furnace blower motor when thermostat switched to on

[not_enuf_toys]

First, thanks for taking a look at this. I appreciate any help you can give me.

2007 forest river Salem 30QBSS
Suburban furnace
Dometic AC

Everything worked great at first. ac, furnace, auto, on, hi/low speeds.

the issue is, when I used to switch the thermostat from auto to on, the blower motor in the furnace used to kick on (when just on 12v). Now (still on 12v) when I click the switch from auto to on, the ac makes a one time click noise and the blower in the furnace never turns on. when plugged into 110, and switch from auto to on, the ac blower kicks on.

have tried a new thermostat and still the same results. I am thinking something goofy has happened with the furnace or analog controls but not certain.

Any thoughts? ideas? things to try?

[Lazydude]

The only way to tell if the curcuit board is bad is to replace it, so you might want to take it to a RV repair place and let them do it. It cost me 350 bucks cdn to have mine fixed.

[Lazydude]

It's the circuit board inside the furnace.

[not_enuf_toys]

Lazydude wrote:
I had the exact same thing happen to me last year and it turned out to be a stuck relay on the furnace board. I could bang on the furance to get it to start some times but after awhile even that did'nt work. They had to change out the whole board to fix it.

failure of sounding dumb - "on the furnace board"? is that physically on the furnace motor? I can take a look at that in the next day or two when I am back at the camper

[Lazydude]

I had the exact same thing happen to me last year and it turned out to be a stuck relay on the furnace board. I could bang on the furance to get it to start some times but after awhile even that did'nt work. They had to change out the whole board to fix it.

[VTR]

I had a thermostat and furnace issue this last trip, Following thread--