Furance lights then quits

[Becauseican]

Hello, I have a problem with my Atwood 15000 btu furnace in my Quantum 26rs. Fan comes on, after the 15 sec wait the gas lights off. It heats/burns for about 2 sec then stops burring (fan still running), after a few sec it tries to light off again. And the cycle continues. As it lights off I am assuming it is not the sail switch. Likewise, as it lights off I am assuming it’s not the HIGH temp switch. What might cause it to cycle on / off (gas, fan running), but only run about 2 to 3 sec. HELP PLEASE Thanks

[taylorbob1]

There have been many threads on this subject
Start by using the SEARCH function

I had a similar problem when I turned-on the furnace for the 1st time, 4 months after I purchased my rig.

Instead of dropping it off at the dealer, I did the following:
1) removed the external cover, then used compressed air throughout the inner workings
2) when that didn’t work, I removed the burner (just 3 screws after disconnecting the propane). I inspected and cleaned everything
3) finally, I adjusted the Spark assembly. Made sure the Spark was “long” enough (increased it to 3/4”). And that the Spark was close to the burner

Once I did all of these things, furnace has worked flawlessly for last 3yrs

[16ACE27]

Since it lights, but then quits you have one of two issues:

The Controller does not "see" the flame which is sensed by the ignitor - could be a bad ignitor even though it lights the gas.

The Controller is "bad". It may actually be a bad controller (common issue) or the board may be wet if you're in rainy weather, also a common problem.

If the Controller is actually bad i recommend you replace it with a Dinosaur board - better quality and longer warranty - probably cheaper as well.

[robmc5]

I am having the same issue, I actually posted about this also. I did have some water damage on the control board. I replaced it with a Dinosaur board and its doing the same thing, but it may solve your issue. I have an Atwood AFMD 30141. You need to look at the LED on the control board to see the error code. Mine would blink three times indicating an ignition lockout failure.

I would make sure there is no damage to the board, unplug and reseat all the connections. Also there is a switch on the side of the furnace and it called a "sail Switch", I would pull it out (do this slowly it will bend if you are not careful).Make sure the switch is clean and operates fully.

I went ahead and replaced the sail switch on mine, it was less that $20 on amazon.

I am still having the issue but these fixes may solve your problem. I personally like knowing how everything works. I am going to try Taylorbob1's suggestion about the spark adjustment next

Hope this helps!

[taylorbob1]

if your ignition is firing (click, click, click...and then a burst of flame for a moment or two), it may be that your ignitor isn't properly located next to the burner assembly
and/or, the ignitor does not have a large enough/long enough spark.

In another thread, it was stated that the spark tongs should not be any wider than 5/8".
However, I spread mine over 7/8" and also moved them closer to the burner

[lwmcguire]

Not familiar with Atwood heaters, but don't they have a flame sensor?

I have had flame sensors go bad on other furnaces over the years

[16ACE27]

Originally Posted by lwmcguire

Not familiar with Atwood heaters, but don't they have a flame sensor?

I have had flame sensors go bad on other furnaces over the years

The ignitor is also the flame sensor.

[lwmcguire]

Originally Posted by 16ACE27

The ignitor is also the flame sensor.

So very likely the issue

Thanks

[robmc5]

Mine will ignite, I could feel the heat but immediately shut off, like it did not sense the flame, I guess it the flame sensor could not work but the ignitor does?

[lwmcguire]

Originally Posted by robmc5

Mine will ignite, I could feel the heat but immediately shut off, like it did not sense the flame, I guess it the flame sensor could not work but the ignitor does?

that is sure where I would start, clean it first and if it goes out replace

[robmc5]

Just an update, I was able to get mine working. I replaced the control board and the sail switch and cleaned all the contacts. Just remember the vent extension has to be in place for the heater to work (I discovered that the hard way...lol!)

[Bob Denman]

Glad to see that you found and fixed the problem.

[OldWEB]

Originally Posted by Bob Denman

Glad to see that you found and fixed the problem.

The OP has not got back to this thread.... But robmc5 did some voodoo on their furnace and now enjoys the warmth.

[16ACE27]

Originally Posted by OldWEB

The OP has not got back to this thread.... But robmc5 did some voodoo on their furnace and now enjoys the warmth.

Chronic drive-by poster. Last drive-by thread was 6 months ago.

[Bob Denman]

Originally Posted by OldWEB

The OP has not got back to this thread.... But robmc5 did some voodoo on their furnace and now enjoys the warmth.

That's where my comment was aimed...

[GordSanClemente]

I had a similar issue.
It coincided with us getting attacked by moths.
Figured I would take the thing apart when I got home.
Get home, it fires right up.
Problem solved.

Next time I go camping, it doesn't work again.
hmmmm.

I email the manufacture and ask them what altitude the heater is rated up to.
I think they said 4,500 feet. Not to great here in California and other parts of the country.

My fix, I moved the igniter tips closer together, not further apart. (Set to the minimum spec)
Has worked above 7,000 feet now.

[OldWEB]

Originally Posted by Bob Denman

That's where my comment was aimed...

Oh I got that! I was just making comment that the OP left a legacy that robmc5 acted on and won.

[Down South]

The OP must have got it fixed. He never came back to respond nor has he even logged in since the 11th.

[vkb]

Originally Posted by Becauseican

Hello, I have a problem with my Atwood 15000 btu furnace in my Quantum 26rs. Fan comes on, after the 15 sec wait the gas lights off. It heats/burns for about 2 sec then stops burring (fan still running), after a few sec it tries to light off again. And the cycle continues. As it lights off I am assuming it is not the sail switch. Likewise, as it lights off I am assuming it’s not the HIGH temp switch. What might cause it to cycle on / off (gas, fan running), but only run about 2 to 3 sec. HELP PLEASE Thanks

YOU MIGHT TRY THIS....we learned from an old camper...when the gas on our refrigerator would not come on..
LIGHT A BURNER ON YOUR GAS STOVE ... it seems to clear the line of any air for some reason...it has worked for us a couple times...IT MAY OR MAY NOT WORK ON YOUR FURNACE...but does not require a lot of effort to try it..
good luck !

[MJC62]

OP be like Elvis he left the building!