Atwood Furnance problem

[jvowell1]

I have a 1996 Damon Intruder I got this past summer. It has an Atwood furnance model 8535. It would not light so I pulled the burner and there was a dirt dabbers nest on the orfice. I thoroughly cleaned . I set the gaps correct on the ignighter and made sure the clicking was sparking. Clicks but no light. I bought a new dinosaur board and installed. Still no light. Hooked up a mannometer and checked gas pressure and it was at 9 inches so I replaced the regulator. Now I have 11 inches pressure. Still no light. Looking at it in frustration trying to think what to do next, I covered the exaust port while it was clicking and it lit! I let it run for awhile, turned the thermostat down, and it shut off normally. Turned the thermostat back up. It clicks no lit. I covered the exaust again and it fired up, any thoughts what might be happening?

[Reddog1]

Moved to the Tech Issues forum.

Wayne
Moderator

[Jfet]

cruiseruser wrote:
A well known rv store wanted also $162.00 for the same switch.

The whole furnace doesn't cost much more than that!

[cruiseruser]

We had almost the exact same problem in a class C that my son owns. We did everything that you have completed, except for a new Dinosaur board. Check the sail switch. It has quite a lot to do with the air flow. After we changed his... we were golden.

By the way, check prices. You can get an aftermarket switch under $50.00 online. A well known rv store wanted also $162.00 for the same switch.

Good luck. Hope this helps.

[jvowell1]

Yes every thing else works great.

[enblethen]

Most LP gas valves have two coils. Test each of the coils for resistance, they should be nearly the same.
Does your other gas appliances work properly?

[jvowell1]

Yes the orfice is cleaned I have cheked and rechecked. The ignightor is a fixed position and I adjusted the gap to the correct setting. I thought about the wire sparking else where so I pulled it out and it was sparking across the igniter. Is it possible the gas valve are not opening enough?

[enblethen]

Did you clean the orifice?
Did you pull the burner out of the furnace and insure screen is clean?

[Gripnriprod]

Could be the spark is happening somewhere besides at the igniter tip as in jumping from the wire or elsewhere.

[kohldad]

Sounds like the igniter may not be in the correct location. By holding your hand over the exhaust, you are slowing the airflow down, letting the gas bubble build a little larger and reaching the igniter.