I have a Harbor Freight (I know, I know) air compressor. It's the 21 gallon, 2 1/2 HP model.
The problem is that when the tank is empty it starts fine, and pressurizes the tank to where it should be. Once I start to use an air tool and the tank pressure drops below the trip point, the compressor will strain, not move, and then pop the breaker on the outlet strip. There is nothing else on that strip, it's just a way to extend the length of the power cord a short distance. The trip is slow, so the breaker in the strip is being strained, but not badly. If I empty the tank, it will immediately start up when I flip the power switch.
There is a valve in the top of the cylinder head, that seems to be there to allow the air trapped in the cylinder head to escape when the compressor first starts up. This allows the motor to get up to speed before trying to make it do any work. This seems to function correctly when the tank is empty. It lets the first 20 seconds of air out, then closes and the tank pressurizes. Can I assume it should do the same thing when the tank is just passed the refill pressure? I have not tested that it has, but I will.
One other thing, the freezer in the garage is on the same circuit. I have not tested a correlation between failing to start and the freezer running at the same time. How sensitive to voltage drops is a compressor this size? It's wired for 117AC by the way.
Oh, I thought it might be the compressor, so I returned the original one I had (same make and model) and the new one does it to. It must be something in my environment at home. I figure power, or temperature. It's been cold in the garage this season.
Oh, and I followed the instructions on oiling. I put the right kind of oil in it, ran it through break-in, plus another 30 minutes or so, and then changed the oil again. Nothing suspicious in the oil that I could see.
This is driving me nuts. Any thoughts?