GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2000 🢒 S/T Isuzu - 2WD 🢒 HVAC 🢒 Heating, Ventilation and Air Conditioning 🢒 System Performance Test

Perform the following test if you suspect a malfunction in the refrigerant system due to abnormal system pressures.

Tools Required

J 21213-A Four Jack Dual Range Temperature Tester or an equivalent

  1. Park the vehicle inside, or in a shaded area.
  2. Open the doors or the windows of the vehicle.
  3. Vent the engine exhaust if necessary.
  4. Open the hood.
  5. Install the high and low side pressure gauges.

    6. Route the lines over the rear hood seal. Tape the gauges to the windshield in order to view the gauges.

  6. Close the hood to the safety latch position.
  7. Record the ambient temperature at the vehicle.

    8. Important: Ensure that you record the relative humidity and the ambient temperature conditions at the time of the test.

  8. Record the relative humidity.

    9. Use a psychrometer or consult the local weather bureau.

  9. Close the doors or the windows of the vehicle.
  10. Set the mode control to MAX A/C.
  11. Adjust the blower speed to HI.
  12. Adjust the temperature to full COLD.
  13. Open the air conditioning outlets.
  14. Install J 21213-A or an equivalent into the right center air conditioning outlet.
  15. Place the transmission in PARK or NEUTRAL.
  16. Start the engine.
  17. Stabilize the engine speed at 1500 RPM.

    18. Start the timer.

  18. Run the air conditioning system until the outlet air reaches the lowest temperature (about 3 minutes).
  19. Record the following statistics:
    20. • The outlet air temperature
    • The high-side pressure
    • The low side-pressure
  20. Turn off the engine.
  21. Compare the readings. Normal operating air conditioning systems should not exceed normal levels. Refer to the following diagnostic aids:
    22. • Pressure Temperature Relationship of R-134a
    • System Performance Test With 1,500 RPM Engine Speed
  22. Inspect the outer surfaces of the radiator and the condenser cores.

    23. Inspect between the condenser and the radiator as well as the outer surfaces. Ensure that the airflow is not blocked by the following materials:

    • Dirt
    • Leaves
    • Other foreign matter
  23. Inspect the following components for restrictions or kinks:
    24. • The evaporator core
    • The condenser core
    • The hoses
    • The tubes
  24. Inspect for refrigerant leaks.
  25. Inspect all of the air ducts for leaks or restrictions.

    26. Low air flow may indicate a restricted evaporator core.

  26. Inspect the compressor clutch for slippage.
  27. Inspect the drive belt for improper tension.

If you do not find a problem in the CCOT system, refer to the following procedure: CCOT Air Conditioning (A/C) System Diagnosis .