furnace and ac running together

hello. last week I hooked up our 2015 bighorn so the DW could campout in our driveway with her nieces. tomorrow is supposed to go below freezing. I unhooked the water and thought I would run the furnace at 40 so I wouldn't have to rewinterize. I turned on the furnace at the back thermostat and the back ac came on. first time using furnace. I turned off the back thermostat, and turned on the front one in the bedroom to see if the furnace only worked on one of them. front ac came on. turned that off. went to the back thermostat and turned it back on and listened to the ac while I thought about what I was doing wrong. then the furnace came on but the ac stayed on to. so I turned the breaker off for the back ac and the furnace stayed on. this is our first 5th wheel but third camper and this can't be right. at least it works but having to turn the breaker off on the ac makes me think something is wrong and that worries me when it has to do with anything propane. any thoughts would be helpful and also is the furnace set up to only one or both thermostats?

Put your thermostat on 'FAN' mode and put it in 'AU' (auto).

Then go back to the furnace mode.

This should solve your problem.

It is just a setting. You just need to go into the fan settings of the thermostat and change it from "Low" or "High", which it is obviously set to and change it to "Auto" which is "Au" on your thermostat.

Rod

For20hunter said:

It is just a setting. You just need to go into the fan settings of the thermostat and change it from "Low" or "High", which it is obviously set to and change it to "Auto" which is "Au" on your thermostat.

Rod

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I guess I had it backwards . . . just fixed my above post.

LOL! We knew what you meant, but unfortunately the OP might not have.

Rod

JohnD said:

I guess I had it backwards . . .

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thanks guys i'll try that when I get home tonight

Used my furnace for the first time and ran into the same issue. The solution posted worked like a charm! Thanks guys!

Oh my goodness. We're at the lake and it got cold last night. Same problem! I couldn't figure out why the AC would come on with the heat! Thank you- thank you- thank you! Such an easy fix!


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Had the same problem! First time turning on furnace in our new rig. This quick fix worked! THANK YOU!