Dometic AC Question

[Johnhowdy]

Howdy everyone
So I have a weird symptom with my rooftop AC. It's a Dometic with wall mounted digital type thermostat. Don't have a pic but it's basically a black square thermostat with a power/mode button on the left and up/down arrows on the right. It's brand new (2018 trailer). So when I set the fan speed to low and set it to cool, everything works perfect up until the temperature is cooled in the trailer. The fan according to my knowledge is supposed to keep running even when the compressor stops. But everything shuts off. I have to go back into the thermostat settings (fan is still set to low) and basically toggle through the fan mode again (auto hi,low) and set it to low again. At least I think that's what I had to do. In any case it seems like the original settings don't stick and have to redo the process over again. Is there a certain procedure to follow like set to cool first then set the fan? Anyone else have this issue? Cheers

[ionasilverback]

Try resetting the thermostat.....turn thermostat off and simultaneously press and hold the MODE AND ZONE buttons while turning the on/off switch back on. FF should show in the display and release the zone/mode buttons. Then give it a try and see if all works. If you have the dual zone it is about the same except INIT displays and you release the zone/mode buttons and press the on/off switch to exit the set up mode and then turn it on and give it a try. Took these directions ouf of the manual. Good luck

[larry2c]

I have the same thermostat in our TT and when I set it to anything but "Auto" I get strange and unpredictable results (even had the AC and the furnace running at the same time once). The general consensus I have got is that using something other than Auto mode is not advised and the manual we got with the trailer seems to suggest the same thing. I would like to just run the fan at low without the AC compressor running just to move air around but that doesn't seem to be an option.

[Bama Rambler]

Try initializing the thermostat and see if that helps.

"A system initialization will need to be performed by the installer after the system is installed.
Make sure the Single Zone LCD thermostat is in the Off condition.
Press the “+” button and, while holding it, also press and hold the On/Off Mode button for three seconds. LCD will show ― ― .
Press the On/Off Mode button again to turn system off.
This completes the initialization."

[koller1509]

Try selecting the fan using the mode button and set to speed then go back to cool mode and see if it works.