Hummer H2. Manual - part 1968

NOISE DIAGNOSIS - BLOWER MOTOR 

Noise Diagnosis - Blower Motor 

11

Repair the heating concern. Refer to Heating 
Performance Diagnostic . 
Is the repair complete?

Go to 

Step 14

-

12

Repair the A/C performance concern. Refer to Air 
Conditioning (A/C) System Performance Test . 
Is the repair complete?

Go to 

Step 14

-

13

Repair the recirculation door concern. Refer to Air 
Recirculation Malfunction in HVAC Systems - 
Automatic. 
Is the repair complete?

Go to 

Step 14

-

14

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

System 

OK

Go to Step 2

Step

Action

Yes

No

DEFINITION: Noise originating from the blower motor.

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

Inspect the air inlet grille for debris. 
Is debris present?

Go to 

Step 8

Go to Step 3

3

1. Sit inside the vehicle.  

2. Close the vehicle doors and windows.  

3. Turn ON the ignition, with the engine OFF.  

4. Cycle the blower motor through all of the 

speeds and modes in order to determine where 
and when the noise occurs.  

Is a noise evident during the blower operation?

Go to 

Step 4

Go to Step 12

4

Inspect for excessive vibration at each blower motor 
speed by feeling the blower case. 
Is excess vibration present?

Go to 

Step 6

Go to Step 5

5

Listen to the blower motor at each speed. 
Is the blower motor making a squeaking or chirping 
noise?

Go to 

Step 9

Go to Step 12

6

1. Remove the blower motor. Refer to Blower 

Motor Replacement .  

2. Inspect the blower motor impeller for deposits 

of foreign material.  

3. Inspect the blower motor for deposits of foreign 

material.  

 

2004 Hummer H2 

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

  

NOISE DIAGNOSIS - AIR CONDITIONING (A/C) SYSTEM 

Noise Diagnosis - Air Conditioning (A/C) System 

Did you find any foreign material on the blower 
motor or blower motor impeller?

Go to 

Step 8

Go to Step 7

7

Inspect the blower motor for the following conditions: 

z

Cracked blades  

z

A loose impeller retainer  

z

Improper impeller alignment  

 
Did you find any of these conditions?

Go to 

Step 11

Go to Step 10

8

Remove the foreign material. 
Is the action complete?

Go to 

Step 10

-

9

Replace the blower motor. Refer to Blower Motor 
Replacement . 
Is the repair complete?

Go to 

Step 12

-

10

Install the blower motor. Refer to Blower Motor 
Replacement . 
Is the action complete?

Go to 

Step 12

-

11

Replace the blower motor impeller. Refer to Blower 
Motor Impeller Replacement . 
Is the action complete?

Go to 

Step 12

-

12

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

System 

OK

Go to Step 2

Step

Action

Yes

No

DEFINITION: Noise originating from the A/C compressor, drive belt, or the A/C lines.

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. A/C system noises can be generally categorized into 3 

areas: 

z

Screeching, squealing, chirping noises  

z

Moaning noises  

z

Vibration/rattle noises  

2. Start the engine.  

3. Ensure that the A/C is ON.  

Is a screeching, squealing noise heard when the A/C is 
engaged?

Go to 

Step 3

Go to Step 9

 

2004 Hummer H2 

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

  

3

With the engine OFF, inspect the drive belt for excessive 
wear. Refer to Drive Belt Excessive Wear Diagnosis in 
Engine Mechanical - 6.0L. 
Is the drive belt excessively worn?

Go to 

Step 18

Go to Step 4

4

Inspect the drive belt tension. Refer to Drive Belt Tensioner 
Diagnosis in Engine Mechanical - 6.0L. 
Is the drive belt tension correct?

Go to 

Step 5

Go to Step 19

5

Inspect the drive belt for excessive oil coverage. 
Is the drive belt covered with oil?

Go to 

Step 17

Go to Step 6

6

1. Start the engine.  

2. Ensure that the A/C is ON.  

3. Inspect the compressor and the clutch.  

Is the A/C compressor locked up?

Go to 

Step 24

Go to Step 7

7

Is the A/C compressor clutch slipping?

Go to 

Step 23

Go to Step 8

8

Using a stethoscope, listen to the A/C compressor for any 
abnormal noises.Is the compressor causing an abnormal noise?

CAUTION:

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

Go to 

Step 15

Go to Step 10

9

Does a moaning noise exist when the A/C clutch is engaged?

Go to 

Step 10

Go to Step 12

10

Listen to the A/C compressor components and mounting for 
noise concerns using a stethoscope. 
Are any of these components loose, damaged or excessively 
worn?

Go to 

Step 20

Go to Step 11

11

1. Idle the engine.  

2. Engage the A/C compressor clutch.  

3. Using a stethoscope, move around the entire refrigerant 

plumbing system. Listening for any abnormal noises 
caused by a component of the A/C system touching 
another component.  

Are any of the A/C components grounding out and causing a 
vibration noise?

Go to 

Step 22

Go to Step 13

12

Does a vibration or rattle noise exist when the A/C clutch is 
engaged?

Go to 

Step 13

Go to Step 14

13

Does the noise stop when the A/C clutch is disengaged?

Go to 

Step 15

Go to Step 25

1. Idle the engine in PARK with the A/C compressor 

clutch engaged.  

 

2004 Hummer H2 

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

  

NOISE DIAGNOSIS - HVAC MODULE 

Noise Diagnosis - HVAC Module 

14

2. Using a stethoscope, move around the entire A/C 

system testing for any abnormal noises caused by a 
component.  

Do any of the A/C components cause an abnormal noise?

Go to 

Step 21

Go to Step 25

15

Verify that the A/C system is properly charged. Refer to 
Refrigerant System Capacities . 
Is the A/C system properly charged?

Go to 

Step 26

Go to Step 16

16

Recharge the A/C system to specification. Refer to 
Refrigerant Recovery and Recharging . 
Is the abnormal compressor noise still present?

Go to 

Step 24

Go to Step 26

17

Repair the oil leak. Refer to Oil Leak Diagnosis in Engine 
Mechanical - 6.0L. 
Is the repair complete?

Go to 

Step 26

-

18

Replace the A/C drive belt. Refer to Drive Belt Replacement 
- Air Conditioning in Engine Mechanical - 6.0L. 
Is the repair complete?

Go to 

Step 26

-

19

Replace the A/C drive belt tensioner. Refer to Drive Belt 
Tensioner Replacement - Air Conditioning in Engine 
Mechanical - 6.0L. 
Is the repair complete?

Go to 

Step 26

-

20

Repair or replace the A/C compressor mounting component. 
Is the repair complete?

Go to 

Step 26

-

21

Repair or replace the component which is causing the 
moaning concern as needed. 
Is the repair complete?

Go to 

Step 26

-

22

Correctly route or insulate the A/C component. 
Is the repair complete?

Go to 

Step 26

-

23

Replace the A/C compressor clutch. Refer to Compressor 
Clutch Plate/Hub Assembly Replacement . 
Is the repair complete?

Go to 

Step 26

-

24

Replace the A/C compressor. Refer to Compressor 
Replacement . 
Is the repair complete?

Go to 

Step 26

-

25

The concern may be caused by an engine related component. 
Refer to Vibration Analysis - Engine in Vibration Diagnosis 
and Correction. 
Did you find and correct the condition?

Go to 

Step 26

-

26

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