The compressor worked just fine until I shut it off for about 1 minute and tried to turn it back on. The pump motor makes a humming or buzzing sound, not the usual pump sound. If I leave it buzzing for too long (maybe 5 seconds) it trips the breaker, so I don’t do that for fear that I’m burning something up internally. I unplugged it, drained air pressure, and let it cool down overnight for 12 hours. The problem still exists. There were no sounds or physical indications that the pump or compressor had a problem before shutting it off when it reached 100psi.
It was plugged directly into an outlet without an extension cord. I’ve been using it in this manner for 3 years without problems. I’ve tried several outlets, (GFCI, non-GFCI, and unused circuits), but there is no change. It is a 25 gallon, Sears/Craftsman, 175psi air compressor. It has a red lever switch for OFF and AUTO positions. I haven’t located any reset switch.
Are there internal fuses? Is there a reset switch? Any other ideas or something I can check?
First, thanks for writing in.
Second, thanks too for such a good description of the issue.
From the sounds of it, you either have a failed capcitor or a failed motor.
Since compressor motors (along with all AC electric motors) require an “inrush” of energy to start, a capacitor is used to “jump start” the motor, since there’s not enough amperage in the typical home circuit to start the motor.
If the capacitor fails, then the motors can’t start, and it sits and hums until it pulls too many amps and pops the breaker.
Could be the motor, but I’d bet on the capacitor. Since the capacitor is cheaper to replace than a motor, if you want to do it yourself, start there. If you are taking it to a shop, they can tell you pretty quickly which is causing your problem.