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nukid68 · 12-19-2019, 12:52 PM

JUst when I thought all was good, I realize the bedroom is colder than front. And, today, water is frozen. Then discover the rear furnace has not been coming on. I checked the fuse in the thermostat, the 15amp fuse in the fuse panel. Not sure why it doesn't even start the fan. Of course I would be broke so have to DIY. any ideas where to look?

nukid68 · 12-19-2019, 02:58 PM

I am heading outside to check power at furnace, but 6" of snow is keeping me going slow. I have 12 volts at thermostat, but fan never comes on. So I hope it is not thermostat, cost $80 at local rv shop. there goes next months pay. lol. Will get back on if I find issue or not.

nukid68 · 12-20-2019, 10:40 AM

Well, I don't know what wires are what at the furnace, nothing marked. But...at one wire I did have 12 volts. So I guess that is positive, maybe?

exrench · 12-21-2019, 07:13 AM

If you can find two connectors on the circuit board marked"thermostat",you could bridge them with a screwdriver(or a coin). If the fan comes on, you can conclude the thermostat or it's wiring is at fault. Otherwise it is the furnace that needs attention.

oldnavycdr · 12-22-2019, 08:26 AM

Make sure the switch at the furnace is on. Mine is located on the blower housing.

mchero · 12-22-2019, 10:19 AM

PLEASE post the make/model of your furnace.

6" of snow is nothing!

Here's my adventure a couple nights ago:

9:00pm 4" of snow 10 degrees out.
DW informes me that rear bedroom cold. Cycle the thermostat, rear furnace dead.
Atwood 8520-IV, I had previously installed a dinosaur fan 50 plus a couple years ago.
When I removed the cover i saw a green led on the board. This told me that I was getting power to the furnace and the thermostat was calling for heat but no blower motor.
Breaker on fan housing verified functional with my volt meter. Sometimes a hung sail switch could cause this condition so I turned off thermostat to the rear and pulled the control board, clipped a couple wire ties and removed all connections out of the way so i could pull the fan cover. After i removed the cover i found the sail switch clean and functional using my V.O.M. I cleaned the connections on the sail switch and wiped down the housing.
It is possible to service these furnaces installed, you have to strip out the board and some cables. Also, having the proper tools is a must.
As i was installing the board and wires i spotted the culprit, the blue wire (power) line that connects to the fan power lug on the control board has a tap splice for the blue wire feeding the control board. This tap/splice is not weatherproof and after some time they will corrode and not get a good connection. I ended up cutting and splicing the three wires.
This was all happening at 10 degrees. Didn't get back inside till 11:00. Proper clothes and tools needed.

nukid68 · 12-22-2019, 09:21 PM

OK, maybe at 69 I am complaining too much. clothing is not right either. My hat's off to you for that repair work at 10 degrees and dark too. but thanks for the info, it is possible I may have sane issue. will pull the board out and check what I can. So far the main furnace is keeping us ok, specially under covers. thanks all so far for the comments, they are appreciated.

nukid68 · 12-22-2019, 09:22 PM

Quote:

Originally Posted by oldnavycdr

Make sure the switch at the furnace is on. Mine is located on the blower housing.

mine is on. thanks

nukid68 · 12-22-2019, 09:23 PM

Quote:

Originally Posted by exrench

If you can find two connectors on the circuit board marked"thermostat",you could bridge them with a screwdriver(or a coin). If the fan comes on, you can conclude the thermostat or it's wiring is at fault. Otherwise it is the furnace that needs attention.

will check that tomorrow, hope it is that easy. thanks

nukid68 · 12-23-2019, 09:45 AM

well, I don't know what happened but last night seems it started working. Wife said she thought it felt warmer than usual. I mean the temps have gone up but.

this morning however, I walked past a vent and felt air. Bent down and lo and behold, it was blowing hot air. And it has come on regularly today. I am not complaining just really thankful. As the saying goes, "thank you Jesus"! And thanks to all who advised of fixes. Much appreciated.

Solo_RV_Guy · 12-23-2019, 09:55 AM

Quote:

Originally Posted by nukid68

well, I don't know what happened but last night seems it started working. Wife said she thought it felt warmer than usual. I mean the temps have gone up but.

this morning however, I walked past a vent and felt air. Bent down and lo and behold, it was blowing hot air. And it has come on regularly today. I am not complaining just really thankful. As the saying goes, "thank you Jesus"! And thanks to all who advised of fixes. Much appreciated.

Hi Jim-

I'd encourage you to track down the actual problem because the next time this fails you might not be in such a warm location

.

Intermittent problems are a royal pain because they never seem to fail when you've got all your tools, the time, and decent weather - and especially if you have a repair technician's clock running... but they'll fail again the minute it's cold, you don't have tools, or the repair tech just pulled away.

That you've jostled some wires and circuit boards around makes me think of a poor (likely corroded) wire connection or 2. The tap splices are notorious (use one that's a size to small - it will work until the primary wire flexes enough and the wire breaks... but you cant see it under the plastic; I found one of these failures on a police radio in a squad car) for creating connections that will fail in a few years. You might go back and tug, twist, and otherwise man-handle the wires and see if stuff stops for good so you can do a real repair.

Good luck and safe travels to you and Nichole.

mchero · 12-23-2019, 03:54 PM

Jim.....

What is the make/model of the furnace??????

Solo_RV_Guy has an EXCELLENT point...reliability! You need to correct the issue, especially, like myself, living in below freezing weather.

When your water lines start freezing you can risk cracking valves/connectors and such. Not a repair project you want to start in the middle of winter.

timjet · 12-29-2019, 06:57 AM

Yup, you have not fixed this, it will reoccur.

I've had 2 issues with our furnaces. One I had to replace the upper computer board. You can test this by replacing that board from the front furnace that works.

The other issue is the switch on the blower motor was off. I think this acts as a circuit breaker and switched off by itself. A simple reset and all was well.

mchero · 12-29-2019, 09:48 AM

The Atwood 8500 series furnaces have two crappy wire taps. Over time these wire taps fail to keep a good connection. While the furnace is running if you move some of the wires the fan will quit.
I replaced these taps.
I have a burner, two sail switches and two igniter/probes on order. When they arrive i'm pulling the blower out of the front furnace and giving it a good cleaning. I'll inspect the burner and replace if needed. I'll replace the sail switch.
At least every season these furnaces need a good PM. If they sit for too long they get dirty, connections on the board need to be cleaned and such.