Furnace Blower Motor Capacitor Test

Using a capacitor tester to test the capacitor.

Furnace blower motor capacitor test.

If you re concerned that your furnace capacitor isn t operating properly you can test it by following a few simple steps. If a motor doesn t have the torque to turn the blower wheel or the fan belt it won t start. If it not you probably have a failed capacitor. Excessive heat in the motor can cause the motor to malfunction.

Remove the wires that are connected to the terminals. First the power supply should be shut off then the two terminals on the capacitor should. Look at the wiring digram on the back of the furnace. Buy when you get up there there are a couple of wires coming off the blower motor.

Set your voltmeter to the capacitor setting and connect the meter to the terminals on the capacitor. I dont know how savy you are. A capacitor helps the motor run and gives it more torque. When the motor generally goes south the motor itself it will trip the breaker.

A faulty capacitor will not be able to hold the charge necessary to run the blower motor properly. A furnace usually uses a run capacitor to maintain a relatively constant voltage supply to the blower motor. Locate the capacitor inside your appliance capacitors are metal tubes that store an electric charge usually found near a motor in the appliance. How to test start capacitors on furnace blowers.

For example if your capacitor says 50 5 the acceptable capacitance range is 47 5 to 52 5 f. So the capacitor plays a big role. If the capacitance number went up infinitely to the limit of your multimeter the capacitor has shorted out and should be replaced. Faulty capacitors lead to overheating intermittent motor operation humming noises or even outright blower motor failure.

This will cause the motor to run slowly causing excess heat. Failed capacitor would be my guess if no blower. How to test start capacitors on furnace blowers. If you notice your furnace s motor cycling frequently you should test the capacitor.

Set your voltmeter to the capacitor. Inspect the capacitor visually for signs of damage. Inspect the capacitor visually for signs of damage. Some capacitors will have a set capacitance with an acceptable percentage of variance.

The capacitors on most of residential blower motors are very small so technicians tend to overlook them. Check the capacitor rating on the side of the unit.