- Find the furnace fuse, and ensure it is good.
- Check for 12V on each wire (to ground)
- Mark each wire that has 12V.
- Remove the furnace fuse.
- Check voltage on those wires that had 12V.
- The one that had 12V with the fuse in, and doesn’t have 12V with the fuse out is the 12V feed to the furnace.
RV furnaces run on 12 volt only.
Maybe show a photo of the furnace and I could help you.
Atwood or Suburban and model #
Wow, what a mess…
To add to what NEHOG said.
A furnace only has 4 wires:
- Ground – it’s likely any of the stranded thicker white wires will work
- 12V+ Power – most likely the same thickness as the white stranded wires, but a different color, could be the blue, yellow or black? Like NEHOG said, check the Furnace fuse if you aren’t getting 12v+ If they are ALL 12V+ see which one stops working when the Furnace Fuse is pulled.
- A pair of (usually thinner) wires from the thermostat, to determine those, disconnect the thermostat from the wall and see what the wires coming out of it look like and find the matching end in that mess. You could also see if they have continuity across both when thermostat is turned on high and lose continuity when thermostat is turned off.
Your new furnace will have 3-4 wires that connect like:
- Ground to Ground
- 12V+ to 12V+ and one of the thermostat wires
- on/off to remaining thermostat wire
Good luck!
Are you sure that’s where the furnace goes? I don’t see a hole for the exhaust….
Can you check your panel for which wires run to that breaker?
Source: I’ve been told that the wires I need to hook up my furnace are in this mess, anyone have a clue?
