Furnace won’t ignite

gruehle · 03-16-2023, 10:29 AM

I have a 2014 Cougar 327RES model. My Atwood 8535-IV-DCLP furnace wont ignite. I’ve replaced the sail switch and that did not make a difference. It will turn on and I get just 1 or 2 clicks. Then, what sounds like a “puff” of air sound, like the igniter trying to light the burner but then it just blows cold air and turns off after about 1 minute. The diagnostic blinking light on the panel suggests and igniter problem.. I’ve bought a new igniter and burner BUT, the problem I’m having, is I cannot seem to figure out how to disconnect the gas line. EVERY Video on YouTube has this furnace mounted horizontally. The 327RES is a vertical mount. It looks like where the gas line runs, is behind a wall on the right side of the where the furnace is mounted. I have no idea how to get to it, in order to discconect and remove the burner assembly. Any advice would be greatly appreciated!

**chuckster57** · 03-16-2023, 10:59 AM

You’re going to have to access the gas line from inside the trailer. Depending on where your furnace is mounted you have to remove the return grill or a panel in front of the furnace. Make sure you use 2 wrenches when removing the gas line. There will also be 4 wires on the other side. Make sure you insulate ( cover) the 12V hot wire and label the 2 blue ones.

You may just have a bunch of mud dawber nest material on the burner.

FlyingAroundRV · 03-16-2023, 12:36 PM

Before you go to the trouble of disconnecting the gas, try cleaning the sail switch.
From your pictures, it looks like it would be easy to get to, it's mounted on the fan motor. They get filled with dust and lint and it stops the switch from activating. And when the sail switch doesn't activate, the heater behaves just as you describe.
Edit: the sail switch is on top of the fan case in the first pic. Be gentle cleaning the switch, it is quite delicate. Use a soft small paint brush or something similar.

**chuckster57** · 03-16-2023, 02:14 PM

Quote:

Originally Posted by FlyingAroundRV

Before you go to the trouble of disconnecting the gas, try cleaning the sail switch.
From your pictures, it looks like it would be easy to get to, it's mounted on the fan motor. They get filled with dust and lint and it stops the switch from activating. And when the sail switch doesn't activate, the heater behaves just as you describe.
Edit: the sail switch is on top of the fan case in the first pic. Be gentle cleaning the switch, it is quite delicate. Use a soft small paint brush or something similar.

If the igniter is clicking, the sail switch is operating as designed and can be ruled out. If the sail switch is faulty it won’t send 12V to the board and the gas valve won’t open and the igniter won’t try.

There is a “series” of steps the furnace takes to operate. Sail switch is the first, then the over limit switch. If conditions are met then the control board will open the gas valve and send voltage to the igniter. Once it does ignite the igniter becomes a flame sensor to keep it lit. The overlimit switch prevents the furnace from getting “over heated” and will cause the gas valve to close shutting off the flame.

Hope this all makes sense.. that’s the quick start guide.

dutchmensport · 03-17-2023, 07:30 AM

Before taking anything apart, take lots of photos of everything, so you will have a memory of how it all goes back together again. Once you disconnect wires, it's VERY easy to forget which one went where, even if there is only 2 wires!

Just my suggestion! Good luck!

martybmw · 03-24-2023, 09:37 PM

I had the same problem with my 21 3700 FL you could hear the igniter but it wouldn't fire and could smell the gas. Had to pull the furnace out from the inside cabinet (what a major ordeal) as they is no out side access. Then to make matters worse to get into it had to disconnect the gas lines which means no trouble shooting. Was able to see a spark coming from the wire going to the ignitor which turned out to be partially broke. Put a new connector on it and fired up. Of course only worked a couple time so again had to take the cabinet apart to get to the furnace. Replaced the ignitor ad all is well. The real annoyance was after my rig stayed at camping world for about 8 months after I purchased it waiting for parts and this exact problem they told me it was the gas regulator. Really like the unit and if anyone plans on getting warranty or any other service at Camping World well buyer be ware.

gruehle · 10-13-2023, 07:01 AM

Thanks. The sail switch was the first thing I replaced, even though the old one didn’t look bad, I figured it was a cheap option. It did not solve the issue. I bought a new burner and igniter but trying to get to the gas line has been the issue.

gruehle · 10-13-2023, 07:02 AM

Thank you! I agree on pics. I’m an avid picture taker when I’m working on something I’m not familiar with.

nuctrooper · 10-14-2023, 05:47 AM

What is your propane pressure? Get a propane pressure gage to determine the pressure downstream of the regulator. If you have a QD (for a BBQ), you can just get an adapter and plug it in there. If you don't, here's your opportunity to install a QD. It's actually pretty easy.
I ask because I had a similar problem with my furnace. It would sometimes light for a second or two, but would consistently blow out and not stay lit. My propane supply pressure was high in band (I forget the exact number right now - maybe 11"). Figured it needed more propane (crank it up must be better, right?) so i adjusted the regulator up about 2" - seemed worse! I then adjusted the pressure regulator lower in the band (9" I think) and tried just for fun, and the furnace started and ran the first time, and has run consistently ever since. Turns out there was too much propane pressure, even though it was in band. The adjustment is easy on the regulator - I just wouldn't do it without a gage or manometer. If you are out of other options, give this a try, and good luck!

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