Tools, Sharpening and Power Machinery - Craftsman Air Compressor (electric)

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jepoole
12-19-08, 06:31 PM
I am not sure if I am at the right forum or not.I I have a Craftsman Air Compressor model 919152921,4HP 25 Gallon 110 volt. The problem that I am having is that when I turn it on it turns real slow and trips a 20 amp breaker within seconds. The compressor turns freely by hand. I am not sure if this could be caused by the start capacitor or run capacitor. I am not an electrician. Please advise.

Tolyn Ironhand
12-19-08, 07:50 PM
If this compressor is an oil one, and it is cold, it may just not have enough "oomph" to turn it. I have an off brand compressor and if it is not warm, it will not run. Just keeps tripping the motor overload. (not that I let it do that) I have thought of using synthetic oil in mine but haven't had a chance to test the theory
WFOWFO
12-19-08, 08:03 PM
Take the belt off and try it without the compressor. Offhand it sounds like a start cap.

jepoole
12-21-08, 03:34 AM
I guess I left out some key information. It is oilles,single cylinder, direct drive manufactured 9/94.
wirenut1110
12-21-08, 06:50 AM
One thing I see often on air-compressors stalling at start is the "unloader valve" (the valve that releases pressure from the head when it turns off) is stuck or clogged or a check valve that's letting air go back back on the head. If the head has pressure on it, it won't start because the motor won't be able to overcome the head pressure. I'm not sure if, when you tried to start it, it had air in the tank. If not this isn't your problem.