Test an Auto Fan Blower Motor

Air is circulated throughout the passenger compartment of your vehicle by a simple electric fan motor. Usually located under the passenger side of the dash, this motor can fail from time to time. Testing the motor itself is the fist step in diagnosing HVAC (Heating/Ventilation/Air Conditioning) blower speed or control problems.

Locate and remove trim covers under the right side (passenger side) of the dash to gain access to the blower motor. These are held in place by an assortment of push-in clips, 5.5mm or 7mm screws. Use a 1/4-inch drive socket set to remove the screws and needle-nose pliers to remove the clips.

Locate the blower motor. It is usually bolted to the evaporator case (the black plastic housing under the dash) under the passenger side of the dash behind and below the glove box. Unplug the electrical connector to allow testing of the motor and controls.

Check resistance of the blower motor with a DVOM. Resistance should be low, but there should be some resistance. An exact specification for your car is available online (see Resources). If near zero or infinite resistance is found, the motor is bad.

Check the power and ground to the blower motor with the circuit tester. On motors with a one-wire connector, power is supplied to the one wire, and ground is found through the motor housing. On two-wire connectors, power will be found on one of the wires and ground on the other. This test checks the controls, and should be run with the key and the blower motor control on.