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Atwood 8535 III furnace problem?

Bubba_Bill
Explorer
Explorer
'95 Damon Intruder. Furnace just quit working, blower ran, no ignition. Motor replaced last year, worked 2 months through Winter O.K. Tested O.K October. Replaced sail switch with 'replacement no.' switch, but paddle slightly smaller. Replaced board with Dinosaur board (figured it was due!), still: blower runs, no ignition, tries to ignite, shuts off, repeats. Open outside door: starts right up! I can close outside door(s) and runs happily. I checked just about everything for mud daubers, nests...you name it. Blew out chamber with compressed air. I'm about to try adding a piece of alum tape to increase size of sail switch paddle. Any ideas Guys? Bill
16 REPLIES 16

enblethen
Nomad
Nomad
Clarification:
With the access door closed, do you hear the ignitor clicking?
If no inspect the silicone ignitor wire and it's routing.

Bud
USAF Retired
Pace Arrow


2003 Chev Ice Road Tracker

donfrump
Explorer
Explorer
Bubba Bill wrote:
Sail switch I bought lists as replacement for dozens of models, including mine. As I mentioned though, the paddle has less surface size than the old one. And it could be defective! It's a pretty cheap item. The regulator on mine looks pretty old and I have no way of measuring the output, so I'll try the new one. Stove burners all burn blue, so unlikely it's the regulator.


seeing as u ur self says the furnace runs perfectly once front removed to me that eliminates a ton of things including regulater

Bubba_Bill
Explorer
Explorer
Sail switch I bought lists as replacement for dozens of models, including mine. As I mentioned though, the paddle has less surface size than the old one. And it could be defective! It's a pretty cheap item. The regulator on mine looks pretty old and I have no way of measuring the output, so I'll try the new one. Stove burners all burn blue, so unlikely it's the regulator.

donfrump
Explorer
Explorer
Bubba Bill wrote:
I am referring to the furnace access 'door', or panel. Should have made that clear. My dealer friend here suggested moving the combustion wheel a bit to see if that helped. He and his mechanic had no idea. The Atwood 'troubleshooting' info listed regulator as no.1, though it seems o.k. In any case, I bought new regulator and when I replace , will report back.



thanks as I thought that's what you meant That's why I suggested restricted air flow Really if the furnace starts and runs fine just by removing this door maybe its a defective /wrong sails switch?

Bubba_Bill
Explorer
Explorer
I am referring to the furnace access 'door', or panel. Should have made that clear. My dealer friend here suggested moving the combustion wheel a bit to see if that helped. He and his mechanic had no idea. The Atwood 'troubleshooting' info listed regulator as no.1, though it seems o.k. In any case, I bought new regulator and when I replace , will report back.

donfrump
Explorer
Explorer
The deal is the furnace will start and does work, the main flame does work its not like it does not work that's the strange part

Quote: Open outside door: starts right up! I can close outside door(s) and runs happily.

OP are you talking about when you leave the Motorhome door open is when the furnace runs properly?

Old-Biscuit
Explorer III
Explorer III
donfrump wrote:
enblethen wrote:
The only "air flow sensor" is the sail switch.
Opening outside access door should have no effect on air flow through air chamber.
No ignition could be a grounded electrode conductor pinched in the door or damaged in such a way that it grounds to the door.


boy surely if it was that simple the OP would see that right away?
no? yes? beats me.In my view removing outside cover could improve the air flow


It is improving the air flow........but it's the combustion air flow that is being improved NOT the room air flow

OP stated:
blower runs, no ignition, tries to ignite, shuts off, repeats
Tries to ignite........it is sparking but main flame doesn't light (no ignition)

Intake air restricted OR the spark electrode is not positioned correctly and the improved air flow moves the 'spark'
Is it time for your medication or mine?


2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31

donfrump
Explorer
Explorer
enblethen wrote:
The only "air flow sensor" is the sail switch.
Opening outside access door should have no effect on air flow through air chamber.
No ignition could be a grounded electrode conductor pinched in the door or damaged in such a way that it grounds to the door.


boy surely if it was that simple the OP would see that right away?
no? yes? beats me.In my view removing outside cover could improve the air flow

enblethen
Nomad
Nomad
The only "air flow sensor" is the sail switch.
Opening outside access door should have no effect on air flow through air chamber.
No ignition could be a grounded electrode conductor pinched in the door or damaged in such a way that it grounds to the door.

Bud
USAF Retired
Pace Arrow


2003 Chev Ice Road Tracker

donfrump
Explorer
Explorer
Bubba Bill wrote:
'95 Damon Intruder. Furnace just quit working, blower ran, no ignition. Motor replaced last year, worked 2 months through Winter O.K. Tested O.K October. Replaced sail switch with 'replacement no.' switch, but paddle slightly smaller. Replaced board with Dinosaur board (figured it was due!), still: blower runs, no ignition, tries to ignite, shuts off, repeats. Open outside door: starts right up! I can close outside door(s) and runs happily. I checked just about everything for mud daubers, nests...you name it. Blew out chamber with compressed air. I'm about to try adding a piece of alum tape to increase size of sail switch paddle. Any ideas Guys? Bill



People??? posters here need to READ the op message before posting!!!
the furnace works 100% fine its not like its not working all he said was he had to remove front cover for it to start and runOpen outside door: starts right up! I can close outside door(s) and runs happily.
sounds like air flow sensor problem to me

Old-Biscuit
Explorer III
Explorer III
That sounds like air intake is blocked/obstructed/restricted.

And/Or

Spark electrode out of position.....incorrect gap
Is it time for your medication or mine?


2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31

enblethen
Nomad
Nomad
Could there be a wire pinched in the frame of the door? It could be the ignitor wire that goes across the face.

Bud
USAF Retired
Pace Arrow


2003 Chev Ice Road Tracker

Bubba_Bill
Explorer
Explorer
MH is in the storage building right now, it's 24 degrees here today! Went down there a while ago and tried something I hadn't before. I loosened the main door screws just enough to allow a crack between the outside main door which apparently left just a tad more air and it started right up....Hhhhm. Got it warm enough to cycle the furnace down to the lowest 50 degree thermostat set ing and left my little electric heater for now 'til it warms up a bit.

enblethen
Nomad
Nomad
Have you checked the ECO for continuity?

Bud
USAF Retired
Pace Arrow


2003 Chev Ice Road Tracker