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Furnace doesn’t work

stew47
Explorer
Explorer
I should say furnace works if I jump the two thermostat wires. So we bought a 2007 Georgetown 37 xl and on the way home we tried to run the furnace. Swear they ran it for our demo but maybe not. When I got home I got to the wiring, jumped it and it started. I checked for voltage at the thermostat and nothing had voltage. Any thoughts? It’s a suburban 42.
10 REPLIES 10

DFord
Explorer
Explorer
dougrainer wrote:
stew47 wrote:
Ac doesn’t run


Then your problem is probably in the Wall tstat upper AC control board area. THIS controls both the AC and the furnace. Doug


Doug knows what he's talking about. The problem is the upper AC control board.
Don Ford
2004 Safari Trek 31SBD (F53/V10 20,500GVW)
'09 HHR 2LT or '97 Aerostar MiniVan (Remco driveshaft disconnect) for Towed vehicles
BlueOx Aventa II Towbar - ReadyBrake Inertia Brake System

stew47
Explorer
Explorer
No 12 volt from coach to ac. Fuse is good from power distribution box/ fuse panel.

dougrainer
Nomad
Nomad
stew47 wrote:
Ac doesn’t run


Then your problem is probably in the Wall tstat upper AC control board area. THIS controls both the AC and the furnace. Doug

stew47
Explorer
Explorer
Ac doesn’t run

dougrainer
Nomad
Nomad
Does the roof AC run? Doug

wa8yxm
Explorer III
Explorer III
What type of Thermostat. Many T-Stats today are digital electronic and have an internal battery. if dead no joy

My RV from factory used one of the A/C's to control the furnace (Front one) when I replaced the A/C I had to put in an new furenace stat

I got a 20 dollar mechnical mercury free (This is improtant) from Ace Hardware and a toggle switch and an LED indicator

Of the two, normally blue, wires one has 12 volt on it. this goes to the toggle (Which is mnounted beside the T-Stat I choose a rocker type) the other lead of the switch goes to the POSITIVE lead on the Led an the T-Stat
The other T-Stat lead to the other blue wire
The negative LED to Ground (it is a 12 volt LED indicator assembly)

Switch off = Furnace off
Switch on = LED on T-stat controls furnace
LED blinking (Slowly)( or dim = problem with wiring back at furnace
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times

stew47
Explorer
Explorer
I jumped the wires at the furnace. I have dometic ac and I have dometic slide type thermostat.

DrewE
Explorer
Explorer
DFord wrote:
Where did you jump the wires? At the furnace or at the thermostat. The only thing the thermostat is capable of doing is closing the circuit you say you're jumping. If you jump the wires at the furnace and it works but when you jump them at the thermostat it doesn't, you've got a bad wire between those two points.


Sometimes the air conditioner control box/board is also involved as a middleman between the thermostat and the furnace. If it's not getting 12V power or something it might not communicate betwixt the two. (On mine, there's definitely a relay on the air conditioner control board that is controlled by the thermostat and in turn controls the furnace. It's a Dometic air conditioner, originally with one of their slide rule style thermostats but since upgraded to a generic battery-powered digital one.)

DFord
Explorer
Explorer
Where did you jump the wires? At the furnace or at the thermostat. The only thing the thermostat is capable of doing is closing the circuit you say you're jumping. If you jump the wires at the furnace and it works but when you jump them at the thermostat it doesn't, you've got a bad wire between those two points.
Don Ford
2004 Safari Trek 31SBD (F53/V10 20,500GVW)
'09 HHR 2LT or '97 Aerostar MiniVan (Remco driveshaft disconnect) for Towed vehicles
BlueOx Aventa II Towbar - ReadyBrake Inertia Brake System

wnjj
Explorer II
Explorer II
Digital thermostat? Check for a blown fuse in the 12V load center. Make sure the thermostat doesn’t operate off it’s own battery.