Duo Therm 65900-001 sparking but not lighting?

[thetundrawolf]

Hi, I have an older trailer with a Duo Therm 65900-001 furnace, it's getting propane fine, and 120v, when I connect the thermostat wires the fan comes on, and it sparks, I hear the solenoids in the propane valve click on, and I see it sparking in the glass window, but it never ignites. Any ideas on why it's not igniting?

[Chris_Bryant]

That’s an old furnace, most likely needs cleaning. If it is sparking the sail and limit switches are good.

[StirCrazy]

i had the same issue with my camperi just bought. a good air gun and 10 min of blowing out the combustion side, it now works perfectly.

Steve

[Roger10378]

Probably a spider web in the burner tube. You wouldn't hear the gas valve if the sail switch was not working.

[laknox]

thetundrawolf wrote:
Hi, I have an older trailer with a Duo Therm 65900-001 furnace, it's getting propane fine, and 120v, when I connect the thermostat wires the fan comes on, and it sparks, I hear the solenoids in the propane valve click on, and I see it sparking in the glass window, but it never ignites. Any ideas on why it's not igniting?

Might be a bad sail switch.

Lyle