Furnace doesn't always light

Thanks for the follow up!...I had a similar problem on my Atwood 2 speed 15/22 and it ended up being the electrodes (behind the gas valve) needed gapping...They were at 1/4" and I squeezed them to about 1/8" and ALL was perfect again...Later I called Atwood Tech and they said that they should be set at 1/8"...

Nice to tie up a loose thread once in a while.

After several months of the furnace working / not working pretty much randomly, I finally isolated the problem to the wires on the gas valve. There are two red and two yellow (actually one connection each jumpered across). The connectors were a bit loose and when the furnace wouldn't light, I could get it to go by wiggling those connections. I finally got the connectors off and tightened up and back on with a pair of curved forceps.

Furnace working now. Case closed (I hope).

I haven't done anything to mine other than look for the high temp switch which I couldn't find.

64T

I did what I could, but the sail switch was not accessible without some disassembly which I did not know how to do. And as I'm about to cross the continent boondocking I need reliable heat. I'm going to try to figure out how to access the sail switch to clean it.

I blow out my furnace, fridge and water heater every year. Spiders love the scent of propane or maybe they get Hi not sure but they will spin webs in there. Found that out the hard way. Was in the mtns for 3 days with no hot water

Here's what my two problems solutions were. I just picked it up from the RV shop. The furnace sail switch had lint & debris on it which prevented it from reliably opening every time. They had to pull the fan cage to access it. They also cleaned the burner, checked the electrodes & blew out all. I had done some of that, but did not know where the sail switch was, so the $125 they charged me for that was OK.

The fridge freezing the food was because the wire for the thermostat was touching the canister of the cooling unit which can get hot. Once they move the wire they said it worked well. That also cost $125. Wish I had known about that.

Hope this helps others DIY to save that $121/hour min charge + shop supplies.

Is there any relationship between the Outside Air Temperature and when it works vs not working. If so, you may have a oil filled p-trap in the copper line to the furnace that will pass gas when warm but not when cold.

My 17 year old furnace starting acting up like yours last November. I'ld hear it clicking after the blower started & then nothing. It'ld try 3 times to light (clicking) and then the blower would just push cold air. This was while I was plugged into shore power. Sometimes it would light & run well. I have replaced the blower motor & ignitor (whatever it's called) the last 3-4 years.

I'm going to take it into the rv repair shop I go to in a week or two. I should have done this last Dec before storage, but the snow had started. Little did I know this would be the worst winter in decades.

I haven't done anything about this intermittent problem because it has been behaving itself for the last few weeks. The last few days though, it has been a bear.

One thing I did notice this morning that I wasn't sure of, is that the furnace doesn't even try to ignite when it gets in this stupid mode. When it decides to work, the igniter goes tick-tick-tick-tick (in about 1 second) and the furnace ignites immediately.

One thing I did not see mentioned.. If the fan starts and the propane valve opens (Indicating Thermostat and Sail switch are good) the ignition points are often a bit wider than spec,, I think on my RV they were 2x the specified spacing per the onwer's manual.. On the oil fired furnace in my parent's sticks and bricks 4x.. Re-setting the gap made a big difference.