Hummer H3. Manual — part 1255

lower than normal.

Malfunctioning A/C Compressor

Refrigerant Under Charge

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

After continued operation of the A/C
system, do the low and the high side
pressures equalize or become static?

Go to Step 5

Go to Step 3

3

1. Refer to the pressures recorded during

the A/C System Performance Test.

2. Inspect for the following conditions:

The low side pressure is equal to
or greater than the specified
pressure range of the A/C
Performance Table. Refer to Air
Conditioning (A/C) System
Performance Test .

The high side pressure is less
than the specified pressure range
of the A/C Performance Table.
Refer to Air Conditioning
(A/C) System Performance
Test .

The low side refrigerant line at
the compressor feels cool-to-
warm.

The high side refrigerant line at
the compressor feels warm-to-
hot.

CAUTION:

Refer to Moving Parts and Hot
Surfaces Caution .

2007 Hummer H3

2007 HVAC Heating, Ventilation and Air Conditioning - H3

Do the listed conditions exist?

Go to Step 5

Go to Step 4

4

1. Refer to the pressures recorded during

the A/C System Performance Test.

2. Inspect for the following conditions:

The low side pressure is greater
than the specified pressure range
of the A/C Performance Table.
Refer to Air Conditioning
(A/C) System Performance
Test .

The high side pressure is less
than the specified pressure range
of the A/C Performance Table.
Refer to Air Conditioning
(A/C) System Performance
Test .

The low side refrigerant line at
the compressor feels warm.

The high side refrigerant line at
the compressor feels warm-to-
hot.

Do the listed conditions exist?

CAUTION:

Refer to Moving Parts and Hot
Surfaces Caution .

Go to Step 5

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

5

The A/C system has a low refrigerant
charge.
Evacuate and recharge the A/C system.
Refer to Refrigerant Recovery and
Recharging.
Is the action complete?

Go to Step 6

-

1. After you perform the repairs, record

the following:

The low and the high side
pressures

2007 Hummer H3

2007 HVAC Heating, Ventilation and Air Conditioning - H3

6

The instrument panel outlet air
temperature

2. Compare the pressures and the

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
found on the A/C Performance Chart?

Go to Step 13

Go to Step 7

7

The A/C compressor is malfunctioning.
Remove the expansion device and inspect
for contamination. Refer to Thermal
Expansion Valve Replacement (Left
Hand Drive) or Thermal Expansion
Valve Replacement (Right Hand Drive).
Did you find metal flakes on the expansion
device?

Go to Step 9

Go to Step 8

8

Inspect the expansion device for a brown,
powdery residue indicating desiccant in the
A/C system.
Is a brown, powdery residue present?

Go to Step 11

Go to Step 12

9

1. Remove the suction and the discharge

lines from the compressor. Refer to
Suction Hose Replacement (Left
Hand Drive) or Suction Hose
Replacement (Right Hand Drive)
and to Discharge Hose
Replacement.

2. Inspect for metal flake contamination

at the line connections and the
compressor ports.

Is metal flake contamination present?

Go to Step 10

Go to Step 12

1. Replace the A/C compressor. Refer to

Compressor Replacement.

2. Replace the thermal expansion valve.

Refer to Thermal Expansion Valve

2007 Hummer H3

2007 HVAC Heating, Ventilation and Air Conditioning - H3

10

Replacement (Left Hand Drive) or
Thermal Expansion Valve
Replacement (Right Hand Drive).

3. Evacuate and recharge the A/C

system. Refer to Refrigerant
Recovery and Recharging.

Is the action complete?

Go to Step 13

-

11

1. Flush the A/C system. Refer to

Flushing.

2. Replace the thermal expansion valve.

Refer to Thermal Expansion Valve
Replacement (Left Hand Drive) or
Thermal Expansion Valve
Replacement (Right Hand Drive).

3. Replace the A/C compressor. Refer to

Compressor Replacement.

4. Replace the receiver dehydrator.

Refer to Receiver Dehydrator
Replacement.

5. Evacuate and recharge the A/C

system. Refer to Refrigerant
Recovery and Recharging.

Is the action complete?

Go to Step 13

-

12

1. Replace the A/C compressor. Refer to

Compressor Replacement.

2. Evacuate and recharge the A/C

system. Refer to Refrigerant
Recovery and Recharging.

Is the action complete?

Go to Step 13

-

13

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

System OK

Go to Symptoms
- HVAC
Systems -
Manual

2007 Hummer H3

2007 HVAC Heating, Ventilation and Air Conditioning - H3