Subaru radiator fan wiring diagram
Learn how to diagnose overheating problems with this Subaru radiator fan wiring diagram
Most Subaru boxer engines have two radiator fans; one main fan and one sub fan for the AC. The ECM uses temperature data from the engine coolant temperature sensor to turn on the main fan and turns on the sub fan when the driver operates the AC. Follow how the radiator fans work using the Subaru radiator fan wiring diagram below.
Subaru radiator fan components
2 fuses to power the three relay control coils
2 25A fuses to power the two fans
3 relays: Main Fan Relay 1, Main Fan Relay 2, and Sub Fan Relay.
Subaru radiator fan wiring diagram with engine running but no cooling needed
Power to the control coil of Main Fan Relay 1 is provided by Fuse 26. The control coil on Main Fan Relay 2 also gets power from Fuse 26. No cooling is needed, so no power is switched to the radiator fan.
Engine running cooling needed
ECT shows cooling is needed. The ECT provides ground to Main Fan Relays 1 and 2. The contacts in Main Fan Relay 1 Switch power from Fuse 2 to Main Fan. The contacts in Main Fan relay 2 switch to provide ground for the sub fan when it’s needed
Engine running, both fans on
The ECM can activate the sub fan for increased cooling due to ambient conditions or when the driver activates the AC. The Sub Fan Relay Control Coil gets power from Fuse 22 and ground from the ECM. When activated, the sub fan relay contact switch power to the sub fan and the fan gets ground through the contacts of main relay 2.
