Atwood Excalibur Furnace issue

BO

bootpacker

Member
Joined
Mar 21, 2015
Messages
12
Location
BC, Canada
Hi all, I am looking for advice about the broken furnace on my 2005 Eagle.

I was traveling in Colorado using the furnace regularly every night for over 4 weeks, until all of a sudden one night when I turned on the furnace it started making this really loud clunking sound that seemed to be coming from the fan. I attempted a couple more times and the same thing happened so I stopped. The next day I tried again, but this time nothing happened. The whole thing basically quit.

I brought the camper to a nearby 4WC dealer, and the guy in the shop was super nice and found time in his busy day to look at it. He thought that it could have been the thermostats and did some testing but could not figure out what was wrong. He called around, looking for ideas and possible solutions. In the end he suggested that it might be the motherboard but they did not have the equipment to test it. He believed that some RV places might be able to do that. He also suggested that I might be able to find a replacement but it would require some searching as they do not make the same furnace any more.

I also emailed a few more 4WD dealers close to home and basically told me that I probably need to take the camper back the the factory in California to put in a new furnace because it requires frame modification due to difference in size. Yeah, I love California but it is quite far away.

So, I am thinking that I should take my camper to a RV repair place to get it checked first but I really don't want to spend money just to find out that I need to replace the whole unit, plus the closest Atwood repair center is over three hours away.


Thank you for reading, and thank you in advance for any suggestion.
 
I took out the motherboard in my 1999 Eagle and took it down to the local RV repair place. They described my problem exactly ( not yours), tested the board, sold me a new one for a little over a hundred and I installed it. Problem solved. Testing was free.
 
Thanks for the reply. That's good to know that testing is free. I will start calling RV repair places to see who can do the testing.
Was the RV place you went to in Bellingham, WA?
 
If it has been running ok and a loud(ish) clunking sound associated with the fan started, I'd think the problem would be related to the motor and fans-- the turning portion of the furnace. I assume the sound seemed to be coming from something turning and perhaps had a tinny or perhaps a screechy character to it. (If not, please describe it)

There are fan blades on each end of the motor --- one called a 'combustion wheel' and the other the 'blower wheel'. Those assemblies are each mounted to the shaft with a set screw. It's possible one of the set screws became loose enough to allow its fan to slide down the shaft enough to contact the metal housing.

The motor assembly itself is clamped into place on the motor mount. It's possible that the fan assemblies are right where they should be and tight but the motor mount clamp has loosened enough to allow the motor (and it's attached fans) to move enough to cause contact.

That of course is pure speculation. I'm only making a guess based on your description of how the problem started.

But if that seems to be consistent with your experience, take a look at this video for details for access to the motor and fan wheels...


Arguing against that speculation is the fact that an FWC dealer looked at it and did some electrical testing and then said it might be the control board.

So at this point, I'm curious as to what happens when you first turn on the furnace. Once the thermostat calls for heat, the motor should run to clear out the combustion chamber before it opens the propane valve and makes its first ignition attempt. Does the blower run at all?

.
 
Thanks for the reply and video link.

No, right now the blower does not run at all when I turn on the furnace and turn up the thermostat

As to the clunking sound that it once made, It definitely had the "tinny" character.

It certainly did not seem like a motherboard issue to me but I think the shop guy suggested it because it was easy to do and worth finding out.

I think I should at least take a look at the motor
 
bootpacker said:
No, right now the blower does not run at all when I turn on the furnace and turn up the thermostat

As to the clunking sound that it once made, It definitely had the "tinny" character.

It certainly did not seem like a motherboard issue to me but I think the shop guy suggested it because it was easy to do and worth finding out.
Click to expand...
If you're interested in messing with it, I'd check that my furnace is similar to the one in the video (the 8516-IV in my 01 Hawk is--- it's just mounted vertically instead of horizontally), I'd follow that to pull the blower cover and check that the fans are clear and the motor turns easily (because of the noise). If you're lucky, the problem could be something simple. If not, it's relatively easy to get parts and replace them yourself.

A jammed-up motor may have tripped the circuit breaker so check it too. And be sure you have more than 11 volts to it.

If you have something going to get the board checked, all the better.

If you don't have the time or inclination to mess with it yourself, I think I'd try a mobile-RV guy or smaller RV mechanic who gives me some confidence he knows his way around my Atwood furnace model. These furnaces have been around forever and were used by many brands of RVs and trailers so there's no reason to take it only to an FWC dealer (unless you want to upgrade to a newer model).

Also- I find this service manual helpful. It's kinda hard to read as it's for multiple models and sort of pieced together. Yours is an electronic ignition or DSI (direct spark ignition) model (vice a pilot model).


.
 
I have about the same vintage furnace and have spent a LOT of time investigating issues with mine in the past. The symptom you describe does not sound like the motherboard, but rather something related to the fan. If the fan does not spin, there is a sail safety switch (which blows in the wind) that won't allow the furnace to light. It sounds to me like you need to do a "mechanical" inspection. Parts are available. I live north of Seattle. There is an RV company here that is an authorized Atwood service center: Here's their website: http://www.evergreenrvsupply.com/

Chris
 
Here's another video on an 85xx-series furnace having its motor replaced. I'm posting it because it shows the sail switch mentioned by Yukon (in post #9) and gives an interesting description of the sequence of operations. The whole video is worth watching for disassembly info but the sail-switch and sequence-of-operations info starts at the 4:40 mark.

 
Just wanted to update the result. I was visiting Portland and had time to visit the Rose City RV. It turned out the issue was caused by two broken connections and the guy got it fixed within an hour. Good shop by the way, fast friendly and reasonable price.

Thanks again to everyone that helped here on the forum.
 
You must log in or register to reply here.

Similar threads - WTW

ZO
2006 FWC Electrical Issue
Wandering Sagebrush
Wandering Sagebrush
PA
Truma furnace install.... Amazing!
2
BigRanchInSky
BigRanchInSky
WE
Q for this still running their old Atwood heaters
Saturn949
SA
RY
Furnace - What am I Missing?
ski3pin
ski3pin
Yama-Bro
Need help with fair value of 2015 Hawk
Yama-Bro
Yama-Bro

New posts - WTW

Back
Top Bottom