Dometic AC issue

[JCP]

3791RD
When I run my furnace the rear AC unit fan turns on blowing cool air. Furnace works fine. Don’t know why or how to shut the blower off. I did a hard reset on the system. Anybody come across this?

 

[Carl n Susan]

I am pretty sure it is due the fan not being set to Auto when in furnace mode. The AC fan will blow air to ostensibly "circulate" the existing air but doesn't cool it. It sill feels like cold air. Ste th fan t Auto to stop this.

This is a common issue, but I could only find one Thread with the solution. I know the are many more.

Dometic Thermostat Mind of it's own ?

So we've got a 2019 Montana 3721RL and recently our thermostat when set to call for heat will not only start the furnace but the rear roof top a/c unit kicks on same time. In fact the rear a/c unit doesn't appear to cycle the a/c at various temps when cooling. Anyone else experience the same...

www.montanaowners.com

 

[LeftOverParts]

In case you have iN-Command, here’s how the propane and electric heat works together. Also see the note at the bottom.

(Don’t know if the system works like this without iN-Command).

 

[JCP]

I am pretty sure it is due the fan not being set to Auto when in furnace mode. The AC fan will blow air to ostensibly "circulate" the existing air but doesn't cool it. It sill feels like cold air. Ste th fan t Auto to stop this.

This is a common issue, but I could only find one Thread with the solution. I know the are many more.

Dometic Thermostat Mind of it's own ?

So we've got a 2019 Montana 3721RL and recently our thermostat when set to call for heat will not only start the furnace but the rear roof top a/c unit kicks on same time. In fact the rear a/c unit doesn't appear to cycle the a/c at various temps when cooling. Anyone else experience the same...

www.montanaowners.com

Thank you so much! That was the problem!

 

[M&M]

With the iNCommand system, you can set fan to “off” to only run gas furnace.