Atwood Furnace Problems

pomology wrote:
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