Compressor Won't Shut Off

by Janice
(Norcatur, Kansas USA)

Question: When camping this last weekend and it was very hot. No problems until the next morning when noticed that the compressor wouldn't shut off when the camper was cooled enough. Shutting everything off on the thermostat would not shut the compressor off either. We have a 1999 Coachman with a Duo-therm roof unit. We ran the fan on the unit all night long and most likely the compressor was cycling on and off all night. From what we could figure out the only reason the compressor was cycling was because of overload switch. Also the next morning the unit had frozen over. Got it thawed out, but same thing happened the next night.

Robbie: You could have a short in the wall thermastat or most likely have a relay stuck on your computer control board. Be sure you have an RV tech replace the board if it needs to be done. There are settings to be made on the new board and should be done by a Qualified tech. I suggest you turn off the curcuit breaker in your control Panel to the Roof AC to prevent damage to the compressor and call a tech ASAP. Hope this helps.

Thanks for the Question Good Luck,

Comments for Compressor Won't Shut Off

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Jun 09, 2013
What if...
by: Sissy

We are having the same problem. We replaced the top unit, replaced the thermostat, and replaced the low temp switch...still doing it. Any ideas?

Dec 13, 2014
compressor won't shut off
by: curtis

I keep my power cord to my montana 5th wheel plugged in with nothing powered up. Suddenly my A/C compressor started running and nothing else. Thermostat, fan, etc in off position. Any ideas?

Aug 13, 2015
easy fix
by: jason boyd

The relay is located in the lower unit. Remove the bottom cover and you normally will see a small square box,with all the wires going to it. make sure the breaker is off, you'll need a Phillips and a 1/4 in nut driver.
Unscrew the box supports and let it hang, normally there ate 5 1/4 in. Screws holding the box cover on. Remove the screws and remove the box cover plate. See the control board? There is a black relay in the board with two wires going to it. If you see Noooooooooooo burnt wires. renove the wire that does not go to the yellow wire nuts that tie directly into the power. Let it hang and ensure that it's not touching anything. Turn the power back on. Bam! Your compressor is not running. Turn off the power. Tap the relay with the handle end of the screwdriver, reconnect they wire to the relay. And turn the power on. See if your compressor will shut off with the thermostat now. If it does, great. If it didn't, that's ok too. Either way, order the board from PPL on line. And when it gets there , just follow the instructions. Good luck!

Sep 03, 2015
compressor not shutting off
by: Anonymous

We have a 2001 winnebago with a basement air conditioner and not shutting off?

Feb 15, 2016
Relay Box?
by: Kelly C

I just noticed that in my 2006 Forest River Wildwood. I took the cover off and the noise is coming from the metal box (I am assuming it is a relay box of some sort. It just started doing it this afternoon and I have to go to work but have cut off the power to my camper as I am afraid I may damage the entire unit. I will have to look at it tomorrow. The RV guy wants $200 for just coming out even if it a inexpensive fix. I will have to deal with it myself and try taking the box apart.

Aug 02, 2016
compressor & ac won't turn off.
by: Becky

Installed a new thermostat and ac works good but won't turn off. Even when set on highest temp. We turn it off when we get too cold. Bills will be high if running so much. Thanks!

Aug 14, 2016
Thanks Jason Boyd
by: PJ

Thanks to Jason Boyd I am running again. My problem started with a bad thermostat, it was basically on/off. I replaced the T stat but I found that although the unit would now cycle on/off the condenser was always on unless I shut it off at the panel. So with the breaker off I unplugged the lower unit harness, removed the screws holding the box in place so I could lower it and smacked the hell out of the box with the screwdriver handle. Put it back together and when I turned the breaker back on the condenser stayed off until I turned it on by the t stat. Even if I have to do that every once in a while that's fine by me. I heard that you need to have new relay boards programmed or something so repairing is not in the budget right now.

Thanks Jason!

Jul 21, 2017
Thank you Jason!!! NEW
by: Josh and Pipes

Took your advice and the compressor is working properly! I am as unhandy as they come and my girlfriemd and I took it apart , gave it a couple of taps and the ac is purring! Thanks again!

Aug 28, 2017
Thank you NEW
by: Anonymous

Thank you Jason Boyd! All is working as it should, after following your instructions!

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Robbie Warford, San Diego RV Repair

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