won't restart to refill tank

after the first filling and air is used, power is sent to motor and breaker trips as if unloader isn't working.

And, does it matter what "size" pressure switch in terms of h.p. rating. Could this affect or cause this problem

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Bill says...

You say it is "as if unloader isn't working". Is the unloader dumping air when the compressor reaches the cut out pressure setting and stops?

Regarding the pressure switch, it is a mechanical switch being operated on by an air diaphragm or piston, so the switch has to be capable of handling the pressure ranges on the system to which it is attached. The HP of the switch rating will have more to do, I should think, of the point ratings to ensure that they can handle the power flow when necessary.

Cheers,

Bill