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