B250 3/4 Ton Van V8-318 5.2L VIN T FI (1992)
Compressor Clutch Relay: Description and Operation
Relay Locations
PURPOSE
Supplies ground path for A/C clutch.
OPERATION
Controlled by A/C or defrost switch (inside vehicle) and engine controller. Relay receives battery voltage from radiator fan relay, (A/C clutch relay
will not energize unless the radiator fan relay is energized).
When A/C or defrost is selected, (turned ON), inside vehicle, and low and high pressure switches are closed, engine controller receives an A/C ON
signal. Engine controller then supplies relay ground (energizing the relay).
If engine controller senses Wide Open Throttle (WOT) or low idle speed condition, it removes relay ground (de-energizing the relay),
discontinuing A/C clutch engagement.
The engine controller will also de-energize the relay if engine coolant temperature excedes 257° F.
