A/C running with heat?

[FiremanBill]

Hey all, we went out recently and were using our electric heat but it got really cold one night so I fired up the furnace. Turned the Dometic thermostat to heat and both the a/c unit and the furnace came on. Could not get the A/C off without cutting off the breaker for it. Furnace ran fine but would not cut off once the rig had warmed up.

I'm guessing the thermostat is bad... We have the one in the picture. Anyone else had this issue and did replacing the thermostat fix it?

Thanks

 

[Lynn1130]

Check your thermostat to be sure the fan is set to AUTO. If it is not the air will come on with the heat. See Related Topics at the bottom of the page. There are a number of threads on this problem.

 

[FiremanBill]

I did a search before posting but did not find anything, now I see them pop up as related... At least I tried.

Will check that this evening. Thanks

 

[For20hunter]

Your thermostat is fine. It is like what the other person said, your thermostat fan is set to low, medium or high instead of Auto. When it is on Low, Medium or High, this makes it so the fan on the AC unit(s) come on anytime the Furnace or AC is turned on.

Rod

 

[SLO]

X3 on setting fan to auto. I found out the hard way too.


Sent from my iPad using Tapatalk

 

[FiremanBill]

Thanks all. I did not get to check it last night but will today. thanks for the kind responses.

 

[avvidclif]

When I have to run the furnace I like to run the AC fan on low to help circulate the heat. The AC doesn't come on, just the fan.