Radiator Cooling Fan Motor Relay: Description and Operation

Cooling Fan Wiring Diagram:

Purpose:
All front wheel drive vehicles with transversely mounted engines, and other vehicles, use electric cooling fans. The fans are used for engine and A/C condenser cooling but only operate under certain conditions.

Operation:
The engine coolant fan is controlled by the ECM via the coolant fan relay. A calibrated set of criteria programmed into the ECM will energize the fan relay. The following conditions control the fan:

^ Engine coolant temperature (ECT) sensor signal indicating 109°C (228°F) or greater will turn the fan "ON"

^ Engine coolant temperature (ECT) sensor signal indicating 98°C or less will turn the fan "OFF"

^ The fan will turn "ON" if A/C is requested and vehicle speed is less than 56 km/h (35 mph)

^ If vehicle speed is greater than 113 km/h (70 mph) the fan is disabled and will not turn "ON"

^ If A/C is requested and refrigerant pressure sensor indicates approximately 20 psi or greater the fan is turned "ON"

^ When the ECM is operating in backup the fan will be "ON"

^ When any A/C DTC is set the fan will be "ON"

Location:
The cooling fan relays are located in the underhood electrical center.