no heat!

My Suburban furnace acted that way too. The cure was to clean the furnace, Crispy bugs can slow the airflow enough to prevent ignition. The sail switch is how the furnace knows it has enough airflow.

I hope you have it fixed. If voltage and LP pressure is good, I'd go to the board and jumper 12v to it. If that didn't work, I'd check the ignitor rod for alignment, damage and positioning. If that doesn't work... find an RV tech or drain the water and get a motel. You have my deepest sympathy! I worked there for nearly a year in the early 80s putting the AC in the Casper Star Tribune bldg. I also fixed my share of roof units in that town in the winter in the snow storms. Craig

Hopefully OP either got it working or stayed somewhere else with the temps as cold as they are there. Amanda, if you log on again let us know how you are. Some of us are concerned, -40 without heat is dangerous.

Unless OP is up on Casper Mtn. (8100') Casper is only 5200'

Been there many times and never a problem with furnace due to thin air

OP has a voltage/circuit problem or a bad circuit board.
Needs to do some checking with a digital meter

I had the same symptoms in a trailer I had a number of years ago. The problem only occurred when we camped above 6 or 7 thousand feet. The reduced air density at elevation resulted in the sail switch not being engaged, and not opening the propane valve. The blower fan would run for a few minutes and then shut off.

This should be simple to check. You can force the sail switch to close by just holding it. If the furnace lights off while holding the sail switch closed, you have found the problem. If the furnace doesn't light, then you need to look else where.

I identified my problem as the sail switch failing to completely close. My solution was to increase the area of the sail switch by folding some heavy duty aluminum foil around the sail to increase it's area.

Some systems are designed and developed to work well at or near sea level, and are not tested at 7 or 8 thousand feet.

CasperRVlivin wrote:
I don't know if this is the right forum to post in- but I'm living in casper this winter in my 5th wheel and this morning I woke up to no heat! my furnace wouldn't come on when I turned the heat up. I toggled the "furnace"switch to "off" and back yo furnace and it came on, but the air coming out didn't feel hot. after about 5 minutes it turns off and won't come back on again unless I toggle the switch again. help! I'm going to freeze to death! my propane is on and working because I can light the stove.

This happened to me the other Day right after I had my LP Tank filled up. The Furnace worked fine the next Day. I suspect I had some Moisture Condensation in the Line.

Same symptoms here. It was a bad control board.

Mmwtdh wrote:
I had the same symptoms with mine and the control board of the furnace was bad....

Hi,

It may be cold enough that there is an insufficient vaporization rate to support the demand the furnace places on the propane supply. Adding a heating pad may help.

It is also possible that the converter can't keep the battery charged enough for the fan speed to activate the sail switch. If it is a modern converter--try it with the battery disconnect switch to store (off).

OP stated he has propane and can light the stove.
Hopefully he hasn't frozen

Furnace fan is blowing but no ignition/main flame

So.......
Check battery voltage....furnace fan can run with low voltage but can't blow enough air to move/make up sail switch.
Battery voltage needs to be at least 12.4V DC

IF good battery voltage
Check for obstructions/blockage at intake/exhaust
Check that sail switch moves freely....check for voltage at/thru sail switch contacts and to circuit board (has to go thru high limit switch which is hard to check without removing furnace)
IF good voltage then circuit board is not sending voltage to spark electrode (no clicking)

Dayle1 wrote:
There is a 'sail switch' in the intake air flow path and if the intake is blocked by snow or otherwise, then there is insufficient air for combustion and the valve that controls the flow of propane to the furnace will not open.

This just happened to us with a "regular" furnace at work - and the sign that the switch had been tripped is that the blower runs constantly but there's no heat.