Rooftop Dometic Runs with Furnace

[masterdrago]

Whenever I switch the wall thermostat to "furnace" in either the bedroom or kitchen/living, the related a/c unit runs the fan on the roof. The air coming out the ceiling vents is room temperature. When the fan cycles on to bring warm air out of the floor vents, the rooftop unit will continue to have the indoor fan run. Is this what others are seeing?

[DQDick]

Most likely you have the thermostat set for the fan to run on high or low. When you run the furnace the fan must be set on auto.

[Carl n Susan]

X2 what DQDick wrote. The fan must be set to AUTO when in furnace mode. Otherwise the fans in the A/C kick in. I know it doesn't make sense, but that is the way it is.

[BuilderBob]

You need put the furnace in auto mode using the keypad for the furnace just scroll through till you see auto and then the ac wont run.

Bob & Carol
Washington St
2017 352RL 2008 D0dge 3500 DRW crew cab 4x4 LB 6,7L

[masterdrago]

I think the options are furnace, cool and heat pump

[rohrmann]

There is a separate fan switch function that will give you AUTO, LO, MED, and HI. You press the fan button multiple times until the display shows AUTO, and this will stop the fan in the A/C unit from running when in HEAT mode.

[mtlakejim]

Glad we have this site and there are some helpful folks out there. It took me a while to figure out the combinations on the new style thermostats as well.

[masterdrago]

Okay, thanks for the pointers. Here's the drill...
The mode button is capacitive so only just simple contact with it will change it. When off the display is blank. 1st contact will display a blank screen except "OFF" will show in the bottom right corner. Multiple contacts will cycle the display through "FAN" and a speed setting with a small degree sign in the top right corner. THEN, to toggle through the different fan settings (high, low, auto, etc) one must then use the triangle "buttons" on the right. This is the part I was missing. I was simply repeatedly touching the "MODE" icon on the left. So it was toggling through "COOL", "HEAT PUMP", and "FURNACE". I clearly did not know to use the icons on the right except to change the temperature. Lesson learned and thanks to all who responded with help. Sometimes I feel like a moron ;=]

[AZ Traveler]

Not a moron, just someone dealing with a thermostat which could be more intuitive. The lessons learned here make the forum invaluable.

[Golfmedik]

Originally Posted by AZ Traveler

Not a moron, just someone dealing with a thermostat which could be more intuitive. The lessons learned here make the forum invaluable.

Agree completely!

[mtlakejim]

Originally Posted by AZ Traveler

Not a moron, just someone dealing with a thermostat which could be more intuitive. The lessons learned here make the forum invaluable.

AMEN!

[DQDick]

Don't worry at all, that's what this forum is for. And by the way, you should see some of the early questions and problems us "old timers" posted when we were just starting out.