Compressor Controls

CIRCUIT OPERATION
Compressor Relay
The A/C Compressor Control Relay opens and closes the circuit to the A/C Compressor Clutch. The coil of the relay is grounded through the Electronic Control Module (ECM). This enables the ECM to control the compressor and turn off the air conditioning to reduce the load on the engine when necessary. The ECM also receives an air conditioner "On" signal in the form of Battery voltage from the A/C Compressor Control Relay. This signals that the system has been turned on at the A/C Control Head and that the cycling switch is closed, calling for more cooling.

Compressor Clutch Diode
A diode is connected across the A/C Compressor Clutch. It suppresses the high voltage spikes that are generated by the collapsing magnetic field of the clutch coil. These spikes occur when the clutch is turned off.