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Air compressor trips breaker after it has built pressure.starts fine with no pressure in tank. But when it goes for it first cycle it trips the breaker (20 amp dedicated breaker)

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  • dennisstable Sep 08, 2009

    Thanks for the response. That gives me some "food for thought" in that if I start using it and not let it reach max pressure (were it would shut off and than start cycling) I should be able to keep it going.

  • A Miller May 11, 2010

    I have a similar problem with a Sears 220 VAC 20 amp machine but only when it is working hard and the motor is hot. Consequently, I avoid restarts by using air continuously (as in sand blasting). I also run a fan on the machine to help get rid of heat. Actually, mine is not a breaker problem but a overload/overtemp trip on the motor. When it goes out, I must wait for the motor to cool and then I reset the motor. No answer for your problem but I hope this helps.



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You have air leaking back to the cylinder which means when it goes on the compression stroke the air in the tanks have gone in to the cylinder and this makes it hard for the piston to go up on the tank from the pump is a pipe that leads into a gold non return valve this has a rubber ring and a spring inside take this out and turnit over then try this obviously draining the tank if this doesnt help check the oil level and if thats ok your motor must be seizing up on bearings get back to me buddy

Posted on Sep 07, 2009

  • ollie reece-jones
    ollie reece-jones Sep 08, 2009

    yes buddy basically if its at 150psi i will reduce it till it is 100psi this will extend the compressors life as its not working as hard to reach the max pressure reduce this by where the pressure switch is un screw the little screw in the middle off the cover then take it off then under neith you will see a gold or silver nut 10mm unscrew this to decrease pressure go to 100psi



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Do you have any other electrical appliance in the circuit that might cycle on when the compressor is starting? If there isn't enough current to go around, that might be an issue.
it could be a failing pressure switch.
Check your unloader valve. I think that it has failed, and as a result, the motor can't overcome the additional load on start up.
If the compressor is blowing the breaker, you know that it's either a short of some kind, or the electrical motor is pulling more amps than the circuit can handle..
If you are sure that it's not a short, and the motor actually starts (it's not the capacitor), and the motor shaft turns easily (meaning that the power train into the compressor head is not binding in some way and overloading the motor) then it's got to be the motor that's at fault.
Try this. Unplug the compressor, drain the tank all the way down to no PSI on the gauge, close the tank drain, and plug it back in / start the compressor.

Does it start?
I suspect either you are overheating your compressor to the point where it starts to seize (thus drawing more amps and popping the breaker) or you've already damaged the motor and it's cycle gets shorter and shorter before it's overheated to the point of seizing.

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