Air compressor motor not working. What are some common problems I can check?


Old 08-14-13, 06:57 PM
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Air compressor motor not working. What are some common problems I can check?

My air compressor (80gal, 6.5hp, Black Max) recently stopped working completely. I have used all of the air in the tank, but the motor did not turn back on. The breaker did not trip and there is voltage on the motor side of the pressure switch so I believe the problem is with the motor or a component in the motor.

I cleaned up the contacts with some fine grit sandpaper but this changed nothing.
I have watched some youtube videos of people checking capacitors with analog voltmeters. Is there a way to do this with a digital multimeter?

What are some other things I should check? I have been told to check resistance of the windings and contacts but I am unsure of how to do this. I can't find much info online for this specific motor. Any ideas will be helpful. Thank you.
Old 08-14-13, 07:23 PM
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Welcome to the forums.

If you had a bad capacitor you would hear the motor humming.

I'm guessing this is a 240vac motor. Did you open the motor junction plate and check for power there ?
Old 08-15-13, 02:13 PM
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If I were you, I'd turn off or unplug the power, pull the wires off of the pressure switch and connect them to bypass the switch, and briefly restore power. With the switch bypassed it should simply kick on, but don't leave it that way.

If it runs this way then something's wrong with the pressure switch.

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