No Furnace power Atwood 8535

[Sooptime]

I think I found the culprit. Chewed 12V red wire way back in the recess under the shower behind the panels, inaccessible from the furnace space. This wire feeds to the reset switch on the furnace. I'll let you know if that was it when I manage to splice it all up. Gonna be a royal PITA getting in there.

 

[Carl n Susan]

You gotta love them mice.

 

[Sooptime]

Well, I now have power to the furnace board, but no blower fan and no V at the blower terminal or 6 pin connector. The RV Repair Woman advises that it is the control board if no V at the blower or 6 pin power. Doesn't make sense since I just replaced the control board at the outset of this. I also do not have power at the multi-pin connector on the board for the Tstat and no power at the Tstat on the wall.
Possible I have two bad boards I suppose.

I appreciate all the advice. It has helped.

 

[Sooptime]

Tstat can be eliminated by simply connecting the two blue singal wires at the furnace control board .. if furnace does not run Tstat is not the issue... if furnace DOES run there is an issue with Tsat or the AC control board is not completing the circuit on its signal wires to the furnace control board

So, I have 13.5V at the pwr terminal and no V anywhere else. No 12V at the blower terminal or 6 pin connector.

I jumped the two blue wires before they enter the furnace and the blower came on and igniter tried to fire it up a few times. The new thermostat in the rig has no power to it either. I tried a replacement RJ11 between the ceiling AC and thermostat to eliminate any low voltage break in the existing wiring between AC and Tstat. Still no power to the Tstat so I suppose it is somewhere in the mass of wires between the furnace and AC.

I fixed the chewed red pwr wire feeding the furnace and it gave me back my 12+V to the board. Just no 12V past that. No 12V at the AC or Tstat pins on the board.

I appreciate your help. Heading to town to get a basic analog Tstat and some wire and use that until I can locate the exact issue between the furnace and AC. At least I know it isn't at the furnace components.

 

[Sooptime]

So, I think this is the final outcome and note on this. The furnace is blowing hot now. I opened the AC box in the ceiling. A 3A fuse was blown. After that, still no furnace, so checked the thermostat feed wires. The thermostat was powering but no furnace mode. Checked the redhead splices in the RJ11 to the thermostat and although the splice appears tight, the yellow wire is intermittent.

Thank you all for all of the suggestions and advice. Thanks Chuck for the schematic and the knowledge. It's great having heat finally. At the center of it was a chewed red power wire way down under my shower, behind the panels. Live and learn.