Chart C-10, A/C Compressor Clutch Circuit Diagnosis (1 Of 2): Notes

A/C compressor clutch relay is controlled by the Powertrain Control Module (PCM). The PCM provides a ground on circuit No. 459 and A/C is requested. PCM will delay A/C compressor clutch engagement momentarily after A/C is requested. This delay allows Idle Air Control (IAC) valve to adjust engine RPM for additional load.

PCM will temporarily disengage A/C compressor clutch for a precalibrated time during one or more of the following conditions: engine not running, engine coolant temperature greater than 255°F (124°C), A/C refrigerant pressure less than -17 psi (-1.2 kg/cm² ) or greater than 457 psi (32 kg/cm² ) and IAC reset. A/C compressor clutch will remain disengaged if Diagnostic Trouble Code (DTC) P1530 is present, and no A/C request signal exists from A/C select switch or circuit.

1. If DTCs are present, diagnose DTCs first. See appropriate TESTS W/CODES - 3.1L article in the ENGINE PERFORMANCE section. PCM will energize A/C compressor clutch relay only when engine is running. This test will determine whether relay or circuit No. 459 is faulty.
2. Determines if signal is reaching PCM through circuit No. 66 from A/C control panel. Signal should only be present when A/C mode or defrost mode is selected.