FURNACE WONT LIGHT 2000 ADVENTURER 37G

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muskoka guy

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I CANT LIGHT THE GAS FURNACE. IT LITE THE FIRST COUPLE OF TIMES . THE THERMOSTAT SWITCH WAS SO DIRTY FROM DUST THAT IT WOULD HARDLY MOVE. I THINK THE PREVIOUS OWNERS TOOK IT ON A LONG DIRT ROAD TRIP. IF I WIGGLE THE SWITCH I CAN GET THE ELECTRIC FURNACE TO START. IS IT POSSIBLE THAT THERE IS NOTHING WRONG WITH THE FURNACE I JUST NEED A NEW THERMOSTAT. THANKS IN ADVANCE


Edit by John:  changed message icon to Topic Solved
 

John Canfield

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First off, please don't use all CAPS - it make your post very difficult to read and it is considering shouting on forums.

Here's a troubleshooting manual.  Page 14 has a flow chart that should help you figure out what the problem is.
 

John Hilley

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I think it probably is the thermostat. You could try cleaning all the switch contacts in the thermostat. A new thermostat is probably a good idea nay way. I've replaced the thermostats in both of our motor homes.
 

Alfa38User

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There is no way to clean either the switches except externally or tiny relay contacts on the thermostat (Make and model might help here). Just pop the cover and clean what you can. Working the switches back and forth is about all you can do.

Report your results back here and we can perhaps give you some more tips as to prove that the thermostat needs replacing in respect to the furnace.
 

Garyk

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If you want to try to clean the thermostat, you can pick up some spray contact cleaner at a Radio Shack, it works pretty good and dries quickly.
 

Gary RV_Wizard

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Are we talking about a wall mounted thermostat or something internal to the heating unit?

Could you explain a bit more about what happens when it "doesn't light"?  Does the fan come on? Do you hear a clicking sound as the igniter sparks? If the problem is in the thermostat, none of these will occur.

 

muskoka guy

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thank you all for your replys. the manual say to turn off the gas supply at the tank. place the thermostat above room temp. says fan should engage which is does. says to wait five minutes and turn thermo below room temp. fan should shut off which is does. says wait two minutes then turn gas back on at tank and adjust thermo above room temp. furnace should light in approx 30 seconds which is does not . the fan just continues to run. as i stated the first couple of times i tryed to light it, it lit on the second try. i repeated this about 4 times now it is not lighting .the thermostat cover says rv confort.php coleman mack. i dont now if this tells you the model or not, i didnt see any other name or number. i can see by reading the trouble shooting section of the manual that john sent me (thanks again) where dirt built up in the furnace area could possibly cause trouble. i have not opened the furnace cover on the rear of the coach to look inside. as i stated before i think the previous owner travelled a long distance on dirt roads because all the air filters were very dirty. the inside of the coach was dusty, as well as most of the ductwork and return air passages.
 

Alfa38User

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A hint: Since you have turned off the propane at the source and tried to fire up the furnace in your testing, it would be a good idea to turn  on the propane then light the gas stove. Why? There is a very good chance that there is now air trapped in the propane system and lighting the gas stove for 5 minutes will purge most of it out. The furnace is very fussy about the propane/air mix whereas the stove is not.

After purging, when you try and light the furnace, do you hear a series (up to 3) clicks coming from the furnace?? (This is the igniter/flame detector trying to light the propane.) Do you smell propane around the exhaust port??

After 3 attempts to light (clicks) the furnace ignition circuit is locked out and the furnace has to be reset before another attempt is made. (Reset= turn the thermostat to a much lower temperature for a few minutes  before trying again.)

For the thermostat, Coleman Mack RVComfort is the brand but the model # is likely found under the cover which likely just pops off.  The manuals for the thermostat are available on line; Google RVComfort.
 

muskoka guy

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had the motorhome out on the weekend and discovered that the electric heat would work if i wiggled the thermostat switch . i was plugged into my friends house so i only had 120 volt 15 amp circuit. it tripped the breaker so i decided to shut of the furnace and  just put on a microfurnace heater. i shut off the furnace (so i thought) and was walking back to the house when i heard the furnace burner light . i went back to the mh and checked to see where the switch was on the thermostat. it was almost at the off position but just slightly toward the  gas setting. i guess this confirms that the thermostat in worn out and needs replaced. thanks for everyones suggestions
 

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