Compressor Controls

COMPRESSOR CONTROLS

The compressor for the air conditioning system is driven by the engine by means of a belt drive and the A/C Compressor Clutch. The clutch allows the compressor to be disengaged when air conditioning is not required. Power to the A/C Compressor Clutch is supplied by the HTR-A/C Fuse.

The A/C Compressor Clutch Diode is connected across the terminals of the A/C Compressor Clutch. Whenever the clutch is de-energized, the magnetic field around R collapses, generating an induced voltage in the clutch coil. The Diode provides a path for the voltage resulting from the induced voltage so other circuit components are not damaged.


With the A/C-Heater Selector Switch in any mode except VENT or HEAT, voltage flows from the LT GRN (66) wire through the Low Pressure Switch and the DK GRN/WHT (459) wire to the A/C Control Relay and the Electronic Control Module (ECM).

The A/C Request signal to the ECM closes the A/C Cutout Switch in the ECM providing a ground through the DK BLU (458) wire at the A/C Control Relay. This allows voltage to flow from the IGN/GAU Fuse to the A/C Control Relay, energizing the relay. Voltage from the HTR-A/C Fuse then flows through the closed contacts of the relay to energize the A/C Compressor Clutch.

The A/C Request signal to the ECM also increases engine idle speed.