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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> HVAC Systems - Manual >> Performance Tests >> A/C Performance Test >> Test Procedure

Test Procedure

  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 for about 2 minutes. Turn the ignition OFF. Install the ACR 2000 Air Conditioning Service Center. Record the ambient air temperature displayed on the ACR 2000 Air Conditioning Service Center. Record the low and high side STATIC pressure readings. Are both the low side and high side pressures within the specified value?
    • At 60°F (16°C) More Than 50 Psi (345 kPa)
    • At 75°F (24°C) More Than 70 Psi (483 kPa)
    • At 90°F (33°C) More Than 100 Psi (690 kPa)
    If so, go to next step. If not, refrigerant level is low or empty. 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 drivers door window 5-6" (12.7-15.2 cm). Select the following HVAC control settings:
    • A/C Is On
    • Blower Speed Is At Maximum
    • Vent Mode Position
    • Coldest Temperature Setting
    • All A/C Outlets Are Open
    Install the temperature probes of 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 (Automatic) or Neutral (Manual). Start the engine. Operate the A/C system for 5 minutes. Inspect A/C components for abnormal frost areas or unusual noises. Press the RESET button, before using the print function of the ACR 2000 Air Conditioning Service Center. Print 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. See Fig 2. Does all the data recorded fall within the specified ranges of the table? If so, go to step  4. If not, go to next step.
  3. If the pressures and temperature recorded do not fall within the specified ranges, continue to operate the A/C system for an additional 5 minutes and reset the ACR 2000 Air Conditioning Service Center and record the pressures and temperature again. Compare the low and high side pressures and the output temperature to the table. See Fig 2. Does all the data recorded fall within the specified ranges of the 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 greater than the specified range, but the high side pressure within or less 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 greater 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 high side pressure greater than the specified range, but the low side pressure is within or less 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, go to SYMPTOM DIAGNOSIS  under TROUBLE SHOOTING.
Fig 1: A/C Pressure Zone Classification Chart (Blazer - Jimmy Canadian, Sonoma & S10 Pickup)
G00177726Courtesy of GENERAL MOTORS CORP.
Fig 2: A/C Performance Test Table (Blazer - Jimmy Canadian), Sonoma & S10 Pickup)
G00177725Courtesy of GENERAL MOTORS CORP.
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