Furnance Runs and Lights But only Cold Air .

[elkrott]

Friend has 2011 Montana not sure of model.
Furnance was never used.
Furnance lights exhaust is very hot but it only blows cold air through
registers.
Only one zone control set to 1 zone.
Unit has two ACs one installed by dealer so only 1 zone shows on controls.
Any help greatly appreciated.

[Mover480]

Make sure the fan is set on auto, not high or low.

[elkrott]

Just found out hes also having problems with furnance lighting and staying lite. Knowing this I think thats his problem.

[Old-Biscuit]

IF something was clogged furnace would trip from over heating or not light off due to lack of proper air flow.

They should be able to check ducts being connected to furnace....just need to look at backside of furnace.

How long have they let it run......takes a couple minutes before warm air comes out of floor registers.

Cold air will flow first (purge cycle) before gas flame will light off then after t-stat set point has been reached the gas flame goes off and blower continues to run for cool down cycle of burner chamber.

Cold air then warm air then cool air......normal function.

[elkrott]

They bought it brand new. Have sneaking suspicion that vents were never installed correctly at factory. They never used the furnace until a few days ago. Or maybe something is clogged.

[Terryallan]

Yes. IF the air you say is cold. Is coming out of the ceiling. You need to turn OFF the AC fan. Your heat will come out of the floor vents.

[Old-Biscuit]

If it's blowing hot exhaust then it is blowing warm heated air into the rig via the floor registers..........unless the ducts are not properly connected to the furnace discharge plenum.

Let it run...

[2-MTnesters]

The zone setting is only for the air conditioner. Have them check the floor vent in the bedroom by the bed. It will be much warmer than the other vents. Usually the vents in the kitchen and living room area won't be as warm since the run is much longer. The furnace in my 2010 Montana is located between my kitchen and bedroom slide, that's why the bedroom vent will be warmer. Also it will take a little while for the air in the other vents to heat up. Hope this helps. Tim