Hummer H3. Manual — part 1292

5

6. Record the ambient

temperature at the vehicle.

7. Record readings of the low

and high side STATIC
pressures.

8. Compare the low and the high

side pressure values with the
allowable limits for the
recorded ambient air
temperature.

Are the low and the high side
pressure values within the
allowable limits for the recorded
ambient air temperature. Are the
pressure values within 103 kPa (15
psi) of each other?

Above

24°C

(75°F)

483 kPa

(70 psi)

Above

33°C

(90°F)

690 kPa

(100 psi)

Go to Step 6

Go to Leak
Testing

6

1. Disconnect the A/C

compressor relay.

2. Probe the battery positive

voltage circuit of the A/C
compressor clutch relay with
a test lamp connected to a
good ground.

Does the test lamp illuminate?

-

Go to Step 7

Go to Step

18

7

Connect a 10-amp fused jumper
between the battery positive
voltage circuit and the A/C
compressor clutch supply voltage
circuit of the A/C compressor
clutch relay.
Does the A/C compressor clutch
engage?

-

Go to Step 19

Go to Step

13

IMPORTANT:

Access the evaporator temperature
sensor gray control circuits and
module with 2-way connector to BCM
and HVAC control module behind the

2007 Hummer H3

2007 HVAC HVAC - Manual - H3

8

1. Disconnect the evaporator

temperature sensor at the 2-
wire connector running from
the evaporator temperature
control circuits to the HVAC
control module and BCM
behind the glove box.

2. Connect a test light between

the A/C request circuit of the
HVAC control module and
the BCM at the 2-wire
connector of the evaporator
temperature sensor.

Does the A/C compressor engage?

glove box.

-

Go to Step 9

Go to Step

11

9

1. With a 3-amp fused jumper

attached between the BCM
and the HVAC control
module A/C request circuits
at the 2-wire evaporator
temperature sensor behind the
glove box.

2. Check the resistance of the 2

gray evaporator temperature
sensor circuits at the
evaporator temperature
sensor behind the glove box.

3. Start the engine.

Does the resistance value stay
within the specified value range

IMPORTANT:

Access the evaporator temperature
sensor gray control circuits and
module with 2-way connector to BCM
and HVAC control module behind the
glove box.

Temperature

Minimum

14.9°C

(58.82°F) -

Resistance

Minimum

15651 ohms

Temperature

Maximum

30.1°C

(86.18°F) -

Resistance

Maximum

8190 ohms

Go to Step

2007 Hummer H3

2007 HVAC HVAC - Manual - H3

even after compressor engagement?

Go to Step 25

10

10

1. With a 3-amp fused jumper

attached between the BCM
and the HVAC control
module A/C request circuits
at the 2-wire evaporator
temperature sensor behind the
glove box.

2. Cut the 2 gray evaporator

temperature sensor circuits no
less than 2 inches from the
evaporator temperature
sensor module behind the
glove box.

3. Start the engine.

4. Check the resistance of the 2

gray wires at the evaporator
temperature sensor coming
out of the evaporator core at
the HVAC module.

Does the resistance value move
from the specified value range
when the compressor is engaged?

IMPORTANT:

Access the evaporator temperature
sensor gray control circuits and
module with 2-way connector to BCM
and HVAC control module behind the
glove box.

Temperature

Minimum

14.9°C

(58.82°F) -

Resistance

Minimum

15651 ohms

Temperature

Maximum

30.1°C

(86.18°F) -

Resistance

Maximum

8190 ohms

Go to Step 25

Go to Step

26

11

1. Disconnect the evaporator

temperature sensor at the 2-
wire pinout running to the
HVAC control module

IMPORTANT:

Access the evaporator temperature
sensor control circuits and module
through the glove box.

12 V

2007 Hummer H3

2007 HVAC HVAC - Manual - H3

behind the radio.

2. Probe the A/C request signal

circuit of the HVAC control
module with a DMM
connected to a good ground.

Does the DMM indicate at least
the specified value?

Go to Step 12

Go to Step

15

12

1. Connect a 3-amp fused

jumper between the A/C
request signal circuit of the
HVAC control module and
the A/C request signal circuit
of the BCM.

2. Observe the A/C Request

Signal parameter.

Does the scan tool indicate the A/C
Request Signal parameter is Yes?

-

Go to Step 20

Go to Step

17

13

Test the ground circuit of the A/C
compressor clutch for a high
resistance or for an open. Refer to
Circuit Testing and Wiring
Repairs .
Did you find and correct the
condition?

-

Go to Step 30

Go to Step

14

14

Test the supply voltage circuit of
the A/C compressor clutch for a
high resistance or for an open.
Refer to Circuit Testing and
Wiring Repairs .
Did you find and correct the
condition?

-

Go to Step 30

Go to Step

23

15

Test the A/C request signal circuit
of the HVAC control module for a
short to ground, a high resistance
and for an open. Refer to Circuit
Testing and Wiring Repairs .
Did you find and correct the

-

Go to Step

2007 Hummer H3

2007 HVAC HVAC - Manual - H3