Hummer H2. Manual - part 1946

Schematic Reference:HVAC Schematics 
Connector End View Reference: HVAC Connector End Views 
DEFINITION: The A/C compressor clutch will not disengage when an A/C request has not been made 
and a Powertrain DTC has not been set.

1

Did you perform the HVAC Diagnostic System Check?

Go to 

Step 2

Go to Diagnostic System 

Check - HVAC Systems - 

Automatic

2

1. Start the engine.  

2. Turn OFF the HVAC controls.  

3. Place the A/C request switch in the OFF position.  

Does the A/C compressor clutch engage?

Go to 

Step 3

Go to Testing for 

Intermittent Conditions 

and Poor Connections in 

Wiring Systems

3

1. Turn OFF the ignition.  

2. Disconnect the A/C compressor clutch.  

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

4. Probe the supply voltage circuit of the A/C 

compressor clutch with a test lamp that is connected 
to ground.  

Does the test lamp illuminate?

Go to 

Step 4

Go to Step 8

4

Test the supply voltage circuit of the A/C compressor 
clutch for a short to voltage. Refer to Circuit Testing and 
to Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to 

Step 13

Go to Step 5

5

1. Turn OFF the ignition.  

2. Disconnect the A/C compressor clutch relay.  

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

4. Connect a test lamp between the control circuit and 

the ignition-3 voltage circuit of the A/C compressor 
clutch relay.  

Does the test lamp illuminate?

Go to 

Step 6

Go to Step 7

6

Test the control circuit of the A/C compressor clutch relay 
for a short to ground. Refer to Circuit Testing and to 
Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to 

Step 13

Go to Step 9

7

Inspect for poor connections at the A/C compressor clutch 
relay. Refer to Testing for Intermittent Conditions and 
Poor Connections and to Connector Repairs in Wiring 
Systems. 
Did you find and correct the condition?

Go to 

Step 13

Go to Step 10

Inspect for poor connections at the harness connector of the 
A/C compressor clutch. Refer to Testing for Intermittent 

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

BLOWER MOTOR ALWAYS ON 

Test Description 

The number below refers to the step number on the diagnostic table. 

4: The blower motor parameter must be commanded ON before an OFF command will function.  

Blower Motor Always On 

8

Conditions and Poor Connections and to Connector 
Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to 

Step 13

Go to Step 11

9

Inspect for poor connections at the harness connector of the 
powertrain control module (PCM). Refer to Testing for 
Intermittent Conditions and Poor Connections and to 
Connector Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to 

Step 13

Go to Step 12

10

Replace the A/C compressor clutch relay. 
Did you complete the replacement?

Go to 

Step 13

-

11

Replace the A/C compressor clutch. Refer to Compressor 
Clutch Plate/Hub Assembly Replacement in Heating, 
Ventilation and Air Conditioning. 
Did you complete the replacement?

Go to 

Step 13

-

12

Replace the PCM. Refer to Powertrain Control Module 
(PCM) Replacement in Engine Controls - 4.8L, 5.3L, 
6.0L.Did you complete the replacement?

IMPORTANT:

Program the PCM.

Go to 

Step 13

-

13

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

System 

OK

Go to Step 3

Step

Action

Values

Yes

No

Schematic Reference:HVAC Schematics 
Connector End View Reference: HVAC Connector End Views 
DEFINITION: The blower motor operates with the HVAC controls in the OFF position.

1

Did you perform the HVAC Diagnostic 
System Check?

-

Go to Step 2

Go to Diagnostic 

System Check - 

HVAC Systems - 

Automatic

2

1. Turn the ignition ON, with the 

engine OFF.  

2. Turn OFF the HVAC controls.  

-

Go to Testing for 

Intermittent Conditions 

and Poor Connections 

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

BLOWER MOTOR INOPERATIVE 

Blower Motor Inoperative 

Is the blower motor OFF?

in Wiring Systems

Go to Step 3

3

With a scan tool observe the Blower Motor 
PWM Speed parameter in the Heating and 
Air Conditioning data list. 
Does the scan tool indicate that the Blower 
Motor PWM Speed parameter is near the 
specified value?

0%

Go to Step 4

Go to Step 6

4

1. With a scan tool, command the 

Blower Motor parameter ON in the 
Heating and Air Conditioning Scan 
Tool Output Controls.  

2. Command the Blower Motor 

parameter OFF.  

Does the blower motor turn OFF?

-

Go to Step 6

Go to Step 5

5

Inspect for poor connections at the harness 
connector of the blower motor control 
processor. Refer to Wiring Repairs and 
Connector Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 9

Go to Step 7

6

Inspect for poor connections at the harness 
connector of the HVAC control module. 
Refer to Circuit Testing and Wiring 
Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 9

Go to Step 8

7

Replace the blower motor control 
processor. Refer to Blower Motor Control 
Processor Replacement . 
Did you complete the replacement?

-

Go to Step 9

-

8

Replace the HVAC control module. Refer 
to HVAC Control Module 
Replacement .Did you complete the 
replacement?

IMPORTANT:

Perform the recalibration procedure for 
the HVAC control module.

-

Go to Step 9

-

9

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

-

System OK

Go to Step 2

Step

Action

Yes

No

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

Schematic Reference:HVAC Schematics 
Connector End View Reference: HVAC Connector End Views 
DEFINITION: The blower motor is inoperative in all speed positions.

1

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic 

System Check - 

HVAC Systems - 

Automatic

2

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

2. Place the blower motor switch in each speed 

position.  

Does the blower motor operate in any of the speed 
positions?

Go to Blower 

Motor 

Malfunction

Go to Step 3

3

1. Turn OFF the ignition.  

2. Disconnect the blower motor connector.  

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

4. Connect a test lamp between the blower motor 

supply voltage circuit and the blower motor ground 
circuit.  

5. Place the blower motor switch in the maximum 

speed position.  

6. Place the air temperature switch to the warmest 

position.  

Does the test lamp illuminate?

Go to Step 10

Go to Step 4

4

1. Disconnect the blower motor control processor.  

2. Connect a test lamp between the battery positive 

voltage circuit and the ground circuit of the blower 
motor control processor.  

Does the test lamp illuminate?

Go to Step 8

Go to Step 5

5

Connect a test lamp between the battery positive voltage 
circuit of the blower motor control processor and a good 
ground. 
Does the test lamp illuminate?

Go to Step 7

Go to Step 6

6

Repair the battery positive voltage circuit of the blower 
motor control processor. Refer to Wiring Repairs in 
Wiring Systems. 
Did you find and correct the condition?

Go to Step 16

-

7

Repair the ground circuit of the blower motor control 
processor. Refer to Wiring Repairs in Wiring Systems. 
Did you complete the repair?

Go to Step 16

-

1. Connect a test lamp between the blower motor 

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2