Content .. 1946 1947 1948 1949 ..

Hummer H2. Manual - part 1948

Too Hot in Vehicle

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

Yes

Schematic Reference: HVAC Schematics
Connector End View Reference: HVAC Connector End Views
DEFINITION: Temperature can not be adjusted, or cooling insufficient during A/C operation.

Did you perform the HVAC Diagnostic System Check?

Go to Step 2

Go to Diagnostic

System Check -

HVAC Systems -

Automatic

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.

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

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

Trouble Code

(DTC) List

Go to Step 3

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 speed?

Go to Step 4

Go to Blower Motor

Inoperative

Does the blower motor operate in each speed?

Go to Step 5

Go to Blower Motor

Malfunction

1. Place the mode switch in the PANEL position.

2. Place the recirculation switch in the ON position.

3. Observe the recirculation door.

4. Place the recirculation switch in the OFF position.

Does the recirculation door move from the recirculation

Go to Air

Recirculation

2004 Hummer H2

2004 HVAC HVAC Systems - Automatic - Hummer H2

position to the outside air position?

Go to Step 6

Malfunction

1. Start the engine.

2. Observe the A/C compressor clutch.

3. Place the A/C request switch in the ON position.

Does the A/C compressor engage?

Go to Step 7

Go to HVAC

Compressor Clutch

Does Not Engage

Perform the refrigerant system performance test. Refer to
Air Conditioning (A/C) System Performance Test .
Did you find and correct the condition?

Go to Step 31

Go to Step 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.

6. Wait 3 minutes to allow the duct air temperature to

stabilize.

Do both of the Heater Duct Actual parameter values
increase within 15 Counts of the Heater Duct Desired
parameter?

Go to Step 9

Go to Step 21

1. Place the mode switch to the Panel position.

2. Place the drivers air temperature switch to the

warmest position.

3. With a scan tool, observe the right and left AC

Duct Actual and AC Duct Desired parameters.

4. Wait 3 minutes to allow the duct air temperature to

stabilize.

Do both of the AC Duct Actual parameter values increase
within 15 Counts of the AC Duct Desired parameter?

Go to Step 10

Go to Step 21

Check the air temperature sensors for proper installation.
Refer to the following procedures:

Air Temperature Sensor Replacement - Upper
Right

Air Temperature Sensor Replacement - Upper
Left

Air Temperature Sensor Replacement - Lower
Left

2004 Hummer H2

2004 HVAC HVAC Systems - Automatic - Hummer H2

Air Temperature Sensor Replacement - Lower
Right

Inside Air Temperature Sensor Assembly
Replacement

Did you find and correct the condition?

Go to Step 31

Go to Step 11

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

2. Inspect for air flow through the inside air

temperature sensor assembly by placing a 5 cm (2
in) square piece of paper over the sensor air inlet.

Does the paper stay in place?

Go to Step 12

Go to Step 17

1. Install a scan tool.

2. With a scan tool, observe the Left Solar Sensor and

Right Solar Sensor parameters in the Body Control
Module data list.

3. Direct a light source at the left and right sides of

the sunload sensor assembly.

Does the scan tool indicate that the values of the Left
Solar Sensor and the Right Solar Sensor parameters
change?

Go to Step 13

Go to Step 25

1. Place the temperature probe of the J 43600 near

the inside air temperature sensor assembly.

2. With a scan tool, observe the Inside Air Temp

parameter in the Heating and Air Conditioning
Data list.

Does the scan tool indicate that the sensor temperature is
within 3° C (5° F) of the thermometer temperature?

Go to Step 14

Go to Step 20

1. Start the engine.

2. Place the blower motor switch in the maximum

speed position.

3. Place the left and right air temperature switches in

the FULL COLD positions.

4. Place the mode switch in the bi-level position.

5. Wait 3 minutes to allow the discharge air

temperatures to stabilize.

6. With a scan tool, record the values of the following

parameters in the Heating and Air Conditioning
data list:

2004 Hummer H2

2004 HVAC HVAC Systems - Automatic - Hummer H2

LH AC Duct Actual

LH Heater Duct Actual

RH AC Duct Actual

RH Heater Duct Actual

7. With the temperature probes of the J 43600 ,

record the air temperatures near the following
sensors:

The left upper air temperature sensor

The left lower air temperature sensor

The right upper air temperature sensor

The right lower air temperature sensor

Are the parameter values within the specified range for
the recorded air temperatures?

Go to Diagnostic

Aids

Go to Step 15

1. Turn OFF the ignition.

2. Disconnect the suspect air temperature sensor.

3. Place the temperature probe of the J 43600 near

the air temperature sensor.

4. Record the probe temperature.

5. Measure the resistance of the air temperature

sensor. Refer to the Sensor Resistance Table .

Does the resistance measure within the specified range ?

Go to Step 16

Go to Step 24

Test the signal circuit and the low reference circuit of the
suspect 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 26

1. Turn the ignition OFF.

2. Disconnect the inside air temperature sensor

assembly.

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

4. Probe the fan motor supply voltage circuit of the

inside air temperature sensor assembly with a test
lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 19

Go to Step 18

Test the fan motor supply voltage circuit of the inside air
temperature sensor assembly for an open, a high
resistance, or a short to ground. Refer to Circuit Testing
and Wiring Repairs in Wiring Systems.

2004 Hummer H2

2004 HVAC HVAC Systems - Automatic - Hummer H2

Content .. 1946 1947 1948 1949 ..