Furnace

[Jamric]

2022 3121 rl no heat circuit board checked good , sail switch is good tries 3 times to light then locks out! Could igniter be bad can smell propane when gas valve opens?

[MandK]

Yes. Same symptoms that we had and it was the igniter. I could hear the igniter rapidly firing just after hearing the gas valve open but it would not light. I sanded, checked the gap and cleaned the tips reinstalled it and it then it worked intermittently. Ended up just buying a new one from Amazon.

[Jamric]

Originally Posted by MandK

Yes. Same symptoms that we had and it was the igniter. I could hear the igniter rapidly firing just after hearing the gas valve open but it would not light. I sanded, checked the gap and cleaned the tips reinstalled it and it then it worked intermittently. Ended up just buying a new one from Amazon.

can you get igniter out without pulling the furnace out?

[jsb5717]

The igniter is integral to the control board. If you're hearing the igniter clicking then it's working. Are you thinking it might the the electrode? It's possible. If the igniter is clicking and you're smelling propane then the last step is ignition. Have you pulled out the burner assembly to check those components? Our diffuser rusted over and needed replacing. Worth checking that and the electrode gap.

[MandK]

I guess I should have said electrode. Yes when you pull the burner assy out, the electrode comes with it and a single sheet metal screw holds the electrode On.
Fwiw, another member here has stated in the past that he had a similar problem and the screw had a little corrosion on it and wasn’t making good contact with the chassis of the burner. That screw acts as the ground for the igniter. But as Jeff said, you should be able to hear the igniter on the circuit board firing right after you hear the click of the gas valve opening.

[Jamric]

Pulled burner assembly, cleaned out had a few bugs in it , pulled orifice and cleaned, sail switch is good new control board doing the same thing light and go out does it 3 times

[jsb5717]

Ah, so it’s actually igniting before it fails? That’s different. There are a few things that could be.

Propane valve - it’s possible it’s not putting through enough propane
Propane regulator - same issue. I’ve seen both of these fail on different furnaces
Limit Switch - Easiest and cheapest to try. You can just jump/bypass this switch and see if the furnace works.

Without the proper testing equipment it’s difficult to know for sure which component is failing. I have a replacement component for most everything on my furnace so I don’t get stuck without heat and it’s easier to troubleshoot.

[MandK]

If I remember right, I think it could still be the electrode. The electrode also acts as a flame sensor. If it’s not sensing a flame, it shuts off the gas.
But you mentioned earlier that you could smell propane while trying to get it to light, that would make me think it’s not lighting in the first place.

[Jamric]

Thinking it’s isn’t propane regulator as other propane components work fine just a guess ! Going to try limit switch !

[Jamric]

I’ve got it to light but won’t stay lit, runs 2-5 seconds on cuts out!

[ChuckS]

Originally Posted by Jamric

Thinking it’s isn’t propane regulator as other propane components work fine just a guess ! Going to try limit switch !

Just measure across the limit switch ( with the two wires removed ) using multimeter set to ohms.. should read continuity .l if yes you are wasting money on new limit switch

This switch opens up when it gets too hot and shuts down the furnace

[MandK]

Yeah, not sure if it’s the limit switch. My limit switch is in series with the sail switch, if that circuit was interrupted it would not light at all. It would shut down earlier in the sequence of events.

[jsb5717]

Originally Posted by MandK

Yeah, not sure if it’s the limit switch. My limit switch is in series with the sail switch, if that circuit was interrupted it would not light at all. It would shut down earlier in the sequence of events.

But you can easily test it by the ohm test Chuck suggested or by jumping the 2 blue wires connected to it, essentially bypassing it and keeping the circuit closed. If the furnace runs normally then you can be pretty sure it’s a faulty limit switch. If not, then move on to a different component.

Don’t continue to run the furnace with the limit switch bypassed, though. If faulty, replace immediately.

[Jamric]

Just checked limit switch , it was bad , thanks for all the info!

[MandK]

Glad you got it. I learned something today too!

[Jamric]

Tried furnace this morning after getting it to work with bypassing heat limit switch, now the fan just runs and no ignition! Sail switch or what?

[Jamric]

Sail switch checks good even jumped it, opens gas valve can smell it ! Control board or igniter???

[MandK]

Maybe should have posted this on the thread you already had started so potential helpers could see what has already been discussed to better help you out. Good luck with it, furnace issues can be frustrating.

[Carl n Susan]

Originally Posted by MandK

...Maybe should have posted this on the thread you already had started so potential helpers could see what has already been discussed to better help you out. ..

As suggested, the new Thread Posts have been incorporated into the original discussion as the problem continues.

[GreG L.]

I had a similar issue, it turned out to be the black 15 amp fuse that trips and resets itself, mine was tripping soon after ignition and than resetting right away. Swapping it with a regular blue 15 amp fuse solved the issue.