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A/C System Performance Test

WARNING: This page is about a different car, the 2002 Pontiac Sunfire and 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Tools required: ACR 2000 Air Conditioning Test Center (J-43600).
NOTE: Ambient air temperature must be at least 60°F (16°C). Do Not induce additional air flow across front of vehicle during this 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 (about 2 minutes). Ensure that the ignition is in the OFF position. Install the ACR 2000 Air Conditioning Test Center. Record the ambient air temperature displayed on the ACR 2000 Air Conditioning Test 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, system may be low on refrigerant. 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 inches. Set the HVAC control to the following positions:
    • The A/C on 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 probe from ACR 2000 Air Conditioning Test Center in the left and right center A/C air outlets.
    • Apply the parking brake.
    Place the gearshift lever in Park for Automatic transaxles, and Neutral for Manual transaxles. Start the engine and allow to idle. Operate the A/C system for 5 minutes. Inspect for abnormal frost areas and unusual noises. When using the print function of the ACR 2000 Air Conditioning Test Center for this step it is necessary to press the reset button before pressing the print button after the 5 minute operating time in order to capture the correct information. Record the following information: The outlet air temperatures, the low-side pressure and the high-side pressure. Compare the low and high side pressures and the output temperatures to the table. See Fig 1 and Fig 2 . Does all the data recorded fall within the specified ranges of the A/C Performance Table? 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 of the A/C Performance Table, 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 A/C Performance Table. See Fig 1 and Fig 2 . Does all the data recorded fall within the specified ranges of the A/C Performance Table? 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 "C" 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, see SYMPTOM DIAGNOSIS  under TROUBLE SHOOTING.
Fig 1: A/C Performance Table
G00189634Courtesy of GENERAL MOTORS CORP.
Fig 2: A/C Performance Chart
G00189635Courtesy of GENERAL MOTORS CORP.
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