Furnace Blower Motor Capacitor Test

How to test start capacitors on furnace blowers.

Furnace blower motor capacitor test.

If a motor doesn t have the torque to turn the blower wheel or the fan belt it won t start. For example if your capacitor says 50 5 the acceptable capacitance range is 47 5 to 52 5 f. A capacitor helps the motor run and gives it more torque. Inspect the capacitor visually for signs of damage.

The capacitors on most of residential blower motors are very small so technicians tend to overlook them. Set your voltmeter to the capacitor. How to test start capacitors on furnace blowers. If you re concerned that your furnace capacitor isn t operating properly you can test it by following a few simple steps.

Remove the wires that are connected to the terminals. Failed capacitor would be my guess if no blower. A faulty capacitor will not be able to hold the charge necessary to run the blower motor properly. Although only pros should test or repair capacitors you can examine your.

Buy when you get up there there are a couple of wires coming off the blower motor. Look at the wiring digram on the back of the furnace. Inspect the capacitor visually for signs of damage. If it not you probably have a failed capacitor.

First the power supply should be shut off then the two terminals on the capacitor should. So the capacitor plays a big role. Faulty capacitors lead to overheating intermittent motor operation humming noises or even outright blower motor failure. Check the capacitor rating on the side of the unit.

When the motor generally goes south the motor itself it will trip the breaker. Locate the capacitor inside your appliance capacitors are metal tubes that store an electric charge usually found near a motor in the appliance. A furnace usually uses a run capacitor to maintain a relatively constant voltage supply to the blower motor. I dont know how savy you are.

Using a capacitor tester to test the capacitor. This will cause the motor to run slowly causing excess heat. Set your voltmeter to the capacitor setting and connect the meter to the terminals on the capacitor. Remove the wires that are connected to the terminals.

Some capacitors will have a set capacitance with an acceptable percentage of variance. If the capacitance number went up infinitely to the limit of your multimeter the capacitor has shorted out and should be replaced.