Craftrsman Compressor trips breaker

[londi430]

Hello I have a craftsmen compressor 20 gallon 1.5 HP model number 921.166420, thats bogs down and trips the breaker. Could this be a switch ? Ran fine before had promblem a with long extension cords, would always pop the breaker on the machine.

[Walt 2002]

What size breaker? Compressors have a relief valve on them that relieves the pressure between the compressor and the storage tank when the compressor stops to make it easier for the motor to start the compressor next time. Sounds like it might not be working.

Walt Conner

[smallen]

motor may be damaged by long cord, voltage drop by long cords can damage the motor, at what pressure does it start to bog down, does it run long enough to build any pressure, will it run if you open the air line so pressure doesnt build high enough for it bog, connect ac clamp amp meter at pressure switch,
check valve at tank may be bad, cause same problem, minus the voltage drop

[motorhead64]

If it is shutting down quickly, it may be the "unloader valve." It is what makes the "shish" noise when the compressor ends its cycle. The noise is the sound of the valve evacuating the pressure above the piston of the compressor. If it doesn't work, the pressure above the piston puts a heavy load on the motor during start up tripping the breaker. It is the "relief valve" that Walt mentioned. MH

[bobodu]

Try plugging it directly into the outlet......
From the owner's manual...." The cord must not exceed 25 feet and and a nominal #12 AWG wire must be used".
This is the reason why you should always use more hose and not more wire.

[londi430]

Now the compressor just hums when I turn it on. The breaker is on the of side the motor do not know what size it is. The pressure would cut out around 60lbs.

[KE4AVB]

Just thoughts...I would disconnect the piston assembly from the motor and see if the motor will run. If still just sits there and hums then you got a bad motor; not listed as available. If it runs without a load I would check the piston and cylinder sleeve to see if they are damaged.

Never have been fun oil less compressors myself.

[mwerles]

It may be a bad capacitor in the motor or a bad start switch.

[londi430]

Thank you KE4AVB I disconnected the piston assembly and the motor ran fine. I put it back together and I notice the fan look bad, there were groove marks in the cover. It must have jam the motor. Now it runs good again. Thank you to all that reply.