Originally Posted by J Birder
I don't know that furnace. The sail switch will be a fairly large paddle connected to a switch. It is intended to prevent the furnace from operating if there isn't air flowing into the ducts. It will be located very near where the air duct connects to the furnace.
The wires for the sail switch on an Atwood come out the top or side, but the switch itself is under the outside blower cover.
I want to know how he knows the gas is coming on? Can you smell it? Hear it?
If the gas valve is coming on, letting gas through, and you can hear the ignition click, you should get a couple second poof of flame. The gas valve will not stay on more than a second or two if it does not sense flame from the igniter electrode.
I had one once that would go through the entire cycle, open the gas valve, and didn't ignite until the 3rd spark, Shot about a 3 foot flame out of the exhaust, then went out.
I had another one that would not run on battery power, but if connected to shore power and full 13+ volts would run fine. Finally tore into it and 2 fins on the fan (plastic) were broke off. Needed to run full power to trip the sail switch. Replaced with steel fan. No more problems.
But from the sounds of it, since it was working, then suddenly quit, I would put my money on the time delay relay.
Also, pull the burner out and check condition. They tend to burn through and then the flame is not consistent and even.
And while the burner is out, pull the igniter, shut the LP off at the tank and try to fire it. See if you get a spark. The igniter is very sensitive to the gap. 1/8 inch, no more, no less. If you get a spark, clean both probes with steel wool and make sure the gap is right.