I bought a used air compressor of unknown vintage. I checked
everything mechanical, wired it up and it started and ran well. I
expected this because I had seen it running before I bought it.
Anyway, after several starts over maybe 5 days the motor acted like it
was straining to start. Just before I got to the braeker panel the
breaker popped. I first checked the pump and it turned over nicely so
I took off the capacitor cover on the side of the motor and both caps
looked bad. There are two starting caps on this motor connected in
parallel. No run caps. One cap failed to the point that one spade lug
had fallen off due to heating at the point where it was riveted to the
cap. Both caps have vent holes. The cap with the melted off lug had
white stuff coming out of the vent. The other cap did too but there
was less of it. I know that motor start caps fail over time but I
don't know what the fail mechanisms are. This motor did sit idle for
several years before I bought it. Do motor start caps need to be
"re-formed" like the electrolytics found in electronics?
Thanks,
Eric