Air Compressor labors before cutting out.

by Tex
(Sydney Australia)

Hi, on initial (cold) start-up the compressor sometimes works OK and reaches the nominal pressure although I've noticed that it now stops in the red band of the pressure gage.

But most of the time the twin V compressor starts up OK but starts to labor almost immediate and cuts out altogether.

Suspect there is a thermal overload that is cutting in as cycling the ON/OFF switch will sometimes allow the compressor to start up (and labor again) but most of the time cycling the ON/OFF switch does nothing (ie compressor doesn't work).

Once the compressor is left for a couple of hours (probably cools) the senario is repeated. Suspect the pressure switch, is there a way to confirm this? Cheers

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Bill says....

And cheers back to you, Tex!

Here's a question: "reaches the nominal pressure although I've noticed that it now stops in the red band of the pressure gage." What is the "nomial" cut out pressure, and the red band you speak of, is that a higher pressure setting than the normal cut out? If so, I believe this points to a pressure switch issue.

But this... "the twin V compressor starts up OK but starts to labor almost immediate and cuts out altogether. " isn't the pressure switch, I don't think. If the pressure switch trips, power flows or is cut off. It's possible, but almost too rare to be accepted, that a pressure switch might somehow throttle the power to the motor to cause lugging. I'd look to a start or run capacitor for this symptom, assuming that the motor is in good shape.

Cheers,

Bill