If the compressor has been fine on this outlet before and the problem is just begining. The current draw will have to be checked at the breaker, you might have a breaker which is tripping prematurly. This is best left to an electrician. If you plug the compressor into another outlet operated by another breaker and the compressor runs fine, the outlet it is tripping on and it's breaker will be at fault, if the compressor is tripping any given outlets breaker, the compressor is at fault and most likly the motor brushes are worn causing excessive current draw, also if the oil level is low this will cause excessive resistance to the motor, in turn tripping the breaker. From my experience it is often cheaper to replace the compressor rather than fix it, however, Sears does ofer a competitive service program fro repairs.
-Rip
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