Outdoor a/c unit fan motor

Problems related to residential installations.

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Outdoor a/c unit fan motor

Post by Milkdud809 » Thu Sep 13, 2012 9:26 pm

I have a Ducane outside unit that I noticed was buzzing today and the fan was not spinning. The motor model - K48hxffy-3798. I am a mechanic so obviously the first thing I did was bang on the top where the motor sits. It spun a little, so I did it some more, spun a little more, after hitting for about 30 seconds straight it was spinning fast enough to self sustain. I could also feel the heat from the motor. I'm sure the fan motor bearings are bad and the motor needs to be replaced, but while I'm waiting for the new motor to be mailed out will it do damage to the unit if I don't turn it off until the fan is replaced?

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- Outdoor a/c unit fan motor

Post by Freon » Sat Sep 15, 2012 10:34 am

The bearings may be fine. If you hear grinding as the fan blade spins then you may need a new motor.

However your problem is most likely a bad run capacitor. Pull the main disconnect that's close to the condenser unit and open the electrical compartment. You will see the condenser... oval or cylindrical in shape usually with 3 wires at the top. That's a dual capacitor and runs both the fan motor and the compressor motor.

Carefully disconnect the 3 wires labeling them (herm, fan, C) so you know how to reattach. Go buy an identical capacitor. The microfarad values HAVE to be identical. The voltage can be equal to or greater than the stated voltage on the capacitor case.

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