Electric Cooling Fans: Description

NOTE: For more extensive cooling fan system testing procedures, see appropriate MANUAL A/C-HEATER SYSTEMS article in HVAC.

Fan control module supplies voltage to relay coils. Relays are grounded by either the radiator fan switch "A", "B" or the PCM. Grounding relays energizes their coils and supplies battery voltage to radiator and condenser fan motors. Fans run until ground is removed from relay coils. If engine coolant temperature is more than 212°F (100°C) when you turn the ignition switch to LOCK, the radiator fan control module will turn on the radiator fan and let it run for about 15 minutes.