Hummer H2. Manual - part 1969

Step

Action

Yes

No

DEFINITION: Noise originating from the HVAC module.

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. Cycle through all of the following: 

z

Blower motor speeds  

z

HVAC modes  

z

Temperature control settings  

3. Determine the type of noise: 

z

Scrape, pop  

z

Tick/click, chirp, or groaning  

z

Air rush/whistle  

Is a scrape or pop noise evident when selecting modes or 
temperature settings?

Go to 

Step 6

Go to Step 3

3

Is a tick/click, chirping, groaning, or scraping noise 
present, but decreases as blower motor speed is 
decreased?

Go to 

Step 6

Go to Step 4

4

Is an air rush/whistle noise evident in all modes, but not 
all temperature settings?

Go to 

Step 6

Go to Step 5

5

Is an air rush/whistle noise evident only in defrost or 
floor mode?

Go to 

Step 6

Go to Step 6

6

Remove the instrument panel (I/P) carrier. Refer to 
Instrument Panel (I/P) Carrier Replacement in 
Instrument Panel, Gauges, and Console. 
Is the action complete?

Go to 

Step 7

-

7

z

Inspect the air flow doors for proper operation.  

z

Inspect the ducts for obstructions or foreign 
materials.  

Were any of these conditions found?

Go to 

Step 10

Go to Step 8

8

Inspect the mode and temperature doors and seals for 
warping or cracking. 
Are the doors in normal condition?

Go to 

Step 11

Go to Step 9

9

Replace the appropriate door and/or seals. 
Is the repair complete?

Go to 

Step 11

-

10

Remove any obstructions or foreign material found. 
Is the action complete?

Go to 

Step 11

-

11

Install the I/P carrier. Refer to Instrument Panel (I/P) 
Carrier Replacement in Instrument Panel, Gauges, and 

 

2004 Hummer H2 

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

  

ODOR DIAGNOSIS 

Odor Diagnosis 

Console. 
Is the action complete?

Go to 

Step 12

-

12

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

System 

OK

Go to Step 2

Step

Action

Yes

No

DEFINITION: Odor originating or noticed through the HVAC system.

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. Sit inside the vehicle.  

2. Close all of the doors and windows.  

3. Start the engine.  

4. Allow the engine to idle at normal operating 

temperature.  

5. Select the maximum blower speed.  

6. Select the PANEL air outlet mode.  

7. Select the coldest temperature setting.  

8. Cycle through all of the blower speeds, modes, and 

temperatures to define what type of odor is present. 

z

Musty smell  

z

Coolant smell  

z

Oil smell  

Does the odor have a musty smell?

Go to 

Step 3

Go to Step 8

3

Inspect the HVAC grille for debris. 
Is debris present?

Go to 

Step 4

Go to Step 5

4

Remove any debris. 
Is the action complete?

Go to 

Step 15

-

5

Inspect for wet carpeting. 
Is the carpet wet?

Go to 

Step 6

Go to Step 14

6

Inspect for the following conditions: 

z

Water leaks around the windshield  

z

Blockage of the HVAC module drain  

z

Leaks around the door seals  

 
Is a leak present?

Go to 

Step 7

Go to Step 14

 

2004 Hummer H2 

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

  

REPAIR INSTRUCTIONS 

ODOR CORRECTION 

Eliminating Air Conditioning Odor 

Odors may be emitted from the air conditioning system primarily at start up in hot, humid climates. The 
following conditions may cause the odor: 

z

Debris is present in the HVAC module.  

z

Microbial growth on the evaporator core 

7

Repair the leak as necessary. 
Is the repair complete?

Go to 

Step 15

-

8

Does the odor have a coolant smell?

Go to 

Step 9

Go to Step 12

9

Inspect the cooling system for leaks. Refer to Loss of 
Coolant in Engine Cooling. 
Is a leak present?

Go to 

Step 10

Go to Step 12

10

Inspect for coolant leaking inside the vehicle or for a film 
build-up on the windshield. 
Is the condition present?

Go to 

Step 11

Go to Step 15

11

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

Go to 

Step 15

-

12

Does the odor have an oily smell?

Go to 

Step 13

Go to Step 15

13

1. Inspect the engine compartment for any leaks. Refer 

to the following procedures: 

z

Oil Leak Diagnosis in Engine Mechanical - 
6.0L  

z

Fluid Leak Diagnosis in Automatic 
Transmission - 4L60-E  

z

Power Steering Fluid Leaks in Power 
Steering System  

2. Repair any oil leaks.  

Is the repair complete?

Go to 

Step 15

-

14

A musty odor can be caused by mold or mildew build-up 
on the evaporator or the heater core or inside of the HVAC 
module. Refer to Odor Correction . 
Is the action complete?

Go to 

Step 15

-

15

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

  

When the blower motor fan is turned on, the microbial growth may release an unpleasant musty odor into the 
passenger compartment. To remove odors of this type, the microbial growth must be eliminated. Perform the 
following procedure: 

Deodorize the evaporator core using Deodorizing Aerosol Kit. 

Perform the following steps in order to deodorize the A/C system: 

1. Ensure that the plenum which draws outside air into the HVAC module is clear of debris.  

2. Disable the A/C compressor clutch operation by disconnecting the clutch coil electrical connector.  

3. Dry the evaporator core by performing the following steps: 

1. Start the engine.  

2. Select the warmest temperature setting.  

3. Select the recirculation mode.  

4. Run the blower motor on high for 10 minutes.  

4. Locate an area in the air conditioning duct between the blower motor and the evaporator core downstream 

of the blower motor.  

5. Drill a 3.175 mm (0.125 in) hole where the hole will not interfere with or damage the following 

components: 

z

The blower motor  

z

The evaporator core  

z

Any other operating part the of system  

6. Wear safety goggles and latex gloves in order to perform the following actions: 

1. Select the maximum blower speed.  

2. Insert the deodorizer extension tube into the hole to the mark on the extension tube.  

3. Use short spray bursts and vary the direction of spray for a 2-3 minute period of time.  

7. Shut the engine OFF. Allow the vehicle to sit for 3-5 minutes.  

8. Seal the 3.175 mm (0.125 in) hole with body sealer or RTV gasket compound.  

9. Start the engine.  

10. Operate the blower motor on high for 15-20 minutes to dry.  

11. Reconnect the A/C compressor clutch coil electrical connector.  

12. Verify proper clutch operation.  

REFRIGERANT RECOVERY AND RECHARGING 

Tools Required 

z

J 43600 ACR 2000 Air Conditioning Service Center. See Special Tools and Equipment .  

z

J 45037 A/C Oil Injector. See Special Tools and Equipment .  

CAUTION: Avoid breathing the A/C Refrigerant 134a (R-134a) and the lubricant vapor 

 

2004 Hummer H2 

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2