Diesel Data: Automotive Repair

A/C Signal: Description and Operation

CONDITIONS

A/C or defrost switch is turned ON.

A/C low pressure, and high pressure switches are closed.

OPERATION

^ Powertrain Control Module (PCM) receives an A/C selected signal.

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

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

^ PCM monitors status of switches and cycles compressor clutch accordingly.