Hummer H3. Manual — part 1256

AIR CONDITIONING (A/C) DIAGNOSTICS - PRESSURE ZONE C

Air Conditioning (A/C) Diagnostics - Pressure Zone C

Step

Action

Yes

No

DEFINITION: The low and the high side pressures are both higher than normal.

Restricted Condenser Air Flow

Cooling Fan Malfunction

Expansion Device Malfunction

1

Were you sent here from the A/C System
Performance Test?

Go to Step 2

Go to Air
Conditioning
(A/C) System
Performance
Test

2

1. Start the engine.

2. Turn ON the A/C.

3. Inspect for proper cooling fan

operation. Refer to Cooling System
Description and Operation .

Are the cooling fans ON and operating
properly?

Go to Step 3

Go to Step 5

3

Visually inspect for the following
conditions:

Damaged condenser cooling fins

Missing or misaligned air baffles

Restricted air flow

Do any of these conditions exist?

Go to Step 4

Go to Step 6

4

Repair the air flow restriction.
Is the action complete?

Go to Step 9

-

5

Repair the fault to the cooling fan
operation. Refer to Diagnostic System
Check - Vehicle .
Is the repair complete?

Go to Step 9

-

CAUTION:

2007 Hummer H3

2007 HVAC Heating, Ventilation and Air Conditioning - H3

6

Feel the liquid line on both sides of the
expansion device.Are the temperatures on
both sides of the expansion device similar?

Refer to Moving Parts and Hot Surfaces
Caution .

Go to Step 7

Go to Step 8

7

Replace the damaged or faulty thermal
expansion valve. Refer to Thermal
Expansion Valve Replacement (Left
Hand Drive) or Thermal Expansion
Valve Replacement (Right Hand
Drive).
Is the action complete?

Go to Step 9

-

8

1. Air is in the refrigerant system or the

system is overcharged. Refer to the
view screen on J 43600 ACR 2000
Air Conditioning Service Center for
foreign gas content in the refrigerant.
See Special Tools.

2. Recover and recharge the A/C

system. Refer to Refrigerant
Recovery and Recharging.

Is the action complete?

Go to Step 9

-

9

1. Record the low and high side

pressures and the instrument panel
outlet air temperature after you have
performed the repairs.

2. Compare the pressures and the

instrument panel outlet air
temperature to those listed in the A/C
Performance Chart. Refer to Air
Conditioning (A/C) System
Performance Test.

Are the readings within the specified
ranges listed in the A/C Performance
Chart?

Go to Step 10

Go to Air
Conditioning
(A/C) System
Performance
Test

2007 Hummer H3

2007 HVAC Heating, Ventilation and Air Conditioning - H3

AIR CONDITIONING (A/C) DIAGNOSTICS - PRESSURE ZONE D

Air Conditioning (A/C) Diagnostics - Pressure Zone D

10

Operate the system in order to verify the
repair.
Did you find and correct the condition?

System OK

Go to Symptoms
- HVAC
Systems -
Manual

Step

Action

Yes

No

DEFINITION: The low side pressure is lower than normal and the high side pressure is
higher than normal.

A restriction in the A/C system

Debris in the A/C system

1

Were you sent here from the A/C System
Performance Test?

Go to Step 2

Go to Air
Conditioning
(A/C) System
Performance
Test

2

Feel the liquid line before the expansion
device.Is the liquid line cold before the
expansion device?

CAUTION:

Refer to Moving Parts and Hot Surfaces
Caution .

Go to Step 3

Go to Step 8

3

Feel along the surfaces of the following
high side components:

The compressor discharge hose

The condenser

The liquid line between the condenser
and the expansion device

Did you detect an abrupt drop in
temperature along the surfaces of any of the
listed components?

Go to Step 7

Go to Step 4

1. Feel the liquid line at the expansion

2007 Hummer H3

2007 HVAC Heating, Ventilation and Air Conditioning - H3

4

device location for extreme cold,
possibly accompanied by heavy frost.

2. Feel along the liquid line beyond the

expansion device location for warm
temperature.

Is the liquid line extremely cold at the
expansion device location and warm
beyond the expansion device location?

Go to Step 11

Go to Step 5

5

Feel along the surfaces of the following
low side components:

The evaporator inlet tube between the
expansion device and the evaporator
core

The evaporator outlet tube between
the evaporator core and the
compressor suction hose

The compressor suction hose

Did you feel an abrupt temperature change
along the surfaces of any of the listed
components?

Go to Step 7

Go to Step 6

6

Feel along the surfaces of the low and the
high side components.

The evaporator inlet tube between the
expansion device and the evaporator
core

The evaporator outlet tube and the
compressor

The compressor suction hose

The compressor discharge hose

The condenser

The evaporator inlet tube between the
condenser and the expansion device

2007 Hummer H3

2007 HVAC Heating, Ventilation and Air Conditioning - H3