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A/C System Performance Test

WARNING: This page is about a different car, the 2002 Pontiac Firebird and 2002 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Tools Required: ACR 2000 Air Conditioning Service Center (J-43600).
NOTE: This test measures the operating efficiency of the A/C system under the following conditions:
  • The Current Ambient Air Temperature
  • The Current Relative Humidity
  • The High Side Pressure Of The A/C System
  • The Pressure At The Low-Pressure Side Of The Refrigeration System
  • The Temperature Of The Air Being Discharged Into The Passenger Compartment
NOTE: The ambient air temperature must be at least 60°F (16°C). 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. Park the vehicle inside or in the shade. Open the windows in order to ventilate the interior of the vehicle. If the A/C system was operating, allow the A/C system to equalize. Allow about 2 minutes. Ensure that the ignition key is in the OFF position. Install the ACR 2000 Air Conditioning Service Center. Record the ambient air temperature displayed on the ACR 2000 Air Conditioning Service Center. Record readings of the low and high side static pressures. Are both the low and high side pressures within the specified value?
    • Above 60°F (16°C) - 50 psi (345 kPa)
    • Above 75°F (24°C) - 70 psi (483 kPa)
    • Above 90°F (33°C) - 100 psi (690 kPa)
    If so, go to next step. If not, leak test system. See LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.
    2. NOTE: Record the relative humidity and the ambient air temperature at the time of the test.
  2. Close the vehicle doors and windows. Open the driver door window 5-6" (12.7-15.2 cm). Set the HVAC control to the following positions:
    • Max A/C The Blower Control To The Highest Position
    • The HVAC Control Assembly To Discharge Air Through The A/C Outlets
    • The Temperature Control To The Coldest Position
    • All A/C Outlets Open
    • Install Temperature To The ACR 2000 Air Conditioning Service Center In The Left And Right Center A/C Air Outlets
    Apply the parking brake. Place the transmission in Park on vehicles with automatic transmissions, and Neutral on vehicles with manual transmissions. Start the engine and allow to idle. Operate the A/C system for 5 minutes. Inspect for the following:
    • Abnormal Frost Areas
    • Unusual Noises
    In order to capture the correct information, press the reset button of the J-43600 before pressing the print button after the 5 minute operating time. Record the following information:
    • The Outlet Air Temperatures
    • The Low-Side Pressure
    • The High-Side Pressure
    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? If so, go to step  4. If not, go to next step.
  3. If the pressures and temperatures recorded do not fall within the specified ranges, continue to operate the A/C system for an additional 5 minutes. Record the pressures and temperatures again. Compare the low and high side pressures and the output temperature to the table below. See Fig 1. Does all the data recorded fall within the specified ranges of the table below? If so, go to step  8. If not, go to next step.
  4. Do the high and low side pressures fall within the specified ranges but the outlet temperatures do not? If so, go to A/C PRESSURE ZONE "A" DIAGNOSIS  under SYSTEM TESTS. If not, go to next step.
  5. Is the low side pressure higher than the specified range and the high side pressure within or lower than the specified range? If so, go to A/C PRESSURE ZONE "B" DIAGNOSIS  under SYSTEM TESTS. If not, go to next step.
  6. Are the low and high side pressures both higher than the specified ranges? If so, go to A/C PRESSURE ZONE "B" DIAGNOSIS  under SYSTEM TESTS. If not, go to next step.
  7. Is the low side pressure within or lower than the specified range and the high side pressure higher than the specified range? If so, go to A/C PRESSURE ZONE "D" DIAGNOSIS  under SYSTEM TESTS. If not, go to next step.
  8. Operate the system in order to verify the test results. Did you find the same results? If so, system is okay. If not, go to SYMPTOM DIAGNOSIS  in TROUBLE SHOOTING
Fig 1: A/C Performance Table
G00189691Courtesy of GENERAL MOTORS CORP.
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