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Test K: Compressor Clutch Does Not Engage

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  1. Perform SYSTEM OPERATION CHECK  under TROUBLE SHOOTING. Go to next step.
    2. NOTE: The A/C compressor relay output is disabled if engine coolant temperature is above 250°F (121°C). The engine coolant indicator will illuminate at this temperature.
  2. Start the engine. Observe the coolant temperature indicator. Is the engine coolant temperature indicator illuminated? If so, check engine for overheating conditions. If not, go to next step.
    3. NOTE: For A/C compressor operation, the ambient air temperature must be above 38°F (3°C).
  3. Start the engine. Place the blower motor switch in the maximum speed position. Place the A/C request switch in the ON position. Place the air temperature switch in the coldest position. Does the A/C compressor operate? If so, check for intermittent and poor connections. If not, go to next step.
  4. Park the vehicle inside or not in direct sunlight. Open a window in order to ventilate the interior of the vehicle. If the A/C system was operating, then wait for approximately 2 minutes. Turn ignition off. Install ACR 2000 Air Conditioning Service Center. Record the ambient temperature at the vehicle. Record readings of the low and high side static pressures. Compare the pressure values with the specifications for the ambient air temperature. See A/C SYSTEM PERFORMANCE TEST  under PERFORMANCE TESTS. Are the pressure values within the specifications for the ambient air temperature, and within 15 psi (103 kPa) of each other? If so, go to next step. If not, see LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.
    5. NOTE: The HVAC control assembly is inoperative when the module does not respond to an operator control request.
  5. Is the HVAC control assembly inoperative? If so, go to step  20. If not, go to next step.
  6. Start the engine. With a scan tool, observe the A/C RELAY COMMAND parameter in the Powertrain Data List. Place the A/C request switch in the ON position. Does the scan tool indicate that the A/C RELAY COMMAND parameter is on? If so, go to step  9. If not, go to next step.
  7. Does the A/C request indicator illuminate? If so, go to next step. If not, go to step  22.
    8. NOTE: If the fused jumper opens during this step the A/C request signal circuit is short to voltage.
    NOTE: Ensure that the blower motor switch is not in the OFF position during this step.
  8. Turn ignition off. Disconnect the A/C high pressure switch. Connect a 3-ampere fused jumper between the A/C request circuits at the A/C high pressure switch connector. Start the engine. With a scan tool, observe the A/C RELAY COMMAND parameter. Place the A/C request switch in the ON position. Does the scan tool indicate that the A/C RELAY COMMAND parameter is ON? If so, go to step  33. If not, go to step  27.
  9. With a scan tool, observe the A/C COMPRESSOR CYCLING SWITCH parameter in the Engine Data 2 data list. Does the scan tool indicate the A/C COMPRESSOR CYCLING SWITCH parameter is NORMAL? If so, go to step  11. If not, go to next step.
    10. NOTE: If the fused jumper opens during this step the A/C pressure sensor signal is short to voltage.
  10. Turn ignition off. Disconnect the A/C low pressure switch. Connect a 3-ampere fused jumper between the low A/C low pressure switch signal and ground circuit. Start the engine. With a scan tool, observe the A/C COMPRESSOR CYCLING SWITCH parameter. Does the scan tool indicate the A/C COMPRESSOR CYCLING SWITCH parameter is NORMAL? If so, go to step  30. If not, go to step  23.
  11. With a scan tool, command the A/C COMPRESSOR CLUTCH RELAY ON and OFF. Does the A/C COMPRESSOR CLUTCH RELAY turn ON and OFF with each command? If so, go to step  17. If not, go to next step.
  12. Turn ignition off. Disconnect the A/C compressor clutch relay. Turn ignition on. Probe the coil side voltage supply circuit of the A/C compressor clutch relay with a test light that is connected to ground. Does the test light illuminate? If so, go to next step. If not, go to step  28.
  13. Connect a test light between the control circuit and the coil side voltage supply circuit of the A/C compressor clutch relay. With a scan tool, command the A/C compressor clutch relay ON and OFF. Does the test light turn ON and OFF with each command? If so, go to step  29. If not, go to next step.
  14. Does the test light remain illuminated with each command? If so, go to step  16. If not, go to next step.
  15. Check the A/C compressor clutch relay control circuit for an open. Did you find and correct the condition? If so, go to step  41. If not, go to step  34.
  16. Check the control circuit of the A/C compressor clutch relay for a short to ground. Did you find and correct the condition? If so, go to step  41. If not, go to step  34.
  17. Turn ignition off. Disconnect the A/C compressor clutch relay. Probe the switch side voltage supply circuit of the A/C compressor clutch relay with a test light that is connected to ground. Does the test light illuminate? If so, go to next step. If not, go to step  19.
    18. NOTE: If the fused jumper opens during this step the A/C compressor clutch supply voltage circuit is shorted to ground.
  18. Connect a 10-ampere fused jumper between the switch side voltage circuit of the A/C compressor clutch relay and the supply voltage circuit of the A/C compressor clutch. Turn ignition on. Does the A/C compressor clutch engage? If so, go to step  29. If not, go to step  25.
  19. Repair the A/C compressor clutch relay switch side voltage supply circuit. After repairs are complete, go to step  41.
  20. Check the HVAC control assembly ignition 3 voltage circuit for a short to ground, for a high resistance, or for an open. Did you find and correct the condition? If so, go to step  41. If not, go to next step.
  21. Check the HVAC control assembly ground circuit for an open. Did you find and correct the condition? If so, go to step  41. If not, go to step  32.
    22. NOTE: When the blower motor is in the OFF position, a voltage is applied to the OFF blower motor control circuit. The A/C system will not operate if a voltage is applied to the OFF blower motor control circuit.
    NOTE: Ensure that the blower motor switch is not in the OFF position during this step.
  22. Check the off blower motor control circuit for a short to voltage. Did you find and correct the condition? If so, go to step  41. If not, go to step  32.
  23. Check the A/C low pressure switch signal circuit for a high resistance or for an open. Did you find and correct the condition? If so, go to step  41. If not, go to next step.
  24. Check the A/C low pressure switch ground circuit for a high resistance or for an open. Did you find and correct the condition? If so, go to step  41. If not, go to step  34.
  25. Check the A/C compressor clutch supply voltage circuit for a short to ground, for a high resistance, or for an open. Did you find and correct the condition? If so, go to step  41. If not, go to next step.
  26. Check the A/C compressor clutch ground circuit for a high resistance or for an open. Did you find and correct the condition? If so, go to step  41. If not, go to step  31.
  27. Turn ignition off. Reconnect the A/C high pressure switch. Check the A/C request signal circuit for a short to ground, for a high resistance, or for an open. Did you find and correct the condition? If so, go to step  41. If not, go to step  34.
  28. Repair the coil side voltage supply circuit of the A/C compressor clutch relay. After repairs are complete, go to step  41.
  29. Inspect A/C compressor clutch relay for poor connections. Did you find and correct the condition? If so, go to step  41. If not, go to step  35.
  30. Inspect A/C low pressure switch harness connector for poor connections. Did you find and correct the condition? If so, go to step  41. If not, go to step  36.
  31. Inspect the A/C compressor clutch harness connector for poor connections. Did you find and correct the condition? If so, go to step  41. If not, go to step  38.
  32. Inspect the HVAC control assembly harness connector for poor connections. Did you find and correct the condition? If so, go to step  41. If not, go to step  39.
  33. Inspect A/C high pressure switch harness connector for poor connections. Did you find and correct the condition? If so, go to step  41. If not, go to step  37.
  34. Inspect Powertrain Control Module (PCM) harness connector for poor connections. Did you find and correct the condition? If so, go to step  41. If not, go to step  40.
  35. Replace the A/C compressor clutch relay. See COMPRESSOR RELAY  under REMOVAL & INSTALLATION. After repairs are complete, go to step  41.
  36. Replace the A/C low pressure switch. See A/C LOW PRESSURE SWITCH  under REMOVAL & INSTALLATION. After repairs are complete, go to step  41.
  37. Replace the A/C high pressure switch. See A/C HIGH PRESSURE SWITCH  under REMOVAL & INSTALLATION. After repairs are complete, go to step  41.
  38. Replace the A/C compressor clutch coil. See COMPRESSOR SERVICING article in GENERAL SERVICING. After repairs are complete, go to step  41.
    39. NOTE: Perform the calibration procedure for the HVAC control assembly.
  39. Replace the HVAC control assembly. See HVAC CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. After repairs are complete, go to step  41.
  40. Replace the PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. Program the PCM. After repairs are complete, go to next step.
  41. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to step  4.
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