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 2/21/2011 8:49 AM
 

Just an update on the furnace situation (Yes, it's still broken. Didn't have a need for it over the summer but now I'm wanting to take off somewhere). After doing some research online I discovered that if I partially cover the exhaust vent on the outside of the trailer when the furnace is activated it will light. The theory is the end of the igniter has gotten moved so it doesn't spark in the proper spot and therefore won't light the gas. When the exhaust is restricted it holds enough gas in the furnace that it saturates a larger area which includes the area that the igniter is making it's spark. Anyway, it worked so it looks like I'll be pulling it out and checking the igniter position and giving the furnace a good cleaning.

Thanks all for the help!

Ron

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 2/24/2011 5:58 PM
 
If the sail switch is defective, the furnace shouldn't try to ignite. Most of these furnaces have an electrode that sits above a screen on the burner. If that screen has rusted out, no circuit will exist and the ignition electrode can fire all day with no results. I just replaced the burner screen on one of my furnaces because of this very issue.
Also, lots of bugs like to get in those furnaces. Be sure to blow the furnace area out with air periodically.
If its the circuit issue I describe above, your furnace should try to light three times and then shut down. At least that is the way mine works.

The part I replaced was about $30. This is the section that Gismo addressed in his post. In our furnaces, the sensor actually looks for a flame, not heat. I'm not sure how it does that but according to a furnace class I attended, thats the way it works.

Libby and John and RV the CAT www.TheRollingHome.com 1999 Fleetwood Discovery 37V Unit 38 Fort Clark Springs Brackettville, TX towing a 2005 Chevy Colorado Z71 4x4 Click here to see our current location
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 2/25/2011 2:06 PM
 

Thanks John!

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 2/26/2011 7:29 AM
 
it is the carbon molecules in the flame that completes the electrical circuit to let the control board know there is a flame present and keep the gas valve open. it is a very small curent flow. again even if it looks clean take some very fine sandpaper and clean it up. you have the same type of flame sensor in your frig. because of the very small curent flow that is why it is important to clean the contacts on your circuit boards and keep the flame sensor clean. if it lights when when covering up the exhaust from building up gas in the furnace seems like you would hear a pop or small explosion or something from the gas building up. let us know how you make out.

mike
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 3/14/2011 11:53 AM
 

Got it fixed. The orifice and tube had some garbage in it. Additionally I moved the end of the igniter a little closer to where it is supossed to arc and a little farther away from the case and gave the unit a good cleaning. It really wasn't nearly as bad of a job as I thought it would be. The worst was getting it out of the coach and putting it back in. If I have any more trouble I'm going to put quick connects on the electical connections.

Thanks so much for the help. It's greatly appreciated!

Ron

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