Dometic thermostat malfunction.

update ..........got the manual out and said to do a reset on the ther.The inside now reads "somewhat" better,not ridiculous low temps, but it is not cycling right. I will see more tomorrow if we have to use the ac.

Could be bad thermostat but at $130 per copy be sure. You can't return electronic items. Clean all contacts where the communication wire runs to. Both where the plug plugs into and on the boards in the AC unit.

We had this same issue on our bedroom AC unit when we went to do the PDI on our trailer. Inside temp was reading way low and the AC would not function correctly. It turned out to be a defective thermister (temp sensor) on the bedroom AC unit. Our thermostat controls both zones and the living room was functioning fine. They replaced the thermostat first and that did not fix it. They replaced the wire from the AC down to where the sensor mounts and that did the trick.

A little update, after fooling with the sensor and watching the inside temp reading, i think its just a thermostat gone bad, The inside temp will all of a sudden read in the high 70's, ac will come on, inside temp on the thermostat will drop to 40's in a few seconds, ac will turn off in the auto mode and thermostat will then show 70's again and go thru the cycle again. I even pulled the wire out of the wall a little way,s and covered the sensor with a heavy piece of cloth. Bad thermostat or what?

Try resetting it. Try holding top and bottom buttons in while turning the thermo off then on after a second or so It shd come up with a "FF" reading. Then release the botttom button and next the top button. Now turn it off then back on and see if it is better.