A/C Request Signal

OPERATION
When the heater and A/C control is placed in the A/C Mode, a request signal is sent to the Powertrain Control Module (PCM). The PCM will then energize the A/C clutch relay, unless abnormally high or low A/C pressure is detected by the A/C refrigerant pressure sensor. The PCM will also turn the cooling fans "ON" when A/C is requested. The A/C clutch relay is controlled by the PCM so that the PCM can increase idle speed before turning "ON" the clutch or disable the clutch during Wide Open Throttle (WOT), and high coolant temperature.

This system consists of a heater and A/C control, A/C pressure cycling switch, an A/C refrigerant pressure sensor, an A/C clutch relay, the compressor clutch, and the PCM.
The A/C refrigerant pressure cycling switch is closed when there is sufficient system pressure (depending on refrigerant charge (R134a) and ambient temperature).