The old furnace and a/c no power

[bschelle]

I have a 2007 Coachmen 28DSB. The furnace and air do not work. I have checked all of the visible fuses and circuit breakers and all are good(checked with my meter). I do not have any power to the Dometic thermostat. The red wire has no voltage. There is not any fuses behind the thermostat. I pulled the wires and nothing there. I connected a 12v hot lead to the red terminal on the stat and nothing changes. I checked the red lead on the furnace and it does have power. Tried resetting the furnace with the reset switch and no change. I even replaced the thermostat for same results. I am running out of ideas. I need help!!!!!

 

[Gary RV_Wizard]

Both the furnace and the a/c have their own power wired in directly (12vdc for the furnace, 120vac for the a/c), but they both rely on a +12v signal from the thermostat to get them to do anything at all.  You should be able to apply 12v to the thermostat wire to the furnace and have it begin it light-up cycle.  I don't think that wire is typically red, though. What furnace make/model and what model of Dometic thermostat do you have?

Do yu have a single thermostat for furnace and a/c?  Typically the thermostat gets its 12v power from either furnace of a/c, but it varies with the set-up and the RV manufacturer.

 

[X-Roughneck]

I have a 2007 Coachmen 28DSB. The furnace and air do not work. I have checked all of the visible fuses and circuit breakers and all are good(checked with my meter). I do not have any power to the Dometic thermostat. The red wire has no voltage. There is not any fuses behind the thermostat. I pulled the wires and nothing there. I connected a 12v hot lead to the red terminal on the stat and nothing changes. I checked the red lead on the furnace and it does have power. Tried resetting the furnace with the reset switch and no change. I even replaced the thermostat for same results. I am running out of ideas. I need help!!!!!

Bschelle,

Hope you come back and take us down the road to repair with you. 

I can bet for sure this problem will be solved with electronic shared brain power.

The Classic Rockers of RV (Aerosmith's, Eagles, Ted Nugent the Motor City Madman) equivalent, they all hang out here and throw out a few daily tips to their masses of RV Followers.

I am surprised Henry Fate the Remote Troubleshooter has not chimed in.  ) ) )

You Electrical Nightmare will soon come to resolution / solution. 

Now I can tell you once that AC is fixed it still wont cool that thing so stay out of camping in real hot weather.  That is my tip for you.  ;D

JD

 

[bschelle]

Replced the power boards in the AC and furnace and all is good now!

 

[Lou Schneider]

Great! Thanks for sharing the result.