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Topic: Dometic CCC2 Thermostat Shows 32 Degree; A/C Cannot Work (Read 349 times) previous topic - next topic
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Dometic CCC2 Thermostat Shows 32 Degree; A/C Cannot Work
Got an issue with the Dometic A/C on our 2015 MB.  With power on the thermostat “inside temp” reads 32 degrees F. It reads correctly in the off position.   So, the A/C will not turn on since the thermostat reads the inside temp colder than the A/C set point.  We have read internet solutions to the same/similar issue.  We have double checked the Fahrenheit/Celcius setting, did several factory resets on the thermostat and have disconnected/reconnected the thermostat.  We have removed the interior AC/C vent cover and are currently using fans to blow air up into the unit and onto the communications module (hoping this works).  We were just camping on the beach with some light rain and humidity 70% and above. It worked until we broke camp this morning.  It started reading this 32 degrees on our first break when we tried to run the A/C on generator. 

Can anyone suggest anything else to trouble shoot? Thanks in advance for your thoughts.
Don & Tery
2022 MB 27.5 towing a 2022 Wrangler
Re: Dometic CCC2 Thermostat Shows 32 Degree; A/C Cannot Work
Reply #1 –
Hi Don; With that high a humidity it is possible that the AC was freezing a bunch of water inside the cooling fins of the A/C.  Usually this turns off the compressor while letting the fans run, to melt any ice build up.  It might take awhile to resume normal operation.
   Otherwise I don't know anything about this A/C unit, or the Comfort Control Center thermostat.  So I just looked up issues with Google. I'm probably just repeating what you have already done. "Make sure the temperature read out is actually set for Fahrenheit."  Quote Google :
"Ensure the thermostat is not set to Celsius. Press the up and down (plus and minus) arrows simultaneously to switch back to Fahrenheit. "  My other thought is some water condensate got into the electronics, so running the fan for awhile might dry it out and have it start reading/acting correctly again.  Possibly a bad connection at an internal connector. The internet seems to think that it could have just failed. Replacement of the control panel or thermostat being the cure.
    There is a built in reset function. (you've probably done this already) "The CCC2 thermostat has a reset function. Press and hold the "Mode" and "Zone" buttons simultaneously. The display will show "IniT", then release the buttons. Press the "On/Off" button to exit the reset.
This can resolve minor glitches in the thermostat's operation. "    
   Giving us the model number might help us look up other solutions.
    I did find this YouTube that brings up rain and high humidity causing moisture in the drip tray and that some wiring may be wet, causing this problem.
    dometic CCC2 thermostat for roof unit for RV, shows 32 degrees problem -...  I hope this helps, no parts needed!       RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Dometic CCC2 Thermostat Shows 32 Degree; A/C Cannot Work
Reply #2 –
Hi Don; It occurred to me that you might not be able to watch that video; The answer was that a two wire connector along with a bundle of extra wire was just shoved up into a sort of empty space above the vent screen of the A/C unit.  The two bare wires ended up in the drip tray and got wet, causing the erroneous 32 degree reading. Drying out that connector and keeping it out of the drip tray fixed his problem. I hope that was what you had.  RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Dometic CCC2 Thermostat Shows 32 Degree; A/C Cannot Work
Reply #3 –
Ron,

Thanks for your research and advice!  We continued drying it out by running the a/c in the fan mode at hi speed for several hours. The thermostat works correctly now. Once we have time, we need to look more closely at the communications module and control board for corrosion, susceptibility to moisture intrusion, and proximity to the drip tray.

Thanks again.
Don & Tery

Quote

On May 30, 2025, at 01:16, RonB
Don & Tery
2022 MB 27.5 towing a 2022 Wrangler