I had my Dometic CCC2 thermostat fail last year and ordered a new one from Dyers,
www.dyersonline.com It came pretty quick and with shipping, was a little over $100. A couple years ago, we had the front A/C start acting really strange, so shut it off and just ran the main one. After some investigating, I opened up the cover on the control box above the ceiling vent, and found the circuit board had corrosion over most of it. I replaced the control box and everything was working again.