Hummer H2. Manual - part 1942

1

Go to Step 2

HVAC Systems - 

Automatic

2

1. Install a scan tool.  

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

3. With a scan tool, command the appropriate HVAC 

door actuator ON and OFF while observing the 
corresponding Door Actual parameter in the Heating 
and Air Conditioning Data List.  

Does the scan tool indicate that the value of the appropriate 
Door Actual parameter changes?

Go to 

Diagnostic 

Aids

Go to Step 3

3

1. Observe the appropriate HVAC door actuator drive 

shaft.  

2. Connect a 3 amp fused jumper wire between 

appropriate door control circuit at the HVAC control 
module and a good ground.  

3. Disconnect the fused jumper wire.  

4. Connect a 3 amp fused jumper wire between the 

appropriate door control circuit and the 5 volt reference 
circuit at the HVAC control module.  

Does the drive shaft of the appropriate HVAC door actuator 
rotate?

Go to Step 8

Go to Step 4

4

Test the door control circuit of the appropriate HVAC door 
actuator for a short to voltage, for a short to ground, or for an 
open. Refer to Circuit Testing and to Wiring Repairs in 
Wiring Systems. 
Did you find and correct the condition?

Go to Step 

12

Go to Step 5

5

1. Turn OFF the ignition.  

2. Disconnect the fused jumper wire.  

3. Disconnect the appropriate HVAC door actuator.  

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

5. Probe the ignition 3 voltage circuit of the appropriate 

HVAC door actuator with a test lamp that is connected 
to ground.  

Does the test lamp illuminate?

Go to Step 6

Go to Step 9

Inspect the appropriate door and the door actuator for the 
following conditions: 

z

A misaligned door actuator.  

z

Binding linkages  

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

DTC B1375 

Circuit Description 

6

z

A binding door  

z

An obstruction that prevents the HVAC door actuator 
from operating within the full range of motion  

 
Did you find and correct the condition?

Go to Step 

12

Go to Step 7

7

Inspect for poor connections at the harness connector of the 
appropriate HVAC door actuator. 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 

12

Go to Step 10

8

Inspect for poor connections at the harness connector of the 
HVAC control module. 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 

12

Go to Step 11

9

Repair the ignition 3 voltage circuit of the appropriate HVAC 
door actuator. Refer to Wiring Repairs in Wiring Systems. 
Did you complete the repair?

Go to Step 

12

-

10

Replace the appropriate HVAC door actuator. Refer to the 
appropriate replacement procedure: 

z

Recirculation Actuator Replacement  

z

Mode Actuator Replacement  

z

Air Temperature Actuator Replacement - Right  

z

Air Temperature Actuator Replacement - Left  

Did you complete the replacement?

IMPORTANT:

Perform the calibration procedure for HVAC door 
actuators.

Go to Step 

12

-

11

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

Go to Step 

12

-

12

1. Use the scan tool in order to clear the DTCs.  

2. Operate the vehicle according to the Conditions for 

Running in the DTC as specified in the supporting text. 

Does the DTC set again?

Go to Step 2

System OK

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

The ignition 3 voltage circuit is a discrete input to the HVAC control module. The HVAC control modules uses 
the input to determine that the ignition switch is in the RUN position. When the ignition switch is in the RUN 
position, ignition voltage is applied to the input. 

Conditions for Running the DTC 

z

Source voltage is 8.7-16.5 volts.  

z

The HVAC control module receives a RUN power mode message from the BCM over the class 2 serial 
data circuit.  

Conditions for Setting the DTC 

The HVAC control module does not detect ignition voltage on the ignition 3 voltage input. 

Action Taken When the DTC Sets 

The HVAC control module will continue to operate using the class 2 power mode messaging. 

Conditions for Clearing the DTC 

z

The DTC will become history if the HVAC control module no longer detects the condition that set the 
DTC.  

z

The history DTC will clear after 100 fault free ignition cycles.  

z

The DTC can be cleared with a scan tool.  

DTC B1375 

Step

Action

Yes

No

Schematic Reference: HVAC Schematics 
Connector End View Reference: HVAC Connector End Views

1

Did you perform the HVAC Diagnostic System Check?

Go to 

Step 2

Go to Diagnostic System 

Check - HVAC Systems - 

Automatic

2

1. Install a scan tool.  

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

3. Select the HVAC control module display DTC 

function on the scan tool.  

Does the scan tool indicate that B1375 is a current DTC?

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 HVAC control module.  

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

4. Probe the ignition 3 voltage circuit with a test lamp 

that is connected to a good ground.  

Go to 

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

DTC P0530 

Circuit Description 

The powertrain control module (PCM) monitors the high side refrigerant pressure via a A/C refrigerant pressure 
sensor. When the pressure is high the signal voltage is high. When the pressure is low the signal voltage is low. 
When pressure is too high the PCM will not allow the A/C compressor clutch to engage. 

Conditions for Running the DTC 

The PCM detects an A/C request. 

Conditions for Setting the DTC 

z

The A/C refrigerant pressure sensor signal is less than 0.1 volts for 5 seconds.  

z

The A/C refrigerant pressure sensor signal is greater than 4.9 volts for 5 seconds.  

Action Taken When the DTC Sets 

The malfunction indicator lamp (MIL) will not illuminate. 

Conditions for Clearing the DTC 

z

The DTC will become history if the PCM no longer detects a failure.  

z

The history DTC will clear after 40 fault-free ignition cycles.  

z

The DTC can be cleared with a scan tool. 

Does the test lamp illuminate?

Step 4

Go to Step 5

4

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 7

Go to Step 6

5

Repair the ignition 3 voltage circuit. Refer to Wiring 
Repairs in Wiring Systems. 
Did you complete the repair?

Go to 

Step 7

-

6

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

Go to 

Step 7

-

7

1. Use the scan tool in order to clear the DTCs.  

2. Operate the vehicle within the Conditions for Running 

the DTC as specified in the supporting text.  

Does the DTC reset?

Go to 

Step 3

System OK

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2