Add
to the previous answers.
These answers assume you are using MPLAB w/IFI or Watson default code.
What are you using?
Tell us what is happening.
--Is the compressor turning on, but not off?
--What color is the compressor Spike light?
--Is your pressure switch wired with only the ground and signal lines (black & white usually), NOT the red wire?
--Is the Spike fuse replaced with a 20a snap-action breaker?