# Furnace Problems



## rddog8691 (Mar 11, 2007)

I purcheased a 1990 coachmen and had the unit checked by a dealer due to some problems, one being that the furnace would not turn on,they checked it and said there was a wire off. Long story short after usung the MH on a trip i ran the furnace all day then sometime overnight it stopped blowing warm air although the blower continued to work. 
any ideas


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## wickedmouse383 (Mar 11, 2007)

RE: Furnace Problems

Does your furnace run off of propane? If so is the propane tank empty?
I have an older model and it solely runs off of propane.
Just a thought.


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## rddog8691 (Mar 11, 2007)

Re: Furnace Problems

not out of propane i actually just had it topped off prior to the trip


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## hertig (Mar 12, 2007)

Re: Furnace Problems

Is there a guage which shows it to be still full?  It is not out of the realm of possibility that there is a leak in the system.  

Next, some RVs have a shutoff valve in the gas system to shut off the propane if the propane detector goes off.  Check to ensure that gas is actually getting to the burner.  

Then you need to start looking at the burner and the control board, which I don't know anything about.


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## utmtman (Mar 12, 2007)

Re: Furnace Problems

Funny but I had that same problem with my tent trailer and they found three different problem that caused our problem, one was a fuse, another was the igniter, and third we actually had propane line freeze on us twice and would not allow enough gas to ignite.


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## rddog8691 (Mar 14, 2007)

Re: Furnace Problems

I had someone else tell me that the lp regulator or line could have froze what would the fix be for that


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## Kirk (Mar 17, 2007)

Re: Furnace Problems

First of all, what make is your furnace? They all work pretty much the same but there are significant differences. The most common cause of a furnace blowing but not lighting the flame is what is called the "sail switch" not closing. The sail switch is a switch that is closed by a movable vane in the air path from the blower that moves the air through the furnace. That blower is actually two blowers on opposite ends of one motor shaft, one providing combustion air from the outside and the other moving the air from the inside of the RV through the heat exchanger to heat the interior of the RV.

The sail switch is a safety device to prevent the opening of the propane valve if there is not enough air movement. There are many different things that can cause it not to close. Were you plugged into shore power when the furnace failed? If not, try it when you are plugged to shore power to see if it works. Low battery voltage will cause the blower to turn more slowly and that can cause the sail switch not to close, thus you get blower, but no heat.


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## ARCHER (Mar 17, 2007)

Re: Furnace Problems

Had a similar issue, it was the electronic board for the furnace.


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## rddog8691 (Mar 20, 2007)

Re: Furnace Problems

The furnace is a Suburban and when the problem occurred i was not plugged into shore power (boondocking). I furnace ran fine for the first two days but on the third day it would stop blowing hot air. Prior to the trip when the problem occurred i did install brand new batteries in the coach. What happened was when i woke up in the morning it was freezing inside the coach and when i checked the air vent it was blowing cold air. I then turned on my oven and the furnace began to blow warm. Is it possible to test the sail switch


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