Furnace won't light

FWIW: My furnace does this once in a while, but it only does this when the battery charge is relatively low...like there's not quite enough juice to do the sparking -- and yet there's enough to run the fan (but I can tell from the sound that the fan is running slower than normal).


I have a 05 Granby on a 99 F150 4x4 and have had the same problem on and off for the last 5 years-seems to be related to the battery. Out of habit, if I think I'll use the heater that night to warm up the camper (usually sleep cold-unless it's storming out) , I start the truck and turn on the heater before I call it a night-sort of warm it up. Have had the same problem in the morning-same procedure-turn on the heater and run out and start the truck. Also when I got the camper, I was told to turn off the power and turn it back on again if the heater doesn't work-doesn't work to often. If I leave the thermostat on all night and the battery is good-no problems.
 
Check the positive and negative fittings at either end to make sure they are clean and tight. I had bad crimp fittings that the wires fell out. (somebody had a bad day at the factory)
 
Mine did a similar thing and it was the sail switch or the high temp switch in the fan area in back.It shuts down if no air is moving or a high temp I can not remember which was bad. I jumped each one out(one at at a time) using a sharpened paper clip,(yes a paper clip) and stuck it into the wires to jump around the problem switch to locate the problem.mine had a schmatic drawing on the door to trace the wires. Good luck hope it helps.
 
After my 13-night trip with my camper last month, I need to update -- change -- my previous post on this topic.

A couple of times when I tried to start the furnace the fan came on but the sparker never clicked and then the fan shut off. Previously, when it did this mode of failure, it seemed like it only happened when the battery was low, but my battery was never low on this trip -- thanks to charging by my PV panel.
But -- and here's the weird thing -- the issue still seems to be power-related because I was able to get the furnace sparker to go by starting my truck, which feeds the camper battery.

And a new/different problem showed up: Very weak flame. I could look in the sight hole and see that one line of flame was wimpy and the other side was almost not running at all...so not much heat was coming out. When I noticed this the propane tank was pretty low, so I thought it had something to do with low fuel (even though the stove and propane refrigerator were working fine). And, indeed, when I got the propane tank refilled the furnace seemed to work as normal again...until it didn't again -- even with a mostly-full tank.
Does anyone know if the burner in the furnace can get fouled and require cleaning? I learned the hard way that that can happen to the burner in the 'frig, so maybe?
Has anyone seen the wimpy-flame problem in their furnace?
 
The burner can get clogged, dirty, rusty etc and not work correctly.

It is a pain in the butt to remove it and check it - but that is a sure way to see it's condition and clean it or replace it.
 
The burner can get clogged, dirty, rusty etc and not work correctly.

It is a pain in the butt to remove it and check it - but that is a sure way to see it's condition and clean it or replace it.


Yeah, that's what I figured...I'll check it out -- thanks. Have you (UglyScout or anyone else) removed/serviced the furnace/burner, and do you have any tips for steps that might be tricky?

I now also have a Wave heater, which I got because it doesn't use electricity to power a fan and all the heat it creates goes into the camper (since it has no flue), but even though the Wave will get my legs burning very quickly :p ...it doesn't heat up the whole camper as quickly as the built-in furnace. So that's why I need/want the furnace to be fully functional, too, especially since we're getting into winter camping season.
 
I now also have a Wave heater, which I got because it doesn't use electricity to power a fan and all the heat it creates goes into the camper (since it has no flue), but even though the Wave will get my legs burning very quickly :p ...it doesn't heat up the whole camper as quickly as the built-in furnace. So that's why I need/want the furnace to be fully functional, too, especially since we're getting into winter camping season.


New name should be two heater Mark! I took my built in out and have relied on just the wave 3. Does take a while for it too get fully warm but them I'm a tough guy :LOL:
 
New name should be two heater Mark! I took my built in out and have relied on just the wave 3. Does take a while for it too get fully warm but them I'm a tough guy :LOL:


Yeah, for a guy who's spent decades camping in a tent and/or out of the back of my truck in all seasons -- not to mention backcountry camping, even winter backcountry camping on skis in a snowcave -- I sure have become a wimp in just 5 years with an FWC camper! :p
But so be it -- I have no problem admitting the truth! :cool:
(now where's that generator?...I need to plug in my electric blanket.)
 
Does anyone know if the burner in the furnace can get fouled and require cleaning? I learned the hard way that that can happen to the burner in the 'frig, so maybe?
Has anyone seen the wimpy-flame problem in their furnace?


Hi Mark,

When you perform this nifty task....please photograph your work and share with us. I was wondering the same thing about cleaning the furnace burner....after all it saved the day with the refrigerator. My refrigerator burner seems to need cleaning annually (2008 Hawk).....however, my furnace has always worked flawlessly.
 
Hi Mark,

When you perform this nifty task....please photograph your work and share with us. I was wondering the same thing about cleaning the furnace burner....after all it saved the day with the refrigerator. My refrigerator burner seems to need cleaning annually (2008 Hawk).....however, my furnace has always worked flawlessly.


Will do.
My furnace burner has always worked fine, too, until now...but I said the same thing about the refrigerator until a couple of months ago. ;)
 
My furnace burner has always worked fine, too, until now...but I said the same thing about the refrigerator until a couple of months ago.
wink.gif



Same experience for me with the fridge.

The burner on the furnace has to be much larger. Maybe it just takes longer for the corrosion to build up on it to the point of causing problems.
 
Will do.
My furnace burner has always worked fine, too, until now...but I said the same thing about the refrigerator until a couple of months ago. ;)


Since you had two "failures" in a few months' time, could that be an indicator of some larger crud buildup? Does anyone know a way to flush the propane lines clean?

And to update everyone on the status of my original post in this thread, my furnace still won't light, but I've been busy doing other fall activities so haven't spent any time doing the suggestions in this thread.
 
I've had my entire furnace out twice... Don't ask.

I've got an older Atwood 8516-II so your experience may differ. All the work is done through the outside door. The hardest part in removing the burner is disconnnecting and reconnecting the gas lines. Once that is done you need a long 5/16" nutdriver or socket to get the sheet metal screws out and the whole thing slides out. Use a headlamp to see in the furance to find the screws.

I tried purging my propane lines with compressed air - I have no idea if it worked. But I was able to purge the valve/burner combo deal with air and I know that worked.
 
What model furnace does yours have?

I went a few rounds with my furnace and have now had the entire furnace out 2x and replaced way too many parts... But it works awesome now!!!


ARGGGHHHHHH!!! I spoke too soon.

I was all pumped up to hit an out of the way campsite that I have actually wanted to go to for years. This weekend was going to be one of the last days it would be open before it was closed by snow -- Anyway I get there, get the camper set up, turn on the furnace. Nothing, 3 cycles and it quits. Reset via pulling the fuse, 3 cycles, nothing.... Seeing as how it was going to be about 20 degrees or less over night, there is already snow on the ground and the wind is howling, and I have a 10 month old along, I cry uncle and head for home. Part way back we stop for dinner and I try the furnace again - it lights and works like a champ! ARGHHH!!

The only difference between the 2 locations, about 6000 feet in elevation. It works fine at my house at 200', a few weeks ago at the beach at 5', at our dinner spot at about 400' - but at 6000' I got nothing.

So is it the pressure regulator?
 
ARGGGHHHHHH!!! I spoke too soon.
Anyway I get there, get the camper set up, turn on the furnace. Nothing, 3 cycles and it quits. Reset via pulling the fuse, 3 cycles, nothing....
So is it the pressure regulator?


So, the sparker/igniter is clicking but the flame doesn't go -- is that the symptom? Or is the igniter not even clicking?
 
ARGGGHHHHHH!!! I spoke too soon.

I was all pumped up to hit an out of the way campsite that I have actually wanted to go to for years. This weekend was going to be one of the last days it would be open before it was closed by snow -- Anyway I get there, get the camper set up, turn on the furnace. Nothing, 3 cycles and it quits. Reset via pulling the fuse, 3 cycles, nothing.... Seeing as how it was going to be about 20 degrees or less over night, there is already snow on the ground and the wind is howling, and I have a 10 month old along, I cry uncle and head for home. Part way back we stop for dinner and I try the furnace again - it lights and works like a champ! ARGHHH!!

The only difference between the 2 locations, about 6000 feet in elevation. It works fine at my house at 200', a few weeks ago at the beach at 5', at our dinner spot at about 400' - but at 6000' I got nothing.

So is it the pressure regulator?


I too had this happen only a few times but it seemed to happen after not using the furnace for some time, What I assumed was maybe a "vapor lock" of sorts. What I did was leave the main valve on the tank in the on position and loosen the main fitting on the tank as if removing it. When I heard the pressure release I would tighten the fitting again. This solved the problem and I do this whenever it has been inactive and I don't have the problem anymore. Altitude should be a minimal issue. I live at 9,000' and it works 99.9% of the time. As I said it only happened a few times after it had been sitting too long.

I hope this may help.

Good camping! Paul
 
So, the sparker/igniter is clicking but the flame doesn't go -- is that the symptom? Or is the igniter not even clicking?


The fan comes on for its pre-fire 15 seconds or whatever, the ignitor fires, the gas valve opens, you can hear it burn for 2 seconds, then it goes out. It does this 3 times and quits.

I have a new Dinosaur board and it appears to be working fine the led comes on, a new ignitor which below 6000' feet seems to be working fine, plenty of gas as the stove works fine and the furnace works at home. Plenty of power as it did the same thing with or without the truck running....

It worked 3 weeks ago just fine and I haven't done anything to it since.

A google search points to checking the regulator - I'm sure it is the factory unit from 1993. If it doesn't allow enough pressure it may not operate at elevation.
 
The fan comes on for its pre-fire 15 seconds or whatever, the ignitor fires, the gas valve opens, you can hear it burn for 2 seconds, then it goes out. It does this 3 times and quits.

I have a new Dinosaur board and it appears to be working fine the led comes on, a new ignitor which below 6000' feet seems to be working fine, plenty of gas as the stove works fine and the furnace works at home. Plenty of power as it did the same thing with or without the truck running....

It worked 3 weeks ago just fine and I haven't done anything to it since.

A google search points to checking the regulator - I'm sure it is the factory unit from 1993. If it doesn't allow enough pressure it may not operate at elevation.


This is exactly the same problem I had. As I mentioned above just loosen the connection at the tank and let the pressure release. Then reconnect it.If you are having the same issue as I did it should fire for you.
 
This is exactly the same problem I had. As I mentioned above just loosen the connection at the tank and let the pressure release. Then reconnect it.If you are having the same issue as I did it should fire for you.


Thanks for the suggestion. :)
One question/clarification, though: When you've had this problem (fixable by loosening the connection) was it only the furnace that was affected? 'Cause when I've had the sparking-but-won't-light problem the stove and propane frig worked OK (as far as I could tell), it was only the furnace with the problem... :unsure:
 
Thanks for the suggestion. :)
One question/clarification, though: When you've had this problem (fixable by loosening the connection) was it only the furnace that was affected? 'Cause when I've had the sparking-but-won't-light problem the stove and propane frig worked OK (as far as I could tell), it was only the furnace with the problem... :unsure:


I believe so. The fridge was maintaining, but I never checked the stove, so I can't say whether it had the same problem. What you described though, with the furnace running for a few seconds and then shutting down sounded exactly like my problem. I don't even think about it anymore, as I just loosen the fitting, reattach it and leave for my trip. Once I do that it is never a problem on the road.

I hope this helps.
 
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