Air compressor does not shut off

check all the lines and the Drain valve for leaks. I can think of only a few things: a leak OR the pressuretrol is bad. I would hunt for leaks as I first suggested. If you have an air hose attached disconnect it, run the compressor and see it problem goes away. If nothing changes then problem is in the compressor itself. If this is an older unit may also be a hole in the air tank itself from internal rust. If that turns out to be the problem STOP USING IT IMMEDIATELY scrap it.:yes: