I have a problem with my furnace blower. You can hear it trying to start but it doesn't. It's a 115V motor, 1/3 hp, 6.6A. I put an amp meter on hot leading to motor and it drew 20.9Amps. What could it be? The motor is not seized because I am able to turn the pulley by hand. Could the transformer or the switching relay be the problem. Help is appreciated.:D

Is it capacitor start? If so, disconnect one lead and short it out. Then connect an ohmmeter across the terminals. If it is good, It should show an initial reading, but climb off scale. If it shows open or a constant, low reading, you have found the problem. Let an electrical or HVAC supply match it.

No, it is not capacitor start. I unplugged the switching relay and checked continuity according to the diagram printed on the relay. All checked out. But the two unnumbered prongs, which I assumed are the hot and neutral prongs, also gives me a continuity read. Could they be shorted?

Ken:confused:

You have a shorted winding in the motor. Will need to be replaced...

Quote:

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Originally Posted by rickdb1

You have a shorted winding in the motor. Will need to be replaced....

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Yes it sounds more like a shorted winding and bad motor than anything else. I'm surprised it doesn't blow the breaker or SSU fuse.

Just replaced the motor today and now the breaker trips. Could it be a bad transformer?

If the transformer was bad, the relay would never get the signal to connect the blower. How many leads did the new blower motor have? Enough that you could have connected the wrong one somewhere? One more thing, disconnect the motor and hit the switch, If the breaker trips, you have a wiring problem somewhere else.

I misread the pinout. Everything is connected correctly. New problem. The motor runs continuously. What is CW shaft and a CCW shaft?

Rotation. Clockwise/CounterClockWise...