Furnace not lighting

[jabrabu]

I have a Chateau 31E. When turning on the heater the blower comes on for a minute, but then it shuts off without igniting. The igniter isn't clicking and there is no gas smell.


There is plenty of propane and the gas stove lights just fine, so propane supply is not the problem.



From what I've found online, the most likely problem is the sail switch. I removed the sail switch and cleaned it, but it didn't fix the problem. I also jumpered out the sail switch and the same problem happens. So it doesn't seem like the sail switch is the problem.


What's the next most likely problem, and how do I continue to troubleshoot? It could be the circuit board, or high limit switch, or maybe the igniter, I don't know. Any suggestions?

[16ACE27]

Fire the parts cannon at the circuit board as the next likely suspect. But a cheaper shot would be the igniter as that could cause your symptom as well.

Check your furnace's user manual for a troubleshooting chart.

[OldWEB]

I agree, igniter should spark and gas valve open after the purge cycle, appears to do neither. Any blinking light on circuit board?
Voltage check on the gas valve would determine if the board is telling it to open or not.
Make/Model of furnace would help in our guessing.

[jabrabu]

The problem ended up being the high temp limit switch. From what I've read, the most common problems are the sail switch and the high temp limit switch. I started by cleaning the sail switch, which didn't fix it. Then I replaced the sail switch since it is easy to do, but that didn't fix it either. So then I replaced the high limit switch and that fixed it.


You can test that high temp switch with an ohmmeter. It should have continuity between the terminals. It is before the circuit board in the circuitry, so the circuit board won't even get power if this switch is bad.



I made the mistake of completely removing the heater unit based on the youtube videos I watched. In those videos the high limit switch/sensor is on the back of the furnace. But after I removed mine I realized that mine is accessible from the front. It's just hidden behind the ignitor/gas valve assembly. So I disconnected the electrical, the propane connection, and all the ducting and removed the unit for nothing. However, the screws holding the high limit switch wouldn't budge and got stripped out, so I had to turn them with pliers from the back side, so maybe it was necessary to remove it after all.

[10scDust]

Thank for posting your follow through to a remedy.

[FullerMX]

Originally Posted by jabrabu

The problem ended up being the high temp limit switch. From what I've read, the most common problems are the sail switch and the high temp limit switch. I started by cleaning the sail switch, which didn't fix it. Then I replaced the sail switch since it is easy to do, but that didn't fix it either. So then I replaced the high limit switch and that fixed it.


You can test that high temp switch with an ohmmeter. It should have continuity between the terminals. It is before the circuit board in the circuitry, so the circuit board won't even get power if this switch is bad.



I made the mistake of completely removing the heater unit based on the youtube videos I watched. In those videos the high limit switch/sensor is on the back of the furnace. But after I removed mine I realized that mine is accessible from the front. It's just hidden behind the ignitor/gas valve assembly. So I disconnected the electrical, the propane connection, and all the ducting and removed the unit for nothing. However, the screws holding the high limit switch wouldn't budge and got stripped out, so I had to turn them with pliers from the back side, so maybe it was necessary to remove it after all.

Thanks for the follow-up. I can confirm the exact same scenario happened on my 31W. No explanation as to WHY the limit switch failed, but replacement solved the issue. Did find later that the wire connection came loose and needed to be re-done as well. Anyway, thanks for writing originally and posting what you found.

[DogLovers]

Your post is dated March 6th I did not even get the meail from Thor Forums until this morning Marcg 18th. Wonder why it takes them so long to forward these questions.

[Jimbo56]

Originally Posted by DogLovers

Your post is dated March 6th I did not even get the meail from Thor Forums until this morning Marcg 18th. Wonder why it takes them so long to forward these questions.

Usually won’t get an immediate email unless you posted on same thread. That’s been my experience.

[16ACE27]

Originally Posted by DogLovers

Your post is dated March 6th I did not even get the meail from Thor Forums until this morning Marcg 18th. Wonder why it takes them so long to forward these questions.

Forward what questions? You are not subscribed to this thread so you would not be notified of new posts in this thread.

If the email you are talking about is the Newsletter, it only comes out once per week and contains only selected threads, not all of them.

[Falls]

I have to replace my igniter every two years. I would try that first. They're cheap.