Furnace not lighting consistently

Jimblackjim

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Help!

I have a 2023 2670MK. We have been on the road for week and experiencing overnight temperatures in the mid to upper 20s. All has been good until last night when at 2AM I noticed that the furnace did not light.

Thinking I had run out of propane, I went outside and switched the lever to the second tank. It lit once on the new tank, then failed to light several times after. I put a known full tank on and had the same results.

The furnace lights on one of every 5-7 attempts.

Edit: I see a red LED that flashes three times indicating ignition lock-out.

Note that the stove lights with no problem.

Please share any thoughts on anything that I can check to see if I can get this working dependability again.

The furnace is Dometic Model DFMD30111.

Cross posted on Facebook
 
Last edited:
Help!

I have a 2023 2670MK. We have been on the road for week and experiencing overnight temperatures in the mid to upper 20s. All has been good until last night when at 2AM I noticed that the furnace did not light.

Thinking I had run out of propane, I went outside and switched the lever to the second tank. It lit once on the new tank, then failed to light several times after. I put a known full tank on and had the same results.

The furnace lights on one of every 5-7 attempts.

Please share any thoughts on anything that I can check to see if I can get this working dependability again.

The furnace is Dometic Model DFMD30111.

Cross posted on Facebook
Probably the regulator froze up.
If you can insulate it with a blanket etc when it is not frozen,it should work.
If it is already frozen, use a hair dryer on it first
 
Probably the regulator froze up.
If you can insulate it with a blanket etc when it is not frozen,it should work.
If it is already frozen, use a hair dryer on it first
Thanks for the reply. I forgot to mention that the stove works fine. Wouldn’t that indicate that the regulator is working properly?
 
Our furnace last year wasn't lighting properly and I would switch the thermostat to air as soon as the fan started I would switch it back to furnace and it would light right up.It would do that when the furnace hadn't been running for awhile. This year it has been fine.
 
Thanks for the reply. I forgot to mention that the stove works fine. Wouldn’t that indicate that the regulator is working properly?
Not really, as the stove top is not as pressure sensitive as the furnace.
 
Thanks for the reply.Yes I forgot to mention that the stove works fine. Wouldn’t that indicate that the regulator is working properly?
Thanks for the reply. I forgot to mention that the stove works fine. Wouldn’t that indicate that the regulator is working properly?
A frozen regulator is quite common, and easy/cheap to fix.
So exhaust that possibility first. Digging further into the furnace is a lot more work, and will cost more.
A stove is not nearly as fussy about propane pressure.
 
A frozen regulator is quite common, and easy/cheap to fix.
So exhaust that possibility first. Digging further into the furnace is a lot more work, and will cost more.
A stove is not nearly as fussy about propane pressure.
Thanks, again. I used the hair dryer on the regulator and the furnace did light up; not on the first click but on the second.

Since it has been lighting up every 5-10 tries anyway, I’m not ready to declare this as the fix, but I am hopeful.

I’ll update as the day progresses. Still below freezing, with sleet/snow here in Galveston.
 
UPDATE: Thanks to all of you who offered suggestions on how to solve my furnace issue.



As it turned out, the problem was the igniter. Details below.



The fact that it occurred just after I ran of propane appears to be a coincidence. That, plus the fact that the failure was intermittent made it difficult to nail down.



After trying everything I could think of, and to the extent I felt capable, I called a mobile tech. Steve came out in the sub freezing, windy weather and worked on it late in the day yesterday. We confirmed that the propane flow and pressure were good and the gas valve was working. He swapped out the sail switch and main control board confirming they were good. By then it was too dark and cold to continue.



Steve came back today. We tried a few more things. Since the furnace did light sometimes, we thought we fixed it several times only to have it fail again. Eventually he replaced the igniter. After that the burner lit immediately on the first click. Every time. So I’m pretty sure that the problem is solved.



Hopefully my saga will be of help to others.
 
UPDATE: Thanks to all of you who offered suggestions on how to solve my furnace issue.



As it turned out, the problem was the igniter. Details below.



The fact that it occurred just after I ran of propane appears to be a coincidence. That, plus the fact that the failure was intermittent made it difficult to nail down.



After trying everything I could think of, and to the extent I felt capable, I called a mobile tech. Steve came out in the sub freezing, windy weather and worked on it late in the day yesterday. We confirmed that the propane flow and pressure were good and the gas valve was working. He swapped out the sail switch and main control board confirming they were good. By then it was too dark and cold to continue.



Steve came back today. We tried a few more things. Since the furnace did light sometimes, we thought we fixed it several times only to have it fail again. Eventually he replaced the igniter. After that the burner lit immediately on the first click. Every time. So I’m pretty sure that the problem is solved.



Hopefully my saga will be of help to others.
I hate trying to fix an intermitent problem. The ones that stay broken are much eaiser to solve.

Hoping you are all good now.
 

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