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Test Description

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

This test measures the operating efficiency of the A/C system under the following conditions:

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 (AATs).
Step Action Values Yes No
IMPORTANT:
  • The ambient air temperature (AAT) 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 (AAT) displayed on the J 43600  . See Special Tools .
  7. Record readings of the low and high side STATIC pressures.
Are both the low and high side pressures within the specified value?		 Above 16°C (60°F) - 345 kPa (50 psi)
Above 24°C (75°F) - 483 kPa (70 psi)
Above 33°C (90°F) - 690 kPa (100 psi)		 Go to Step 2  Go to Leak Testing 
2 
    IMPORTANT: Record the relative humidity and the AAT AT THE TIME OF THE TEST.
  1. Close the vehicle doors and windows.
  2. Open the driver door window 12.7-15.2 cm (5-6 in).
  3. Select the following HVAC control setting:
    • The A/C is ON.
    • The coldest temperature setting
    • The maximum blower speed
    • Recirculation mode
    • The instrument panel (I/P) outlet mode
    • All I/P outlets are OPEN
  4. Install the temperature probes of the J 43600  in the left and right center panel air outlets. See Special Tools .
  5. Apply the parking brake.
  6. Place the transmission in PARK.
  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: When performing this step it is necessary to press the RESET button on the J 43600  before pressing the PRINT button. 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 A/C performance table below.
Does all the data recorded fall within the specified ranges of the A/C performance table?		 - 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. Record the pressures and temperatures again.
  3. Compare the low and high side pressures and the panel output temperature to the A/C performance table.

Does all the data recorded fall within the specified ranges of the A/C performance table?		 - 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 is 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
Fig 1: Illustrating A/C System Pressure - Zone Classification
GM1602588Courtesy of GENERAL MOTORS CORP.
A/C Performance Table

Ambient Air Temperature Relative Humidity Service Port Pressure Maximum Left Center Discharge Air Temperature
Low Side High Side
13-18°C (55-65°F) 0-100% 151-234 kPa (22-34 psi) 558-909 kPa (81-132 psi) 12°C (52°F)
19-24°C (66-75°F) Below 40% 151-234 kPa (22-34 psi) 730-1109 kPa (106-161 psi) 9°C (48°F)
Above 40% 151-275 kPa (22-40 psi) 771-1150 kPa (112-167 psi) 14°C (57°F)
25-29°C (76-85°F) Below 35% 165-268 kPa (24-39 psi) 1012-1322 kPa (147-192 psi) 13°C (54°F)
35-50% 186-282 kPa (27-41 psi) 1019-1329 kPa (148-193 psi) 13°C (55°F)
Above 50% 206-310 kPa (30-45 psi) 1040-1336 kPa (151-194 psi) 17°C (61°F)
30-35°C (86-95°F) Below 30% 206-303 kPa (30-44 psi) 1233-1577 kPa (179-229 psi) 15°C (59°F)
30-50% 220-323 kPa (32-47 psi) 1240-1577 kPa (180-229 psi) 18°C (63°F)
Above 50% 241-344 kPa (35-50 psi) 1247-1577 kPa (181-229 psi) 19°C (66°F)
36-41°C (96-105°F) Below 20% 248-344 kPa (36-50 psi) 1502-1839 kPa (218-267 psi) 18°C (64°F)
20-40% 254-358 kPa (37-52 psi) 1502-1839 kPa (218-267 psi) 19°C (66°F)
Above 40% 275-372 kPa (40-54 psi) 1502-1832 kPa (218-266 psi) 22°C (70°F)
42-46°C (106-115°F) Below 20% 296-385 kPa (43-56 psi) 1770-2060 kPa (257-299 psi) 22°C (70°F)
Above 20% 303-392 kPa (44-57 psi) 1756-2053 kPa (255-298 psi) 23°C (72°F)
47-49°C (116-120°F) Below 30% 344-427 kPa (50-62 psi) 1977-2280 kPa (287-331 psi) 25°C (77°F)
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