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