Diagnosis

DTC P0530, P0560, P1639, or P1641 can affect A/C operation. Refer to the DTC tables if any DTCs are set.

The PCM Controlled A/C Circuit Diagnosis table should be used for diagnosing the electrical portion of the A/C compressor clutch circuit if a DTC is not set. To diagnose the refrigerant portion of the HVAC system, refer to A Diagnostic Starting Point in Heating and Air Conditioning. A scan tool will be used in diagnosing the system. The scan tool has the ability to display the A/C request and refrigerant pressure inputs to the PCM. The scan tool can display when the PCM has commanded the A/C clutch ON. The scan tool also has the ability to override the A/C request signal and energize the A/C control relay.