A/C Signal: Description and Operation

PURPOSE

Powertrain Control Module (PCM) monitors engine load and A/C system pressure, and cycles the A/C compressor clutch accordingly.

OPERATION

When the A/C or defrost switch is ON, and the A/C high and low pressure switches are closed, the PCM receives an "A/C SELECTED SIGNAL".

- PCM engages A/C compressor clutch (by grounding clutch relay).

- PCM cycles compressor clutch depending on engine load and A/C system pressure.

- PCM maintains correct engine idle speed, through the Idle Air Control (IAC) Motor.