Engine Cooling Fan: Operation

Electric cooling fan is controlled by a coolant temperature sensor, diode assembly and fan relay. When coolant temperature reaches 188°F (87°C), coolant temperature sensor contacts close and supply voltage to fan relay. Relay contacts are then closed turning on cooling fan. On A/C equipped vehicles, the A/C compressor clutch relay energizes cooling fan relay. When A/C clutch is energized, cooling fan runs. System is protected by a fusible link from battery to cooling fan relay.