8535 IV Atwood Hydro Flame furnace won't work

If the fan will not start and circuit from thermostat OK and 12 VDC to PC board, it is NOT a sail switch. The sail switch only comes into play AFTER the fan starts.

Agree with others, the PC board (or connection to it) is bad.

I would start by cleaning the contact area of the PC board and reinstalling the gang plugs using a good electric cleaner such as http://www.deoxit.com/

If that doesn't work, replace the PC board.

Yes we did have blinking light last week but nothing this week. Took board by 2 places (Camping World & Robert Handy Camping) to have board checked but neither could.

Power to board from 12V DC supply
Power to board via t-stat
Fan runs if jumpered

Last week you had blinking light????

Post from 10/22

Seeing as fan doesn't run unless jumpered..then 'Airflow' would be the issue

Process of elimination. Sail switch not stuck and fan doesn't run with power to circuit board............hummmmmmmmmmm
Bad circuit board :S

As said previously, it does appear likely to be a board failure then. Some RV shops can test them.

No lights blinking. Took all connectors off cleaned and replaced Got nothing

Just had the same problem. Had to replace the $15.00 Limit Switch behind (deeper in the shroud)the sail switch. Looks sort of like a quarter with a couple of wires.

rocmoc n AZ/Mexico

This was discussed on a couple of other threads over the last month;
May want to check them out.

Essentially, you probably have corrosion on one of the connectors; Open/remove
the outside panel and disconnect/reconnect all connectors;

Seems like a lot of people have the same problem

gerry

Moved from Forum Technical Support

Does the fan run? No, then the fan relay on circuit board has failed.
Dinosaur electronics makes a direct replacement.
Fan 50

Is there a light blinking on the board?