New member, furnace won’t light

[Lbatz5706]

Hi all! Thanks for letting us join. We got a 2017 passport ultra light this past May that we live in full time. We used the furnace a couple times in May. We had an electric line 30 amp installed in June because we are on my daughters property and hooked up to her electric, water and septic. Now it’s October and getting cold at night. We went to use the furnace and you can smell the propane and hear a click but the furnace won’t ignite. Only cold air blows out. Any suggestions? Thank you!

[flybouy]

Are you smelling propane inside? There should be no way for propane to enter the living area inside the camper. The cold air is the furnace going thru it's fail to ignite and purge stages. Did the furnace work in May? This is strill September by the way but you could use a ceramic heater until this get's resolved. How mechanically inclined are you? Do you feel comfortable working on a propane appliance.
And welcome to the forum!

[Lbatz5706]

Hi! Thanks for replying! The furnace worked in May. The propane smell is outside by the furnace vent, when I try to light it, I smell it. We are using a small heater for early am chills. I’m comfortable working on propane appliance and am mechanically inclined. I did call an RV service tech to hopefully come out and see what’s wrong but some of them are booked into November!

[travelin texans]

Check for insects building nest in the burner tubes if it hasn't been used since May, this is a common issue.

[flybouy]

When outside do hear a "clicking" sound? If you then check the spark. The fact that you smell gas tells me the gas valve is working. As stated above spiders and other bugs are attracted to the smell and can nest blocking the orifice. Clean with an old toothbrush, check the electrode gap. If you don't hear that "clicking" noise check and make sure all wires are connected on the control board and the electrodes, with the unit off of course.

[chuckster57]

I’m betting on a mud nest on the burner.

[skids]

There is a "sail switch" that confirms that there is airflow out the exhaust. Never had an issue with it, so I wouldn't know if you could smell gas in event of it failing.

[chuckster57]

Originally Posted by skids

There is a "sail switch" that confirms that there is airflow out the exhaust. Never had an issue with it, so I wouldn't know if you could smell gas in event of it failing.

There is a series of “events” that take place before the furnace will light. If the sail switch fails, it won’t open the gas valve or apply spark (click).

If memory is operating in a proper manner it goes something like this:

Thermostat is turned up and heat is asked for. At that point the control board starts the “wheels” in motion. There is two separate fans (squirrel cages) that spin. Voltage goes from the board to a “limit” switch making sure the plenum isn’t too hot. Then to the sail switch to make sure there is enough air flow. At that point, voltage returns to the board and the gas valve opens and the igniter sparks. If those conditions don’t exist the furnace shuts down.

In normal operation once the “set temp” is reached, the board shuts the gas valve and goes into “cool down” mode, running the fans long enough to cool off the plenum.

I’ve seen the OP’s condition a few times and a mud nest is about the only condition that will allow gas to flow and igniter to spark but no heat (flame).