Hummer H3. Manual — part 1296

Schematic Reference: HVAC Schematics
DEFINITION: The temperature cannot be adjusted or the cooling is
insufficient during A/C operation.

1

Did you review the HVAC
operation and perform the
necessary inspections?

-

Go to Step

2

Go to
Symptoms -
HVAC
Systems -
Manual

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 at all?

-

Go to Step

3

Go to
Blower
Motor
Malfunction

3

Does the blower motor
operate correctly for each
speed position?

-

Go to Step

4

Go to
Blower
Motor
Malfunction

4

Is the HVAC control
assembly inoperative?

-

Go to Step

15

Go to Step 5

5

Does the Too Hot in Vehicle
concern occur when A/C
cooling is desired?

-

Go to Step

6

Go to Step 8

6

1. Start the engine.

2. Place the blower motor

switch in the maximum
speed position.

3. Place the A/C request

switch in the ON
position.

4. Place the air

IMPORTANT:

For A/C compressor operation,
the ambient air temperature
must be above 3°C (38°F).

-

2007 Hummer H3

2007 HVAC HVAC - Manual - H3

temperature switch in
the coldest position.

Does the A/C compressor
operate?

Go to Step

7

Go to
HVAC
Compressor
Clutch Does
Not Engage

7

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

22

Go to Step 8

8

1. Observe the drive shaft

of both air temperature
actuators.

2. Adjust the air

temperature switch.

Does the drive shaft of both
air temperature actuators
rotate?

-

Go to Step

9

Go to Step

10

9

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

A misaligned air
temperature actuator.

Broken linkages or
binding linkages

A broken air
temperature door or a
binding air temperature
door.

An obstruction that
prevents the air
temperature door from

-

2007 Hummer H3

2007 HVAC HVAC - Manual - H3

operating within the full
range of motion.

Missing seals to the air
temperature door

Misaligned seals to the
air temperature door.

Did you find and correct the
condition?

Go to Step

22

Go to
Testing for
Intermittent
Conditions
and Poor
Connections

10

Test the position signal
circuit of the appropriate
temperature actuator for an
open or for a high resistance.
Refer to Circuit Testing and
to Wiring Repairs .
Did you find and correct the
condition?

-

Go to Step

22

Go to Step

11

11

Test the low reference circuit
of the appropriate
temperature actuator for an
open or for a high resistance.
Refer to Circuit Testing and
to Wiring Repairs .
Did you find and correct the
condition?

-

Go to Step

22

Go to Step

12

12

Test the 5-volt reference
circuit of the appropriate
temperature actuator for an
open or for a high resistance.
Refer to Circuit Testing and
to Wiring Repairs .
Did you find and correct the
condition?

-

Go to Step

22

Go to Step

13

1. Turn OFF the ignition.

2. Reconnect the

appropriate temperature
actuator.

2007 Hummer H3

2007 HVAC HVAC - Manual - H3

13

3. Turn ON the ignition

with the engine OFF.

4. Connect a test lamp

between temperature
door control A and
temperature door
control B circuits of the
appropriate temperature
actuator connector.

5. Place the temperature

switch in the cold
position.

6. Place the mode switch

in the hot position.

Does the test lamp illuminate
in both positions?

-

Go to Step

17

Go to Step

14

14

Test the temperature door
control A and temperature
door control B circuits of the
appropriate temperature
actuator for an open, a high
resistance, a short to ground
or a short to voltage. Refer to
Circuit Testing and to
Wiring Repairs .
Did you find and correct the
condition?

-

Go to Step

22

Go to Step

19

15

Test the ignition 3 voltage
circuit of the HVAC control
module for an open or for a
high resistance. Refer to
Circuit Testing and to
Wiring Repairs .
Did you find and correct the
condition?

Go to Step 22

Go to

Step 16

Test the ground circuit of the
HVAC control module for an

2007 Hummer H3

2007 HVAC HVAC - Manual - H3