Lumina L4-151 2.5L (1991)
Compressor Clutch Relay: Description and Operation
Wiring Diagram For A/C Clutch Control
The ECM controls the A/C compressor clutch relay. When the A/C is turned on, the ECM delays the clutch engagement to allow the IAC valve to raise
the engine idle speed to compensate for the added load. The ECM allows the relay to disengage the A/C clutch at wide open throttle.