A/C Signal: Description and Operation

To improve idle quality and wide open throttle (WOT) performance, the A/C compressor is controlled by the ECM. The system consists of a dual pressure switch, an EVAP thermo switch, 3 control relays and the compressor. The A/C relays are ECM controlled so that the ECM can increase idle speed before turning "ON" the compressor clutch and turn the clutch "OFF" during WOT. The ECM also disengages the compressor clutch when high power steering pressure is present or if the engine is overheating.