craftsman compressor

First make sure the pressure switch is set in "AUTO" position. If in "RUN" it will not shut off.
 
Now if it doesn't cycle in "AUTO" replace the pressure switch. Bad news here as the original style is no longer available and you need to substitute a suitable replacement. It will need for for air compressors with a pressure release valve or the motor will not be able to start up when the compressor pump is pressurized.

bubblegum
ok thanks for the info... now that being said, i dont understand that last part.
 "It will need for for air compressors with a pressure release valve or the motor will not be able to start up when the compressor pump is pressurized".
what is for for ?

Pressure Release Valve: The pressure release valve located on the side of the pressure switch, is designed to automatically release compressed air from the compressor head and the outlet tube when the air compressor reaches "cut-out" pressure or is shut off. The pressure release valve allows the motor to restart freely. When the motor stops running, air will be heard escaping from this valve for a few seconds. No air should be heard leaking when the motor is running or after the unit reaches "cut-out" pressure.
 
If you don't relieve this via the cutoff switch (relay) then you either burn up your motor or simply will much larger motor then the 2 HP you have, more like 5+hp.