Diagnosing new Atwood furnace

Jason977 · 01-13-2016, 04:39 AM

Instead of waiting on a service tech to get around to looking at my heater, I started looking at it myself.
This is on my new Vegas that I just picked up. The heater came on during the PDI, but then later when I actually tried to use it, it stopped working. I diagnosed the gas supply, checked continuity through the sail switch and limit switch, and verified power to the gas valve.

Currently, the furnace will light the first time I try, then won't re-light after it cycles off. I can reset the system (switch under the panel) and I can't hear it sparking when it's trying to light. Eventually I get the 2-flash error code.

Tonight I shut off the gas supply, removed the gas valve and burner assembly, capped the supply line, and turned on the system with the burner removed. When I turned the heater on, the ignitor sparked as expected, and the gas valve opened. When it failed to light (no gas connected), it paused for a bit, then the cycle restarted but this time the spark was weaker and some times it wouldn't spark. The third time, I only got a spark once or twice rather than the dozen or so that it did the first time.

My conclusion is that either the capacitor or the coil on the control board is bad. I looked for any problems with the ceramic insulator or wire, but didn't find any. Since I was working on this at night, I would think I would see any stray arcing.

Anybody have experience dealing with this sort of warranty issue? Right now my options are:
Deal with the hassle of working with my dealer (I haven't even discussed it with him yet)
Try to call Atwood directly and see if they'll help
Desolder the cap from the board and check/ replace, since that seems like the most likely culprit

**EA37TS** · 01-13-2016, 01:08 PM

Before talking to the dealer I would call Attwood themselves. They may send you the required parts and let you do the replacement yourself. They may also have another item or two that are known issues.

Then, when all else fails, contact the dealer.

Dwain65 · 01-14-2016, 03:35 AM

Quote:

Originally Posted by Jason977

Instead of waiting on a service tech to get around to looking at my heater, I started looking at it myself.
This is on my new Vegas that I just picked up. The heater came on during the PDI, but then later when I actually tried to use it, it stopped working. I diagnosed the gas supply, checked continuity through the sail switch and limit switch, and verified power to the gas valve.

Currently, the furnace will light the first time I try, then won't re-light after it cycles off. I can reset the system (switch under the panel) and I can't hear it sparking when it's trying to light. Eventually I get the 2-flash error code.

Tonight I shut off the gas supply, removed the gas valve and burner assembly, capped the supply line, and turned on the system with the burner removed. When I turned the heater on, the ignitor sparked as expected, and the gas valve opened. When it failed to light (no gas connected), it paused for a bit, then the cycle restarted but this time the spark was weaker and some times it wouldn't spark. The third time, I only got a spark once or twice rather than the dozen or so that it did the first time.

My conclusion is that either the capacitor or the coil on the control board is bad. I looked for any problems with the ceramic insulator or wire, but didn't find any. Since I was working on this at night, I would think I would see any stray arcing.

Anybody have experience dealing with this sort of warranty issue? Right now my options are:
Deal with the hassle of working with my dealer (I haven't even discussed it with him yet)
Try to call Atwood directly and see if they'll help
Desolder the cap from the board and check/ replace, since that seems like the most likely culprit

.

I would suggest getting an appointment with the dealer. Atwood has a policy about warranty repairs. They will NOT send warranty parts directly to the end user. They will send to the dealer and let them perform the work. I would not recommend performing repairs on on the pressurized system yourself unless you are a plumber and have the ability to test the system for leaks after reassembly.

Mr Sunshine · 01-15-2016, 12:56 AM

Call Atwood direct. My new Vegas had a problem with the furnace in the first week last summer. Without being turned on at the thermostat, it started to click repeatedly, like it was trying to start. The manual button on the furnace, accessed through the outside panel, stopped the noise. Atwood diagnosed a bad circuit board, and sent it to me at my next destination. Easy for me to install. Happy to continue our trip, and especially happy to avoid having to go to the dealer with that one!

Jason977 · 01-16-2016, 12:13 AM

Well, Mr Sunshine, you had a lot better experience than I did. The fellow at Atwood I spoke with agreed with my diagnosis, but wouldn't entertain the idea of sending parts to an individual.

Looks like I'm off to a dealer

Mr Sunshine · 01-16-2016, 07:48 PM

Sorry you are having to do battle with Atwood. Here are two forum posters who were told they won't send parts. And yet, I had zero resistance to having a replacement circuit board sent to me on the road.

So many questions: Was it that my problem was more obviously just a board? Could their policy have changed since June? Would you get a different answer if you called back and got a different Atwood person? Would a supervisor or manager authorize sending that part direct to you?

Anyway, good luck. Let us know how this is resolved.

Jason977 · 01-19-2016, 04:52 AM

I've been out of town, but I'm calling Atwood again tomorrow. If they don't send me a replacement board I'll let them know that I'm just going to order a Dinosaur board and report back here. No time to mess with a dealer when I can have the part installed in 30sec.

09 Challenger · 01-20-2016, 04:19 PM

Quote:

Originally Posted by Jason977

I've been out of town, but I'm calling Atwood again tomorrow. If they don't send me a replacement board I'll let them know that I'm just going to order a Dinosaur board and report back here. No time to mess with a dealer when I can have the part installed in 30sec.

Exactly what I would do at least you know its fixed

Jason977 · 02-24-2016, 04:27 PM

Well I'm going to have to eat crow on this one because I had it wrong... While I'm still annoyed at Atwood for not being more helpful and just telling me to take it to a dealer, I was wrong about it being the board at fault.

The diagnosis step that finally led me to this conclusion was turning on the furnace with the gas disconnected and the electrode removed but connected (I was holding the electrode and had a jumper to ground). As noted before, I would get a good spark across the electrodes at first, but the spark would get weaker and less frequent on subsequent attempts.

Next, I bypassed the electrodes all together, and just ran a jumper from the coil on the igniter board to (near) the ground. Doing this, I would always get a strong spark to ground, even across a very wide gap. My guess is there was a defect in the insulator that allowed the spark to short out. Note that I couldn't find anything visually wrong with it, and a multimeter showed no continuity between the electrode and ground.

In any case, I replaced the electrode and it's worked perfectly since. A dealer local to me said he couldn't look up the part because he (or his system) couldn't recognize the furnace model number. Regardless, I was able to identify the correct part he had on the rack. From my internet searches, it doesn't seem to be a very common style.
One of the few places I found it listed online here: Atwood 35100 Electrode Assembly for Small, Medium & Large Furnaces | American RV Company

I suspect a different style would also work in a pinch, but new mounting holes may have to be drilled, which would probably void your warranty.

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