Compressor Clutch Relay: Description and Operation

A/C Control Relay:

A/C COMPRESSOR CONTROL RELAY
The A/C control relay is designed to disengage the A/C compressor clutch during full throttle acceleration and momentarily during engine start-up on a warm motor. The relay is ECM controlled. Voltage is supplied from the A/C power feed circuit and the ECM completes the ground to open a set of normally closed points. This turns the compressor clutch OFF.

The ECM completes the ground circuit and de-energizes the compressor when a high TPS voltage (wide open throttle) is sensed or an engine run signal is sensed with coolant temperature above 120°C (250°F).

On a warm engine start-up, a time delay of about 3 seconds allows the engine speed to stabilize before the compressor engages.