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The air conditioning in one zone of my house isn't turning. I have a Goodman air conditioning unit in that zone. I noticed that the fan motor was very hot (estimate 150 degrees F). It was much hotter than the other unit that was working. I disassembled it enough to be able to turn the fan with my hand and the bearings feel good. I tried flicking the fan with a screwdriver with it assembled, but it didn't start up. It seems like the start capacitor is a common problem, but I wouldn't expect the motor would be so hot if that were bad.

I turned off the power and let the fan cool off, but it didn't help. I didn't hear any humming or anything. Any idea what could be wrong?

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Depending on the type of motor, it might be the centrifugal switch, not the capacitor. Either way, remove the motor and take it to a motor shop before you burn it up. If it's a capacitor or a centrifugal switch, they can repair that for you inexpensively. If the windings are damaged, it's too expensive to repair and you would just replace it.

  • I removed the motor and cap and tested them. The cap seemed bad, but I didn't have a lot of faith in my ability to test it. The fan spun freely and I had continuity between 2 out of 3 leads, but not continuity to ground, but I didn't want to have to take it apart again so I brought everything to the motor shop. They confirmed my suspicions and sold me a new cap for $16.78. It fixed my AC unit. – Eric Jul 26 at 20:22
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Your idea that the capacitor is bad is probably correct. With a bad capacitor, the fan can't kick off and start turning, but there is still electricity running through it. No fan turning means no cooling so that heat builds up. Having a capacitor go bad unnoticed can actually damage the fan as well because of this heat.

You tried turning the fan, which is a good troubleshooting step. Since it does turn, replace the (inexpensive) capacitor. If the motor doesn't come on after that, it could be damaged. You could try to check the resistance of the motor coils, but you'd need to find a reference for your fan motor to know what "good" was.

  • With hvac the most common motor problem is a bad cap. Look at the cap if the top or bottom is bulging at all change it out, 150 is about right for a bad cap two hot to keep your hand on but the magic smoke is still inside the motor. Change the cap as jphi1618 recommends stay within 10% of the value measured in uf or microfarads if you can’t find the correct value and make sure the voltage rating is the same or higher than the current one. + – Ed Beal Jul 25 at 14:27

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