Hummer H2. Manual — part 1941

Go to Step 2

HVAC Systems -

Automatic

2

1. Install a scan tool.

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

3. With the scan tool, observe the appropriate Door

Actual parameter in the Heating and Air
Conditioning data list.

Does the scan tool indicate that the appropriate Door
Actual parameter is within the specified range?

5-250

counts

Go to

Diagnostic

Aids

Go to Step 3

3

1. Turn OFF the ignition.

2. Disconnect the appropriate HVAC door actuator.

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

4. With a scan tool, observe the appropriate Door

Actual parameter.

Does the scan tool indicate that the appropriate Door
Actual parameter is less than the specified value?

5

counts

Go to Step 4

Go to Step 10

4

1. Turn OFF the ignition.

2. Connect a 3-ampere fused jumper between the

5-volt reference circuit and the appropriate door
position signal circuit of the HVAC door
actuator.

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

4. With a scan tool, observe the appropriate Door

Actual parameter.

Does the scan tool indicate that the appropriate Door
Actual parameter is greater than the specified value?

230

counts

Go to Step 5

Go to Step 8

5

1. Disconnect the fused jumper.

2. Measure the voltage between the 5-volt

reference circuit and the low reference circuit of
the HVAC door actuator.

Does the voltage measure less than the specified
value?

5.5 V

Go to Step 6

Go to Step 7

6

1. Turn OFF the ignition.

2. Disconnect the negative battery cable.

3. Measure the resistance from the low reference

circuit of the HVAC door actuator to a good
ground.

5 ohm

2004 Hummer H2

2004 HVAC HVAC Systems - Automatic - Hummer H2

Does the resistance measure less than the specified
value?

Go to Step

12

Go to Step 11

7

Test the 5-volt reference circuit of the appropriate
HVAC door actuator 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

16

Go to Step 13

8

Test the 5-volt reference circuit of the appropriate
HVAC door actuator for a short to ground, 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

16

Go to Step 9

9

Test the appropriate door position signal circuit of the
HVAC door actuator for a short to ground, 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

16

Go to Step 13

10

Test the appropriate door position signal circuit of the
HVAC door actuator 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

16

Go to Step 13

11

1. Disconnect the HVAC control module.

2. Test the low reference circuit of the appropriate

HVAC door actuator 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

16

Go to Step 13

12

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

16

Go to Step 14

13

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

16

Go to Step 15

Replace the HVAC door actuator. Refer to the

IMPORTANT:

Perform the calibration procedure for HVAC door
actuators.

2004 Hummer H2

2004 HVAC HVAC Systems - Automatic - Hummer H2

DTC B0263, B0268, B0408, OR B0418

Circuit Description

The following DTC's are for the HVAC door actuators:

z

B0263 is for the mode actuator.

z

B0268 is for the recirculation actuator.

z

B0408 is for the left air temperature actuator.

z

B0418 is for the right air temperature actuator.

The HVAC control module controls the HVAC door actuators to regulate the airflow through the HVAC
system. Each actuator consists of a stepper motor, a logic circuit, and a potentiometer. The potentiometer inside
the door actuator allows the module to monitor the current position of the actuator drive shaft. The logic circuit
inside the actuators receives control signals from the HVAC control module and controls the internal stepper
motor. When a door positional change is required, the HVAC control module calculates a commanded door
position. The module compares the commanded door position to the actual door position and determines the
needed direction of motor rotation. The module applies a signal voltage to the door control circuit that is an
input to the internal logic circuit of the door actuator. A 5 volt signal increases the door position. A 0 volt signal
decreases the door position. When the commanded door position is equal to the actual door position, the HVAC
control module sends a 2.5 volt signal to the door actuator and motor rotation stops. The ignition 3 voltage
circuit provides source voltage to the logic circuit. The module provides ground to the actuator logic circuit
through the low reference circuit.

14

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?

-

Go to Step

16

-

15

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

-

Go to Step

16

-

16

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

Conditions for Running the DTC

z

Source voltage is 8.7-16.5 volts.

z

The ignition is ON.

z

The HVAC control module commands the actuator to move.

Conditions for Setting the DTC

The actual door position is not near the commanded door position.

Action Taken When the DTC Sets

The HVAC control module does not command the actuator to move for the remainder of the ignition cycle.

Conditions for Clearing the DTC

z

The DTC becomes history during the next ignition cycle in which the HVAC control module no longer
detects a stall condition.

z

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

z

The DTC can be cleared with a scan tool.

Diagnostic Aids

z

If the condition is not present refer to Testing for Intermittent Conditions and Poor Connections in
Wiring Systems.

z

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

{

A misaligned door actuator

{

Binding linkages

{

A binding door

{

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

Test Description

The numbers below refer to the step numbers on the diagnostic table.

2: Determines if the HVAC door actuator is stalled.

3: Applies control circuit voltages to the input of the HVAC door actuator.

DTC B0263, B0268, B0408, or B0418

Step

Action

Yes

No

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

Did you perform the HVAC Diagnostic System Check?

Go to Diagnostic

System Check -

2004 Hummer H2

2004 HVAC HVAC Systems - Automatic - Hummer H2