Hummer H2. Manual - part 1949

Did you find and correct the condition?

Go to Step 31

Go to Step 26

19

Test the ground circuit of the inside air temperature 
sensor for an open or high resistance. Refer to Circuit 
Testing and Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to Step 31

Go to Step 23

20

1. Turn OFF the ignition.  

2. Disconnect the inside air temperature sensor 

assembly.  

3. Place the temperature probe of the J 43600 near 

the inside air temperature sensor assembly.  

4. Record the probe temperature.  

5. Measure the resistance of the inside air temperature 

sensor. Refer to Sensor Resistance Table .  

Does the resistance measure within the specified range ?

Go to Step 22

Go to Step 23

21

Test the signal circuit and the low reference circuit of the 
appropriate air temperature sensor for a high resistance. 
Refer to Circuit Testing and Wiring Repairs in Wiring 
Systems. 
Did you find and correct the condition?

Go to Step 31

Go to Step 24

22

Test the signal circuit and the low reference circuit of the 
inside air temperature sensor assembly for a high 
resistance. Refer to Circuit Testing and Wiring Repairs
in Wiring Systems. 
Did you find and correct the condition?

Go to Step 31

Go to Step 26

23

Inspect for poor connections at the harness connector of 
the inside air temperature sensor assembly. 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 31

Go to Step 29

24

Inspect for poor connections at the harness connector of 
the appropriate air temperature sensor. 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 31

Go to Step 27

25

Inspect for poor connections at the harness connector of 
the sunload sensor assembly. 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 31

Go to Step 28

26

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. 

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

TOO COLD 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 .  

Test Description 

The numbers below refers to the step numbers in the diagnostic table. 

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 

Did you find and correct the condition?

Go to Step 31

Go to Step 30

27

Replace the appropriate air temperature sensor. Refer to 
one of the following procedures: 

z

Air Temperature Sensor Replacement - Upper 
Right  

z

Air Temperature Sensor Replacement - Upper 
Left  

z

Air Temperature Sensor Replacement - Lower 
Left  

z

Air Temperature Sensor Replacement - Lower 
Right  

 
Did you complete the replacement?

Go to Step 31

-

28

Replace the sunload sensor. Refer to Sun Load Sensor 
Replacement . 
Did you complete the replacement?

Go to Step 31

-

29

Replace the inside air temperature sensor assembly. Refer 
to Inside Air Temperature Sensor Assembly 
Replacement . 
Did you complete the replacement?

Go to Step 31

-

30

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

Go to Step 31

-

31

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

System OK

Go to Step 3

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

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.  

15: Use the following table to determine that the recorded scan tool values are within range for the 
recorded probe temperatures.  

Too Cold in Vehicle 

Too Cold in Vehicle 

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

30-34

86-94

121-93 counts

35-39

95-103

107-81 counts

40-44

104-112

94-69 counts

45-49

113-121

83-59 counts

50-54

122-130

72-51 counts

55-59

131-139

63-44 counts

60-64

140-148

55-37 counts

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics 
Connector End View Reference: HVAC Connector End Views 
DEFINITION: The temperature can not be adjusted, or heating is insufficient.

1

Did you perform the HVAC Diagnostic System 
Check?

-

Go to Step 2

Go to Diagnostic 

System Check - 

HVAC Systems - 

Automatic

2

1. Recalibrate actuators. Refer to Re-

Calibrating Actuators .  

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

3. Observe the in Heating and Air 

Conditioning.  

IMPORTANT:

If during this diagnostic procedure the HVAC 
control module is disconnected a recalibration 
of actuators must be performed to avoid 
misdiagnosis.

-

Go to 

Diagnostic 

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

Does the scan tool display any DTC B0229, 
B0414, B0424 or B3770?

Trouble Code 

(DTC) List

Go to Step 3

3

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

2. Turn ON the HVAC control module.  

3. Place the mode switch in the PANEL 

position.  

4. Place the blower motor switch in each speed 

position.  

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

-

Go to Step 4

Go to Blower Motor 

Inoperative

4

Does the blower motor operate in all desired speed 
positions?

-

Go to Step 5

Go to Blower Motor 

Malfunction

5

1. Place the recirculation switch in the ON 

position.  

2. Observe the recirculation door.  

3. Place the recirculation switch in the OFF 

position.  

Does the recirculation door move from the 
recirculation position to the outside air position?

-

Go to Step 6

Go to Air 

Recirculation 

Malfunction

6

1. Start the engine.  

2. Place the A/C request switch in the ON 

position.  

3. Observe the A/C compressor clutch.  

4. Place the A/C request switch in the OFF 

position.  

Does the A/C compressor clutch disengage?

-

Go to Step 7

Go to HVAC 

Compressor Clutch 

Does Not Disengage

7

Perform the Heating Performance Diagnostic. 
Refer to Heating Performance Diagnostic . 
Did you find and correct the condition?

-

Go to Step 29

Go to Step 08

8

1. Start the engine.  

2. Wait until engine coolant temperature 

reaches its normal operating temperature.  

3. Place the mode switch to the Floor position.  

4. Place the drivers air temperature switch to 

the warmest position.  

5. With a scan tool, observe the right and left 

Heater Duct Actual and Heater Duct Desired 
parameters.  

-

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2