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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 186 (Heating, Ventilation, And Air Conditioning) >> Diagnostic Information and Procedures >> Air Conditioning (A/C) System Performance Test (Short Wheel Base) >> Test Description

Test Description

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

  1. 1:  This step determines if the A/C system has at least the minimum refrigerant charge required to operate the system without damage.
  2. 2:  This step measures the performance of the A/C system.
  3. 3:  This step is to allow for vehicle variations as well as high ambient air temperatures.
Step Action Values Yes No
IMPORTANT:
  • The ambient air temperature must be at least 16°C (60°F).
  • Do not induce additional air flow across the front of the vehicle during the test.
  • 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 for about 2 minutes.
  4. Turn OFF the ignition.
  5. Install the J 43600  ACR 2000 Air Conditioning Service Center. See Special Tools .
  6. Record the ambient air temperature displayed on the J 43600  . See Special Tools .
  7. Record the low and high side STATIC pressure readings.
Are both the low and high side pressures within the specified value?
  • Greater than 16°C (60°F), 345 kPa (50 psi)
  • Greater than 24°C (75°F), 483 kPa (70 psi)
  • Greater than 33°C (90°F), 690 kPa (100 psi)
 Go to Step 2  Go to Leak Testing (Non-HP2)  or Leak Testing (HP2) 
2 
    IMPORTANT: Record the relative humidity and the ambient air temperature at the time of the test.
  1. Close the vehicle doors and windows.
  2. Open the drivers door window 127-152 mm (5-6 in).
  3. Select the following HVAC control settings:
    • The A/C ON.
    • The coldest temperature setting
    • The maximum blower speed
    • The I/P panel outlet mode
    • All I/P panel outlets are OPEN
    • Recirculation mode
  4. Install the temperature probes to the J 43600  in the left and right center A/C air outlets. See Special Tools .
  5. Apply the parking brake.
  6. Place the transaxle/transmission in one of the following positions:
    • PARK for Automatic
    • NEUTRAL for Manual
  7. Start the engine.
  8. Operate the A/C system for 5 minutes.
  9. Inspect A/C components for the following conditions:
    • Abnormal frost areas
    • Unusual noises
    10. IMPORTANT: Press the RESET button, before using the print function of the J 43600  . See Special Tools .
  10. Print the following information:
    • The panel outlet air temperatures
    • The low-side pressure
    • The high-side pressure
  11. Compare the low and high side pressures and the panel output temperatures 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 3 
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.
  2. RESET the J 43600  and record the pressures and temperatures again. See Special Tools .
  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 panel outlet temperatures do not? - Go to Air Conditioning (A/C) Diagnostics - Pressure Zone A  Go to Step 5 
5 Is the low side pressure greater than the specified range but the high side pressure within or less 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 greater than the specified ranges? - Go to Air Conditioning (A/C) Diagnostics - Pressure Zone C  Go to Step 7 
7 Is the high side pressure greater than the specified range, but the low side pressure is within or less 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 - Manual
or
Symptoms - HVAC Systems - Automatic
Fig 1: A/C System Pressure - Zone Classification with Aux A/C
GM1747476Courtesy of GENERAL MOTORS CORP.
A/C Performance Table with Aux A/C

Ambient Air Temperature Relative Humidity Service Port Pressure Maximum Discharge Air Temperature
Low Side High Side Left Front Center Left Rear
13-18°C (55-65°F) 0-100% 151-220 kPa (22-32 psi) 537-937 kPa (78-136 psi) 5°C (41°F) 7°C (45°F)
19-24°C (66-75°F) Below 40% 151-248 kPa (22-36 psi) 689-1109 kPa (100-161 psi) 8°C (46°F) 10°C (50°F)
Above 40% 151-282 kPa (22-41 psi) 757-1178 kPa (110-171 psi) 10°C (50°F) 12°C (54°F)
25-29°C (76-85°F) Below 35% 186-289 kPa (27-42 psi) 978-1322 kPa (142-192 psi) 11°C (52°F) 13°C (55°F)
35-50% 206-303 kPa (30-44 psi) 1019-1336 kPa (148-194 psi) 12°C 54°F) 14°C (57°F)
Above 50% 213-323 kPa (31-47 psi) 1040-1378 kPa (151-200 psi) 14°C (57°F) 16°C (61°F)
30-35°C (86-95°F) Below 30% 234-337 kPa (34-49 psi) 1212-1577 kPa (176-229 psi) 15°C (59°F) 18°C (64°F)
30-50% 248-351 kPa (36-51 psi) 1233-1598 kPa (179-232 psi) 17°C (63°F) 19°C (66°F)
Above 50% 261-372 kPa (38-54 psi) 1260-1619 kPa (183-235 psi) 19°C (66°F) 21°C (70°F)
36-41°C (96-105°F) Below 20% 289-385 kPa (42-56 psi) 1488-1853 kPa (216-269 psi) 19°C (66°F) 21°C (70°F)
20-40% 296-399 kPa (43-58 psi) 1488-1853 kPa (216-269 psi) 21°C (70°F) 23°C (73°F)
Above 40% 310-413 kPa (45-60 psi) 1508-1853 kPa (219-269 psi) 22°C (72°F) 24°C (75°F)
42-46°C (106-115°F) Below 20% 344-434 kPa (50-63 psi) 1770-2080 kPa (257-302 psi) 23°C (73°F) 25°C (77°F)
Above 20% 351-447 kPa (51-65 psi) 1770-2067 kPa (257-300 psi) 24°C (75°F) 27°C (81°F)
47-49°C (116-120°F) Below 30% 392-482 kPa (57-70 psi) 1998-2301 kPa (290-334 psi) 27°C (81°F) 28°C (82°F)
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