Atwood Furnace Problems

[pomology]

I have a problem with the Atwood furnace on my 5th wheel (2019 Montana High Country )

I just bought the unit second-hand six months old from a private seller and have never used the furnace system before. (The person I bought it from never used the furnace either because they had free electricity at the RV park). When I turn up the thermostat and go outside, the furnace blower turns on, and the sparker clicks to ignite gas. I smell pretty strong gas exiting the exhaust pipe and actually hear the flame briefly ignite for ½ second or so, and feel a brief rush of hot air. Then the flame goes out. The sparker attempts to re-ignite, I feel a rush of heat for a ½ second, and then the flame goes out. This happens repeatedly over and over again until the unit finally times out and the red LED has the 3-blink pattern.

Things I've tried:

1) All the other propane appliances work. Stove works fine, gas water heater (which is right beside the furnace) also works perfectly.

2) Propane tanks are full.

Any ideas of what I should try next would be much appreciated!

Thank you!
Randy

[DFord]

The control board on your furnace tries three times to prove a flame and then goes into a lock-out mode. You'll have to reset the thermostat to recycle it. It's working correctly.

Mud-dubbers and spiders like to build their nests inside the furnace and block the proper flow of things. The screens you can get at RV supply stores do a great job keeping out the wasps but do nothing for the spiders.

You'll need to open up the furnace and make sure there's nothing blocking the flame tube. There's flame rod where the spark jumps from and it must be surround by the flame rod to keep the gas valve open.

[happy2rv]

Sounds like the flame sensor is not detecting the flame although I would expect it to stay lit longer than 1/2 second. Could be a bad sensor or bad/corroded connection. It could also be the control board.

I would also inspect for any obstructions / nests / varmints in the burner/exhaust assembly.