Air compressor repair

[AC-WC]

I have an older Craftsman air compressor and am pretty sure I need a new pressure switch. 20 gal/5 hp 220v. I turned it on, it built up pressure and kept going. Wasn't paying close attention and then heard air hissing (major leak) coming from the compressor. Shut it off, thinking I blew a hose and then started investigating. Verified no blown hoses, turned on again and it would not shut off on it's own at 150psi (normally shuts off at 125/130). Did I make the right diagnosis?

 

[The Cobbler]

sounds like you did for sure.
the hissing is the overpressure relief is opening & doing it's job

 

[micromind]

Yep, bad pressure switch. Unless the wiring has been messed with........then it's anybody's guess.

 

[AC-WC]

Follow up-actually found my owners manual for the compressor, ordered part, installed a few minutes ago and back to normal!
Thanks!!!