Defective temperature switch, coolant sensor or other sensor. Engine thermostat is stuck OPEN (engine never gets hot enough to turn on the fan) Faulty fan relay. A wiring problem (blown fuse, loose or corroded connector, shorts, opens, etc.)

How to Check a Radiator Fan

1. Determine whether your radiator fan is manual or electric.
2. To check an electric radiator fan, start the car and let it get up to the temperature where the fan normally kicks on.
3. Use the volt meter to test if there is power to the wires.
4. Normal voltage for a radiator fan is around 12 volts.

To check the temperature at which the fan comes on, turn the A/C off and keep the engine running until it reaches normal operating temperature. Most fans should come on when the coolant reaches about 200 to 230 degrees. An electric fan SHOULD NOT run all the time.

The fan relay is usually located near the bottom of the engine compartment on a metal frame member. The metal acts as a heat sink to keep the fan relay cool. So, unplug the connector at the relay and repeat the check for power. If you get power, you’ve got a bum relay.

The cooling fan control module in your vehicle is located at the front left of the engine compartment next to the radiator.

To test a fan motor, unplug the electrical connector at the motor and use fused jumper wires to connect battery power and ground directly to the fan. If the fan does not operate, replace the motor. 2. If the motor tests OK, check the cooling fan thermo switch, located at the bottom of the radiator on the driver’s side.

An A/C fan control module helps to control the blower that supplies air to the cabin of a vehicle, as well as the cooling fans. The module helps to make sure that the cool air that is produced within the A/C system of a car is blown into the cabin.