Furnace runs but will not ignite

Happened to mine right after we bought it. If you can smell propane, and hear it clicking, it may just be dust or better yet, rust from the inside of the unit itself. The paint on the inside of them is very cheap and when going through the heat cycles, it comes off creating a 'dust' on the inside that stops the ignition. All the tech did to ours was take it out, remover the cover and blow it out with an air finger. I was totally shocked at how much dust came out of it. It has worked great since. Just another opinion.

our camper's furnace has performed flawlessly since '05 .... we are currently in Texas where it has been used many times .... I was very surprised a few days ago it didn't light .... standing beside the outside exhaust port I heard the fan cut on, got a faint whiff of propane, heard a spark and what sounded like a faint pop .... as noted after failing to light after 4 attempts it would cut off .... the majority of the working components in our furnace can be accessed by opening the outer cover and then moving a shield .... with the cover removed we tried it again and the same process followed .... believing it had to be a propane issue I tapped the heater's valve that controls the flow of propane several times .... turned it on again and this time it fired right up .... it has continued to work for the last 3 nights .... it appears the valve was stuck .... even though it is working, it will be replaced when we get back home

Jim

Same thing happened to mine, it was a bad circuit board.

I had this same thing happen earlier this year. Furnace would light for a second or two, three tries, then lock out.

After getting back home I decided I would start the troubleshooting. First thing, switched tanks, all worked fine. A combination of a low, but not empty, tank and cool temps must have been the cause.

gordypig wrote:
A lot of answers here but none are correct. Put your nose to the furnace exhaust as its trying to ignite and determine if u smell propane, if not ur gas valve isn't opening, replace valve, or a mud dauber has nested in ur chamber or burner bar.Last scenario is you have a defective Chinese gas regulator

Care to expand on what is not correct?

IMHO your advise is wrong....you just don't start throwing parts at it

A lot of answers here but none are correct. Put your nose to the furnace exhaust as its trying to ignite and determine if u smell propane, if not ur gas valve isn't opening, replace valve, or a mud dauber has nested in ur chamber or burner bar.Last scenario is you have a defective Chinese gas regulator

btd35 wrote:
If you are hearing it click to ignite, then it is not the sail switch as the switch locks out the ignition and you will not hear a click. Most likely problem is the ignitor itself, the gas valve coil, or your gas supply has a problem.

Correct......sail switch has to make up otherwise no power to control board for ignitor.
Ignitor is clicking so there is power to board.....and to gas valve (power goes to both at same time)

3 attempts to light off and prove flame then lock-put.

Sounds like it just isn't getting gas.
Turn on stove top burners (high---all of them) and check how the flame looks on them. Are they all the same....strong blue flame/same height?

Then retry furnace again....gas flow may have failed during night (frozen reg./empty tank etc.)

Verify to have propane flow before tearing into furnace.
Good stove top burners and furnace still locking out (after a couple of attempts by resetting t-stat).
Then you will need to dig into furnace and check for voltage at gas valve (during ignition trail), check for gas orifice blockage/burner blockage etc.

Post back......

It sounds like an out of propane situation. So check your tanks to make sure you didnt already burn through it all. Check your tanks to make sure both are on (had that happen on my way to FL, filled one tank forgot to turn it on, middle of the night no heat/changeover.)

Check your change over valve, and then if both tanks are full change over is happy, cycle the furnace and see if you hear flow in the regulator...it can freeze up as mentioned.

If you are hearing it click to ignite, then it is not the sail switch as the switch locks out the ignition and you will not hear a click. Most likely problem is the ignitor itself, the gas valve coil, or your gas supply has a problem.

Low gas tank. At night as the temp lowers, the gas vapor pressure decreases to a point it won't sustain the burner. If so, you will smell gas as it is trying to light.