A/C problem repaired

[rohrmann]

A couple of months ago, while in Missouri, we were in our Montana with the front A/C running during a heavy rain and thunderstorm, and the unit started doing weird things, so quickly shut down the thermostat. After things settled down, went to start the A/C again, and nothing. Checked for breaker tripped, it was good. Checked for power at the A/C, and that was good also. The thermostat still worked, operating the rear unit, and there were no fault codes.

After quite a bit of thought, I checked the control box under the unit, which is accessed behind the return filter grill. This is a Dometic CCC II thermostat system using the Multi zone kits at each A/C unit. I removed the box from the front A/C, and opened the cover. What I found was corrosion on the circuit board, apparently from moisture. There has been no leaking, so I assume it is condensation which caused the corrosion.

I ordered a new box, which is part of the Dometic Multi Zone Kit for the CCC II thermostat system. I received the new kit today, maybe 20 minutes to replace with the new box. We now have the front A/C working again.

Just thought this would help with those that have no obvious issues causing their A/C to not work. Less than $100 for the kit, and very easy to replace. Just make sure the 120 volt breaker is off prior to working on this.

[1retired06]

Good info, thanks!

[DQDick]

Good job of diagnosis and repair.