# Furnace Won't Start



## Sandlapper (Apr 12, 2010)

This past weekend I needed my furnace but it would not work properly. I had 2 full bottles of propane, both of which were open and I made sure I had the thermostat set where it should most definitely come on. If I switched it to off, then back over to furnace, it would kick on for a few seconds then shut itself back off and not come back on. This is on a 2010 Outback Sydney Edition unit. Anyone have any ideas as to what it could be or how I could fix it. Are there any points i could clean to help it make better contact? Thanks in advance for any help.


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## CamperAndy (Aug 26, 2004)

A couple of basic questions first.

Were you on shore power or just on batteries?

Has it worked recently or in the past?

Can you do check on it now based on our recomendations?


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## Yukon Eric (Oct 14, 2010)

There are high temp cutouts in your furnace. Make sure you have all heat vents clear of mats etc. as well as your return air grill is not blocked. It needs full air flow to work properly. When you shut it off and try it again it may have cooled enough for the cutout to reset. They reset automatically.


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## Sandlapper (Apr 12, 2010)

I was on shore power this past weekend. I checked it again today and the same thing occurs, cuts on for a short bit, then cuts off and won't restart. I am plugged in to 30 amp service at home. And yes, it has worked in the past. I believe it was working Friday night, but started failing on me Saturday night. I checked all the vents and the return and they are all clear. What next? Thanks guys.


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## thefulminator (Aug 8, 2007)

Do you ever get any warm air out of it or just cold air? If it's cold air only you may never have ignition occurring.


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## CamperAndy (Aug 26, 2004)

Be outside and listen to the exhaust vent as you try to start it. Once the fan comes on you should hear the the ignitor come on, then the gas valve open, followed by the sound of combustion.Tell us what step it gets to as that will help tell where to go next.


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## egregg57 (Feb 13, 2006)

I think I have heard this story before!


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## Sandlapper (Apr 12, 2010)

The blower comes on just fine, but I have no ignition, no clicking, nothing whatsoever on the gas side of it. There is gas to the unit, but apparently its not entering into the burner assembly or whatever it is.


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## CamperAndy (Aug 26, 2004)

Then your fault is with the air flow sail switch. It detects combustion air flow and once met then it allows the unit to go to the next stage which is the igniters.

The flow switch could be stuck or failed but I will go with low voltage to the blower. The reason why I asked if you were on shore power was the fan speed is directly related to the DC voltage. Low voltage = low fan speed and this results in low air flow and the flow switch does not make. You need to get access to the fan and see what the voltage is at the furnace when you try to run it. It may just be a loose connection.


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## Sandlapper (Apr 12, 2010)

Well, you were exactly right CamperAndy. I didn't have a chance to check the forums yesterday, but I did manage to take the furnace out (which was in a very tight spot) and take it 1 hr. away to the dealer. They determined it was a bad connection on the sail switch, apparently a little loose or a bad connection, but anyway, its working fine now. Funny, i checked the forums this morning, and you were right on the money. Thanks for your help. Atleast now I know how this furnace works and how to get it out if I ever have to again (which i hope i don't).


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## CamperAndy (Aug 26, 2004)

Thanks for checking back in now that you got it fixed. Too often we never hear what the repair ended up being.


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## dwest369 (Feb 2, 2004)

Camperandy, great job diagnosing the problem. You are always there with a solution. Keep up the good work. I'm getting a great education just following your posts.


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## CamperAndy (Aug 26, 2004)

dwest369 said:


> Camperandy, great job diagnosing the problem. You are always there with a solution. Keep up the good work. I'm getting a great education just following your posts.


Thanks, I will submit your post to my boss when it comes time for my year end review.


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## dandee (Apr 22, 2010)

Having the same problem on my furnace is there a way that I can check the sail switch myself?


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## CamperAndy (Aug 26, 2004)

dandee said:


> Having the same problem on my furnace is there a way that I can check the sail switch myself?


Sure but on an older unit you really need to check all the connections. At least your furnace is easy to get to.

Access the furnace under the dinette and I believe you can get to the access panel for the wiring. Just make sure they are all tight and when you turn on the furnace you get 12 volts to the control wiring. It could be Black or Brown to the sail switch and red from the switch to the control board.

Also make sure there are no obstructions to the combustion air intake or exhaust on the outside, Shine a light in there and look for wasp nests.


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## ZHB (Mar 17, 2009)

Hey there Andy - I'm now having the same problem on my unit. Since you've been such a great help so far......

I have a 2009 300BH. I'm not sure HOW to get to the furnace - outside, there's just the 2 vent covers, and when I took the cover off inside, there are the 3 ducts leading away from it. It looks like the connections are down the side, but I'm very nervous to start tinkering around until I know what to look for.

Last weekend, our heat wouldn't stay on. It has worked before. I never got hot air coming out of the vents. I could reset the system and get the furnace to start blowing air, but no heat. Air flow was good in the top vent and out the bottom, although it smelled of propane to me. I would hear it clicking as if trying to light, but nothing.

I gather from above that the sail switch is key here. But do I need to pull the unit out of the cabinet into the RV to get to it?


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## CamperAndy (Aug 26, 2004)

If you heard the ignitor then your problem is not the sail switch or any of the other safety devices. After the ignitrer starts the gas valve should open. Go outside when you have your DW try to start the furnace, you listen for the gas valve to open. Let us know if you hear it or not. The ignitor will only run for 5 to 10 seconds then turn off, once you here it stop smell the furnace exhaust and see if you smell propane. Do not stick your face down there just wave your hand down there to move some of the exhaust so you can smell it for propane.


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## ZHB (Mar 17, 2009)

I'll give it a listen as soon as I have some help today. But what you said above (after I hear the ignitor stop, smelling propane in the exhaust) is what happened yesterday.


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## CamperAndy (Aug 26, 2004)

ZHB said:


> I'll give it a listen as soon as I have some help today. But what you said above (after I hear the ignitor stop, smelling propane in the exhaust) is what happened yesterday.


Then you may have a short in the ignitor that is allowing the spark to go to ground somewhere other then where the gas is. You will have to inspect the wiring and the installation of the ignitor to see where the issue is.


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## ZHB (Mar 17, 2009)

OK, guess what~ the problem "went away." Well sort of.

On Saturday, I distinctly heard the ignitor trying to go (twice) with no combustion, and then I smelled gas in the exhaust. Yesterday, I reset the system - including pulling the fuse - and then tried again. I also pulled the cover off, blew out the cabinet, and blew out the vents. When I turned it on again, the ignitor ran once, then on the second clicking, it caught. I tried it three more times, and it worked like a charm.

My only real concern now is that when I turn the furnace "off" the fan still runs a few minutes - is that normal?

And my other real concern is that since I'm not sure WHY it didn't light before, I don't know WHEN it will fail again. But it's in storage now until March.


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## CamperAndy (Aug 26, 2004)

ZHB said:


> My only real concern now is that when I turn the furnace "off" the fan still runs a few minutes - is that normal?
> 
> And my other real concern is that since I'm not sure WHY it didn't light before, I don't know WHEN it will fail again. But it's in storage now until March.


Normal cool down for a gas furnace to run the fan for short period after the burner turns off.

The issue could have been air in the gas pipe and it just needed to operate a few times to clear. There could be other issues but we can wait until next spring to look at them if it fails to start again.


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## ZHB (Mar 17, 2009)

BTW Andy - I meant to start my post above with "thank you for your help." Seriously. Your expertise has helped so much since I first got the OB.


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