Hummer H2. Manual - part 1945

13

4. Turn ON the ignition, with the 

engine OFF.  

5. With a scan tool, observe the A/C 

Pressure Sensor parameter in the 
Powertrain data list.  

6. Compare the A/C high side 

pressure on the scan tool to the 
high side pressure on J 43600 .  

Are the high side pressure values within 
103 kPa (15 psi) of each other?

-

Go to Air 

Conditioning (A/C) 

System Performance 

Test in Heating, 

Ventilation and Air 

Conditioning

Go to Step 24

14

1. Start the engine.  

2. With a scan tool, command the 

A/C Permission to Granted and 
Withheld.  

Does the relay turn ON and OFF with 
each command?

-

Go to Step 15

Go to Step 19

15

1. Turn OFF the ignition.  

2. Test the battery positive voltage 

circuit of the A/C compressor 
clutch relay for a high resistance 
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 35

Go to Step 16

16

1. Turn OFF the ignition.  

2. Connect a 10-ampere fused 

jumper between the battery 
positive circuit of the A/C 
compressor relay and the A/C 
compressor supply voltage circuit. 

3. Disconnect the A/C compressor 

connector.  

4. Turn ON the ignition, with engine 

OFF.  

5. Connect a test lamp between the 

A/C compressor supply voltage 
circuit and the ground circuit of 
the A/C compressor.  

Does the test light illuminate?

-

Go to Step 25

Go to Step 17

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

17

Test the supply voltage circuit of the 
A/C compressor clutch for a high 
resistance 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 35

Go to Step 18

18

Test the ground circuit of the A/C 
compressor clutch for a high resistance 
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 35

Go to Step 22

19

1. Turn OFF the ignition.  

2. Disconnect the A/C compressor 

clutch relay.  

3. Turn ON the ignition, with the 

engine OFF.  

4. Probe the ignition 3 voltage circuit 

of the A/C compressor clutch 
relay with a test lamp that is 
connected to ground.  

Does the test lamp illuminate?

-

Go to Step 20

Go to Step 28

20

1. Start the engine.  

2. Connect a test lamp between the 

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

3. With a scan tool, command the 

A/C Permission to Granted.  

Does the test lamp illuminate?

-

Go to Step 22

Go to Step 21

21

1. Turn OFF the ignition.  

2. Test the A/C compressor clutch 

control circuit of the PCM for a 
high resistance 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 35

Go to Step 27

1. Turn OFF the ignition.  

2. Inspect for poor connections at the 

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

22

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 35

Go to Step 29

23

Inspect for poor connections at the 
harness connector of the A/C low 
pressure switch. 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 35

Go to Step 30

24

Inspect for poor connections at the 
harness connector of the A/C refrigerant 
pressure sensor. 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 35

Go to Step 31

25

Inspect for poor connections at the 
harness connector of the A/C 
compressor. 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 35

Go to Step 32

26

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 35

Go to Step 33

27

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 35

Go to Step 34

28

Repair the ignition 3 voltage circuit of 
the A/C compressor clutch relay. Refer 
to Wiring Repairs in Wiring Systems. 
Did you complete the repair?

-

Go to Step 35

-

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2

  

HVAC COMPRESSOR CLUTCH DOES NOT DISENGAGE 

Test Description 

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

2: These actions will disable the HVAC control module output to powertrain control module (PCM).  

HVAC Compressor Clutch Does Not Disengage 

29

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

-

Go to Step 35

-

30

Replace the A/C low pressure switch. 
Refer to Air Conditioning (A/C) Low 
Pressure Switch Replacement in 
Heating, Ventilation, and Air 
Conditioning. 
Did you complete the replacement?

-

Go to Step 35

-

31

Replace the A/C refrigerant pressure 
sensor. Refer to Air Conditioning 
(A/C) Refrigerant Pressure Sensor 
Replacement in Heating, Ventilation 
and Air Conditioning. 
Did you complete the replacement?

-

Go to Step 35

-

32

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 35

-

33

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

-

Go to Step 35

-

34 Replace the PCM. Refer to Powertrain 

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

IMPORTANT:

Program the PCM.

-

Go to Step 35

-

35

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

-

System OK

Go to Step 5

Step

Action

Yes

No

 

2004 Hummer H2 

2004 HVAC HVAC Systems - Automatic - Hummer H2