Hummer H2. Manual - part 1963

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To prevent false diagnosis, thoroughly clean any residual dye from the service port with a rag and the 
approved fluorescent dye cleaner J 43872 . See Special Tools and Equipment .  

Halogen Leak Detector 

Ensure that the vehicle has at least 0.45 kg (1 lb) of refrigerant in the A/C refrigeration system in order to 
perform a leak test. Refer to Refrigerant Recovery and Recharging for recharging the A/C system. 

Clean and dry all surfaces in order to prevent a false warning. Liquids will damage the detector. 

Follow the instructions supplied with the J 39400-A . See Special Tools and Equipment . 

AIR CONDITIONING (A/C) SYSTEM PERFORMANCE TEST 

The following test measures the A/C system operating efficiency by comparing: 

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The ambient air temperature  

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The ambient air humidity  

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The pressure at the high-pressure side of the refrigeration system  

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The pressure at the low-pressure side of the refrigeration system  

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The temperature of the air being discharged into the passenger compartment  

Test Description 

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

1: This step determines if there is enough refrigerant in the A/C system in order to operate the system 
without damage.  

2: This step measures the performance of the A/C system.  

3: This step is to allow for vehicle variations as well as high ambient air temperatures.  

CAUTION: Do not operate the detector in a combustible atmosphere since its sensor 

operates at high temperatures or personal injury and/or damage to the 
equipment may result.

IMPORTANT: Halogen leak detectors are sensitive to the following items: 

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Windshield washing solutions  

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Many solvents and cleaners  

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Some adhesives used in the vehicle  

IMPORTANT: Follow a continuous path in order to ensure that you will not miss any possible 

leaks. Test all areas of the system for leaks.

 

2004 Hummer H2 

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

  

Air Conditioning (A/C) System Performance Test

Step

Action

Values

Yes

No

IMPORTANT:

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The ambient air temperature must be at least 16° C (60° F).  

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Do not induce additional air flow across the front of the vehicle during the test.  

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If you were sent here from a DTC diagnostic table, clear the DTC upon completion of this test. 

1

1. Park the vehicle inside or in the shade.  

2. Open the windows in order to ventilate 

the interior of the vehicle.  

3. If the A/C system was operating, allow 

the A/C system to equalize (about 2 
minutes).  

4. Ensure that the ignition key is in the 

OFF position.  

5. Install the J 43600 ACR 2000 Air 

Conditioning service center. See Special 
Tools and Equipment .  

6. Record the ambient air temperature 

displayed on the J 43600 . See Special 
Tools and Equipment .  

7. Record readings of the low and high 

side STATIC pressures.  

Are both the low and high side pressures 
within the specified value?

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Above 
16° C 
(60° F) - 
345 kPa 
(50 psi)  

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Above 
24° C 
(75° F) - 
483 kPa 
(70 psi)  

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Above 
33° C 
(90° F) - 
690 kPa 
(100 psi) 

Go to Step 2

Go to Leak 

Testing

1. Close the vehicle doors and windows.  

2. Open the driver door window 13-15 cm 

(5-6 inches).  

3. Set the HVAC control to the following 

positions: 

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The A/C ON  

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The blower control to the highest 
position  

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The HVAC control assembly to 
discharge air through the A/C 
outlets  

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Recirculation Mode  

IMPORTANT:

Record the relative humidity and the 
ambient air temperature AT THE TIME 
OF THE TEST.

 

2004 Hummer H2 

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

  

2

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The temperature control to the 
coldest position  

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All A/C outlets OPEN  

4. Install the temperature probes to the J 

43600 in the left and right center A/C air 
outlets. See Special Tools and 
Equipment .  

5. Apply the parking brake.  

6. Place the transaxle/transmission in one 

of the following positions: 

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PARK (Automatic)  

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NEUTRAL (Manual)  

7. Start the engine and allow to idle.  

8. Operate the A/C system for 5 minutes.  

9. Inspect for the following: 

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Abnormal frost areas  

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Unusual noises  

10. Record the following information: 

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The outlet air temperatures  

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The low-side pressure  

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The high-side pressure  

11. Compare the low and high side 

pressures and the output temperatures to 
the table below.  

Does all the data recorded fall within the 
specified ranges of the table below?

IMPORTANT:

When using the print function of the J 
43600 for this step, press the RESET 
button first. In order to capture the 
correct information, wait 5 minutes 
after pressing the RESET button, 
before pressing the PRINT button. See 
Special Tools and Equipment .

-

Go to Step 8

Go to Step 3

If the pressures and temperatures recorded do 
not fall within the specified ranges: 

1. Continue to operate the A/C system for 

an additional 5 minutes.  

 

2004 Hummer H2 

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2

  

3

2. Record the pressures and temperatures 

again.  

3. Compare the low and high side 

pressures and the output temperature to 
the table below.  

 
Does all the data recorded fall within the 
specified ranges of the table below?

-

Go to Step 8

Go to Step 4

4

Do the high and low side pressures fall within 
the specified ranges but the outlet temperatures 
do not?

-

Go to Air 

Conditioning 

(A/C) 

Diagnostics - 

Pressure Zone A

Go to Step 5

5

Is the low side pressure higher than the 
specified range and the high side pressure 
within or lower than the specified range?

-

Go to Air 

Conditioning 

(A/C) 

Diagnostics - 

Pressure Zone B

Go to Step 6

6

Are the low and high side pressures both 
higher than the specified ranges?

-

Go to Air 

Conditioning 

(A/C) 

Diagnostics - 

Pressure Zone C

Go to Step 7

7

Is the low side pressure within or lower than 
the specified range and the high side pressure 
higher than the specified range?

-

Go to Air 

Conditioning 

(A/C) 

Diagnostics - 

Pressure Zone D

Go to Step 8

8

Operate the system in order to verify the test 
results. 
Did you find the same results?

-

System OK

Go to 

Symptoms - 

HVAC Systems 

- Automatic in 

HVAC Systems 

- Automatic

 

2004 Hummer H2 

2004 HVAC Heating, Ventilation and Air Conditioning - Hummer H2