Furnace wiring issue


I replaced my Dometic AC unit with a Coleman AC unit. I also replace the thermostat with a Coleman. I created a wiring diagram before disconnecting anything because I saw a difference in wire coloring. After the swap I tested the AC unit and it worked great. I failed to test the furnace at that time (June in Arizona). I know is was dumb on my part.

I have since discovered that the furnace is not operating. I have also misplaced the wiring diagram I created. What I have discovered is the white wire from the thermostat is not connected to anything. There are also two wires (one white and one white/yellow) going to the furnace not connected to anything. The two wires going to the furnace connect to blue wires at the furnace.

Does anyone have a wiring diagram for the HVAC system in a 2011 Big Country TS3450? This is probably a generic wiring diagram. Which wires get connected to each other or do all get connected together? I am asking before I experiment and blow something up.



Well-known member
The furnace control was in the old ac unit. The Tstat sent power to a relay in the ac unit to power the furnace. You should now be able to wire the furnace direct. I don't know the specifics without research. The paperwork from the thermostat may have some clue for wiring or check the "Tools" tab for possible wiring schematics.


Well-known member
is the furnace and AC unit separate from each other, or combined?.... if combined, if the AC works, so should the furnace..... if they are fully separate units, the furnace Tstat wires are non polarized, and should connect either way on the back of the Tstat, regardless of color (ie: (2) blue Tstat wires at furnace, with an extension wire attached to reach the Tstat)

the Tstat should be marked in some manner that tells what terminals they connect to.....