heater issue

[Charlie W]

I have a 2018 Montana 3701LK.
When I turn my air conditioner on it works fine, but when I turn my heater on the air conditioner comes on and it blowing cold air and the heat come out of the floor, if I turn the heat pump on everything's fine.
It just started yesterday it has been working fine before that. I am thinking thermostat is the black Domestic digital one.


Thanks Charlie

[Carl n Susan]

This is a common complaint due to a "feature" of the Dometic thermostat. I seem to remember the manual actually documents this behavior but I don't recall the specific reference.

Anyway, these systems can have the fan running on the A/C if the system calls for heat and the fan setting on the thermostat is set to anything other than AUTO

[Charlie W]

Thanks that was it somehow it got turned off of Auto