Hummer H2. Manual - part 1947

8

speed control circuit and the battery positive 
voltage circuit of the blower motor control 
processor.  

2. Observe the test lamp.  

3. Place the blower motor switch from the minimum 

speed position to the maximum speed position.  

Does the test lamp increase intensity when the blower 
speed is increased?

Go to Step 11

Go to Step 9

9

Test the blower motor speed control circuit of the blower 
motor control processor for an open, short to ground, or 
short to voltage. Refer to Circuit Testing and Wiring 
Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to Step 16

Go to Step 12

10

Inspect for poor connections at the harness connector of 
the blower motor. Refer to Testing for Intermittent 
Conditions and Poor Connections and Connector 
Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to Step 16

Go to Step 13

11

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

Go to Step 16

Go to Step 14

12

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

Go to Step 16

Go to Step 15

13

Replace the blower motor. Refer to Blower Motor 
Replacement in Heating, Ventilation and Air 
Conditioning. 
Did you complete the replacement?

Go to Step 16

-

14

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

Go to Step 16

-

15

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 16

-

16

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

System OK

Go to Step 2

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

BLOWER MOTOR MALFUNCTION 

Test Description 

2: This step verifies that the HVAC control module Fan Up Switch parameter matches the requested state 
of the blower motor switch.  

3: This step verifies that the HVAC control module Fan Down Switch parameter matches the requested 
state of the blower motor switch.  

Blower Motor Malfunction 

Step

Action

Values

Yes

No

Schematic Reference:HVAC Schematics 
Connector End View Reference: HVAC Connector End Views 
DEFINITION: The blower motor operates in at least one speed 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 ON the ignition, with the engine 

OFF.  

2. With a scan tool, observe the Fan Up 

Button parameter in the Heating and Air 
Conditioning data list.  

3. Activate the fan up switch.  

Does the scan tool indicate that the Fan Up 
Button parameter changes state?

-

Go to Step 3

Go to Step 10

3

1. With a scan tool, observe the Fan Down 

Button parameter in the Heating and Air 
Conditioning data list.  

2. Activate the fan down switch.  

Does the scan tool indicate that the Fan Down 
Button parameter changes state?

-

Go to Step 4

Go to Step 10

4

Place the blower motor switch in each speed 
position. 
Does the blower motor operate at the desired 
speeds?

-

Go to Testing for 

Intermittent 

Conditions and Poor 

Connections in Wiring 

Systems

Go to Step 5

5

1. Disconnect the harness connector of the 

blower motor control processor.  

2. Measure the voltage between the battery 

positive voltage circuit and the ground 
circuit of the blower motor control 

10-14 

V

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

processor.  

Does the voltage measure within the specified 
range?

Go to Step 6

Go to Step 8

6

1. Connect the blower motor control 

processor.  

2. Disconnect the harness connector of the 

HVAC control module.  

3. Measure the voltage on the blower 

motor speed control circuit.  

Does the voltage measure within the specified 
range?

4.5-5.5 

V

Go to Step 9

Go to Step 7

7

Test the control circuit of the blower motor 
control processor for a high resistance. Refer 
to Circuit Testing and Wiring Repairs in 
Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 14

Go to Step 9

8

Test the battery positive voltage circuit of the 
blower motor control processor for a high 
resistance. Refer to Circuit Testing and 
Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 14

Go to Step 11

9

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

-

Go to Step 14

Go to Step 12

10

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

-

Go to Step 14

Go to Step 13

11

Repair a high resistance in the ground circuit 
of the blower motor control processor. Refer 
to Circuit Testing in Wiring Systems. 
Did you complete the repair?

-

Go to Step 14

-

12

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

-

Go to Step 14

-

IMPORTANT:

Perform the recalibration procedure for the 

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

TOO HOT IN VEHICLE 

Diagnostic Aids 

z

The condition may be intermittent. Refer to Testing for Intermittent Conditions and Poor 
Connections in Wiring Systems.  

z

The air temperature actuators can be calibrated. Refer to Re-Calibrating Actuators .  

z

If the door actuators are out of the calibrated range the auto recirculation function will not work. The 
vehicle operator must place the HVAC controls to the recirculation position manually. Ensure to perform 
an actuator recalibration to correct this condition.  

Test Description 

The numbers below refer to the step numbers on the diagnostic table. 

6: Ambient air temperature must be above 3° C (38° F) in order for this A/C compressor test to be run.  

8: This step ensures that the lower air temperature sensors operate properly. The LH and RH Heater Duct 
Actual parameter count values should lower as the air temperature of the ducts get warmer. If there is a 
high resistance in either of the air temperature sensors circuits or the sensor itself then the count value of 
the effected sensor would remain high.  

9: This step ensures that the upper air temperature sensors operate properly. The LH and RH AC Duct 
Actual parameter count values should lower as the air temperature of the ducts get warmer. If there is a 
high resistance in either of the air temperature sensors circuits or the sensor itself then the count value of 
the effected sensor would remain high.  

14: Use the following table to determine that the recorded scan tool values are within range for the 
recorded probe temperatures of the J 43600 .  

Too Hot in Vehicle 

13 Replace the HVAC control module. Refer to 

HVAC Control Module Replacement .Did 
you complete the replacement?

HVAC control module.

-

Go to Step 14

-

14

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

-

System OK

Go to Step 2

Temperature ° C

Temperature ° F

Scan Tool Display

0-4

32-40

206-175 counts

5-9

41-49

194-161 counts

10-14

50-58

180-145 counts

15-19

59-67

166-133 counts

20-24

68-76

150-119 counts

25-29

77-85

136-106 counts

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2