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Atwood 8500 IV Won't Light Ron Maskell 9-2-08  
I have an Atwood Hydro flame 8525 IV Furnace installed in my RV. The Furnace goes thru the correct sequence of operation until it get to the lighting of the flame. I hear the gas valve open and the igniter sparking. It doesn't seem to start. The furnace does this three times and then shuts down and blinks a led three times ( for three times ). I can smell propane at the exhaust port. The other gas appliances seem to work fine. Any idea what is causing the problem. The furnace is a very closed in area with very little access. Do I have to take it out to fix it? The discharge seems to go below the floor.
Re: Atwood 8500 IV Won't Light roger 12-31-17  
Have a atwood 8500IV and a duo therm comfort control thermostat. Start the furnace and fan starts blows air but never lites. Fan never shuts down until I go to inspection cover and use the switch and shut it off even when I shut off the power the the thermastat. Has propane to the reg valve never here it open or any code indication at the red lite tried it several times with no luck.The A/C's work fine using thermostat.
Re: Atwood 8500 IV Won't Light Keith 9-2-08  
Hi Ron, Seldom do you have to remove an Atwwod furnace to fix anything. If you're getting spark and a propane smell, I'd look for mud dauber/wasp/bug nests in the exhaust tube or on/in the burner area. After you pull the exhaust tube, Turn off propane, disconnect the propane line at the burner, remove the screw on the front round edge and 3 - 4 screws in the back around where the exhaust tube goes, disconnect the igniter (red) wire and black wire. Pull out the burner. Hope this helps. Good luck!
Re: Atwood 8500 IV Won't Light Roger zzz 5-1-11  
There's never (or rarely) any answers to questions on these forums. Just more people piling on with their problems. What a waste of space and time.
Re: Atwood 8500 IV Won't Light Erik 11-6-08  
I have an atwood 8500-iv series furnace in my 5th wheel. The blower comes on and it tries to light but won't. If I crank up the temp., it will fire up and run. What would cause this?
Re: Atwood 8500 IV Won't Light Steve 4-23-14  
Thanks for the great advise. I pulled my burner out as you suggested and found a paper wasp nest and two golf ball size mud dauber nests. The burner hood was also chock full of mud and the orifice was blocked with mud. I cleaned it all out and it works perfectly now.
Happy Camper
Re: Atwood 8500 IV Won't Light brian 6-6-14  
I have an 8525 III. And followed the directions and pulled the burner and found a large spiders web in the grid inside once cleared the burner light and works thanks for the info...took about 1-2 he's not really difficult.
Re: Atwood 8500 IV Won't Light Fredette 10-27-14  
Our furnace won't blow warm air and it goes on and off.
It was working last night, we started it up without opening the slide out which comes very close to the vents. We are getting ready to hit the road but now have no heat!
Re: Atwood 8500 IV Won't Light Jim Hickling 11-9-10  
You were spot on about the mud daubers. I pulled the three screws, pulled out the burner unit and found a nest the size of a golf ball right around the burner unit. cleaned up the inside ansd reassembled and the unit fired up perfectly. I had exactly the same symptoms as the original complaint. fires up shuts down blows for awhile and the three blinks of the diode. thanks!!!
Re: Atwood 8500 IV Won't Light Mike 9-21-08  
I have an atwood 8500-iv series furnace in my terry camper. The blower comes on and then you can hear it ignite, but it wont stay lit. It keeps doing this. What should i do?
Re: Atwood 8500 IV Won't Light George 12-15-09  
Replaced bad computer board but it still dosen't lite. It's a new dinasour board. The valve indicator led light does not show red (valve is open) and of course does not show green furnace has ignited. It's as if the sail switch or the fan & limit switch is not letting the circuit complete to the board. ???
Thanks for any help.
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