atwood 8516-111 furnace died

[hpcbmw]

I've got an Atwood 8516 furnace in my 1997 FWC. Worked great with no problems last year. This year, I turned it on via the thermostat and nothing happened - no fan, no clicks, no nuthin. There is no electricity at the thermostat. There is electricity coming into the heater via the red wire on a 4 prong plug. That red wire connects to a 4 way block on the lower right side of the big round unit heater unit, which I assume is the fan motor (open the access door from outside, and the plastic protector flap and you see the round motor situated vertical, with the sticker saying "atwood mobile products" etc, a bunch of wires, mostly on the right, and down low on the right mounted with two screws to the motor is a 4 way block that is about 3/4" square). This has 4 prongs, the hot red wire coming in, plus a yellow, blue and another red. None of these wires have electricity, other then the hot red wire.

Could this 3/4" 4 way block be the culprit? If so, what's it called an how easy is it to get a replacement?

There is also a 1" x 1 1/2" box on the upper right with a reset button on top. That reset button is stuck in, and won't pop back out, but the wires all get electricity to them. I assume I should replace this as well. It says "w58-xb1a4a-5, amp 5, 250vac max, 50 vdc max mexico 96-10. Where would I find a replacement?
Thanks!

 

[Old Crow]

While you wait for a response from someone who has a clue (that ain't me!), take a look at this for component identifications, circuit diagrams, parts lists, troubleshooting checklists, etc.....

http://bryantrv.com/docs2/docs/hflamefurn04.pdf

I'm not sure I was reading it correctly but page 49 appears to say the circuit breaker for an 8516 III is part # 35791 and I see those on Amazon and Google Shopping

 

[Old Crow]

hpcbmw-

Uh-oh. I see the photos of the 35791 for sale online don't look like the one you describe.

Page 23 apparently explains that....

"On our 79 and 85 series furnaces we have two different types of breakers. The earlier 79 and 85 models and all 89 models used a rectangular slow blow breaker as pictured. Its sole purpose was to protect the motor. On late model 79 and 85 models we started using a finger-size combination breaker and on/off switch. Code required us to be able to shut the gas off at the appliance when servicing it. This switch accomplishes this by shutting off power to the blower motor, which in turn prevents the gas ignition system from coming on. Therefore, it is not only important to use the same amperage rated breaker, but also the same style of breaker."

The Parts Reference on page 49 lists the 35791 and another 5-amp-- the 37049.... but there's a problem...

35791 Breaker 5 AMP ✗✗ ✗ ✗ ✗
37049 Combination Breaker-ON/OFF Switch 5 AMP USE 35791

The Parts Reference contradicts the page 23 direction to use the same type breaker.

 

[hpcbmw]

Thanks Crow, I appreciate the help. I found the original owners manual for the heater, so have similar diagrams. The problem is that I can't tell from the diagrams what the breakers or solenoids or whatever look like - so I cant tell what I'm looking at!

I'll keep digging.

 

[Old Crow]

hpcbmw-

Yeah, I have the same problem when I look at exploded parts diagrams for my various vehicles. It's sometimes tough to match up what you see in the diagram with what you see on the vehicle.

But take a look at pages 23 and 24 of the service manual at the link I provided. I think you're describing your circuit breaker and relay in your original post.

Then go to the parts reference starting on page 49 for the part numbers and google for suppliers.

Perhaps another approach is to go to http://www.rvdealership.com/rvdstore/index.aspx?CustomerNumber=885555 and navigate down through furnaces to your specific model and look at the 'exploded view'. Those should be parts for your unit and many have photos. The only thing I don't like there is there aren't photos on all the parts and they don't show part numbers. But they do recommend you call if you have questions. (Come to think of it I don't know if that site is for end-users like us or for dealers. I got to it by clicking on the online parts catalog button at http://www.pplmotorhomes.com/parts/rv-furnaces/rv-furnace-repair-parts.htm. )

You still have the mystery of whether you need the old or new-style circuit breaker. Perhaps they could clear that up.

-OC

PS- The troubleshooting guide at the top of page 31 should be helpful. And of course you'll want to think about what changed since the furnace last worked... like possible wire damage by mice, corroded connectors, etc.

 

[hpcbmw]

After messing around with the furnace - blowing out dust, checking connections, etc,- I really found nothing wrong. I double checked the thermostat and found that hooking up a jumper wire, everything worked just fine. I can use the jumper for the time being, but a new thermostat will fix the problem. Here's a pic of the thermostat with jumper wire.

Thanks for the ideas.

 

[PaulT]

hpcbmw,

You might take a look at this thread on thermostats and the model that ski3pin found worked for him.

Paul

 

[Old Crow]

Thanks for posting the jumper pic, hpcbmw. Good to see you found the problem.

I hope nobody minds if I also use this thread to attach a few other links on the general subject of troubleshooting an Atwood furnace...

Here's a link to video which shows another way to bypass the thermostat, identifies the wire color scheme, and provides info on timing events by the circuit board.

And here's another on the 85xx-III series, changing the blower motor

Good familiarization and component identification info in those for all of us Atwood furnace owners.

Now I guess I need to put the service manual and troubleshooting info on my laptop so I'll have it with me when I need it while on the road. And maybe copy it to a thumbdrive to keep in the camper.

 

[ski3pin]

This has been added to the

Ultimate Furnace Thread

 

[hpcbmw]

Thanks Old Crow, great videos. If I'd had that info earlier it would have saved alot of messing around!

 

[Old Crow]

More to add to the thread for future reference (it's a rainy day here today)....

1. In post 1, hpcbmw noticed his circuit breaker reset button was stuck in and wouldn't pop out. Naturally, he wondered if this could be causing his problem. Later, he isolated his problem to the thermostat. So his problem wasn't a reset button that won't pop out. I wondered the same thing when I touched the reset button on my furnace. It was fully extended but went loose with my touch. I believe that's because its design is to pop out when it blows (interrupts the circuit) but in my case the outer shell of the button had been jounced out to the extended position. If the circuit breaker 'trips', the push button will be popped out but will offer some resistance to pushing it in to reset. An unpopped breaker is normal.

2. In the photo of the 8516-III in post 1, we see the time-delay relay (a/k/a the 'Klixon relay') at the lower right (beside the serial number label). I attempted to find that relay on my 8516-IV furnace but it's not there. Yet it's on the wiring diagram. I believe that's explained by a note on the diagram in the Sequence of Operation section (page 16): "Starting 7 / 2001 Relay and Circuit Board combined". Also, page 24 provides continuity and voltage test info for the relay. (But I've not even found mine yet).

3. In looking at the page 22 info on the Hydro-Flame mechanical thermostat, note the optional OFF switch. If that switch is off you can be fooled into thinking you have a bad thermostat. The temperature-setting slider will move but won't do anything. The next step will probably be to jumper the thermostat out of the circuit. And when that appears to resolve the problem you may conclude the thermostat is bad when all along it's the OFF swtich being an OFF switch.

4. The Hydro-flame mechanical thermostat has a 'heat anticipator' which controls how often the furnace cycles. It should cycle 5-6 times an hour. The anticipator is adjustable but you have to be careful not to adjust it down too low. Refer to page 22.

-OC

 

[hpcbmw]

Another member on this forum just sent me a White Rodgers 1E78c that he took out of his FWC. Thanks Dave!

I hope to install it in my camper next week and I should be good to go.