Compressor Controls

PURPOSE
In order to improve idle quality and Wide Open Throttle (WOT) performance, A/C compressor operation is controlled by the Powertrain Control Module (PCM).

OPERATION
This system consists of a pressure cycling switch, a high pressure cut-out switch, a control relay, the compressor clutch, the PCM, and the HVAC control head.

The pressure cycling switch is closed when there is sufficient system pressure (depending on refrigerant charge and ambient temperature). When both the high pressure switch and the pressure cycling switch are closed, a complete circuit will exist between the HVAC control head and PCM.

12 volts will be applied at the PCM by the HVAC control head when an A/C mode is selected and refrigerant pressure is sufficient to close the pressure cycling switch. The PCM will then energize the A/C clutch control relay. The PCM will also turn the left cooling fan (Fan 1) ON when A/C is requested.