When furnace is turned on roof air fans come on

Just bought a 2011 Big Country 3250TS on Maiden voyage needed the heat. Turned on Dometic digital thermostat. Furnace came on and the roof air started blowing cold air into the living area and through the vents. Needless to say the heat in bedroom and bath was fine but in the kitchen living area it was cold with the cold air from air conditioner blowing on high. Never heard of roof air coming on with furnace is this normal with Heartland or is something wired wrong. this is a small thermostat mounted below the fantastic fan thermostat. It has a digital read on temp. and up and down arrow to set the temp and an on and off that has a light that lights, fan, cool, heat. HELP weather in New England turning cool at night
 

jbeletti

Well-known member
Just a guess, but I think it's an incorrect DIP switch setting outside in the AC under the shroud. I'd consider calling your dealer on Monday.

The thermostat you describe is the new one I've been seeing the last month or so on our new coaches, so I am thinking it's the new standard. That said, perhaps the logic control is now in the thermostat.

Let us know how this comes out for you.

Jim
 

jimtoo

Moderator
Hi Kenneth339,

Welcome to the Heartland Owners Forum and Family. We have a great bunch of people here with lots of information and all willing to share their knowledge if needed.

Kinda hard to keep warm with the a/c on,, huh... Until you can get it back to your dealer for service, I would turn off the breaker for the a/c. I am pretty sure the a/c is 120v and the furnace is 12v. So you should be able to keep the a/c off with the breaker. Most likely the thermostat is wired wrong or it is defective.

Meanwhile enjoy the forum,, and if you lived in South Texas ... you would need the A/C and not the furnace. :D

Jim M
 

billm

Member
Had the same problem with my new 3450. The factory told me that the fan setting for the AC needs to be set on automatic not low or high. That took care of the problem.
 
Billm

Thanks for the reply, my thermostat is apparently a new model, no auto switch, just on/off, up arrow and down arrow for temp. and a setting for heat, fan or air. Ken
 

billm

Member
Kenneth,
Mine is also the new style(digital) but when you press the mode switch to go from heat to AC the middle option is for the fan settings. When you choose the fan option it allows you to choose low,high or automatic. The fan option only applies to the AC and I found it strange that it caused the AC fan to come on with the furnace. The small booklet for the thermostat that came with my unit does show how to change the fan settings.
 
Called the dealer this morning and found out that what billm said was right on by pressing the on switch when you are in fan mode you press the up arrow to change the fan setting from Hi, Low, or Auto. You go to the auto mode or AU on the display and when you go to heat for those chilly nights the furnace comes on but the AC does not come on. Thanks for all of you help with the posts you sent me. Being a newbe to 5th wheels will be a challange, 35 years is class C and A's. Thanks again. Ken
 
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