Dometic thermostat malfunction.

[peaeye1]

This is on a Winnebago 5th wheel.This thermostat can be set to one, two or both ac's.Both units work fine,fan,compressor, but the inside temp setting on the thermostat for the 2nd ac is now starting to read down in the 40's and 50's at times.As a result I cannot get the 2'nd ac to come on.At random times it will show in the 80's.I know where the sensor is for the 2nd ac, and have made sure no dust etc was on it. It has worked fine for several months until today. Any thoughts?

[bgum]

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.