor Clutch Does Not Engage in HVAC
Systems - Automatic.
Is the repair complete?

Go to

Step 14

-

7

Perform the A/C system performance test. Refer to
Air Conditioning (A/C) System Performance Test .
Is the A/C system operating within the specifications?

Go to

Step 9

Go to Step 12

8

Repair the low engine temperature concern. Refer to
Engine Fails To Reach Normal Operating
Temperature in Engine Cooling.
Is the repair complete?

Go to

Step 14

-

9

Inspect for correct operation of the recirculation door.
Is the recirculation door operating correctly?

Go to

Step 14

Go to Step 13

10

Repair the air delivery concern. Refer to Air Delivery
Improper in HVAC Systems - Automatic.
Is the repair complete?

Go to

Step 14

-

2004 Hummer H2

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2