Pulled in yesterday to a site, a little high in the REAR. Pressed the buttons to level, and it went thru the gyrations. It finally stopped, with a light indicating that the FRONT was high, seemed pretty level to me. Shut off the system, then turned back on & set it to level again (front light still on). Went thru the gyrations again, same results, so I just accepted it. After a few minutes the 12V compressor came on, and stayed on. The PSV was popping off, I tried unplugging all of the plugs I could readily see & reach & it kept running. Turned off the "salesman" switch & it kept running. Finally disconnected the house batteries & killed it. Smacking the pressure switch didn't help, but after everything calmed down, it checks out fine. Any suggestions ? Seems to be a large relay right behind the compressor....maybe ? But if it was stuck, why would it release when I shut off the power ? Has not repeated.
I just did a whole write up on the possible culprit a couple weeks ago. It can be intermittent, which is a little more problem to troubleshoot until it happens again.