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Topic: Front furnace (Read 1094 times) previous topic - next topic

Front furnace

It got cold enough the other day that I thought I'd try the propane furnaces BEFORE I needed them. The back one worked just fine, but the front one just sits there, taking up space. I can get a click out of the thermostat, indicating that it is calling for heat, but that's it. No fan, nothing. First thing I did was check the fuse. It turns out that the front furnace and the fixed table light are on one circuit and the light was on, so that says the fuse is good. Just to be sure I pulled the fuse and Jo Ann started hollering that her light just went out.

Tomorrow is supposed to be a pretty nice day so I'll get out the meter and start checking things. Suggestions are welcome. I thought about checking to see of the fan actually turns, and then realized that if it didn't the fuse would blow. Fortunately the electric heat works just fine.

Re: Front furnace

Reply #1 –
Do you have a bay door that opens in front of the furnace exhaust?. If so, could be the switch that prevents it from running while the door is open.

Re: Front furnace

Reply #2 –
My previous rig (SOB) did the same thing after summer was over, turned out to be mud daubers all over the squirrel cage fan keeping it from spinning.
J.R.
99 U320 40' WTFE
Build # 5388

Re: Front furnace

Reply #3 –
David,

Link below to Atwood service manual - most likely covers the model in your coach.  Contains a trouble shooting section.

Also, you can Google "Atwood Hydro Flame trouble shooting" and find some helpful videos on YouTube.

http://bryantrv.com/docs2/docs/hflamefurn04.pdf
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Front furnace

Reply #4 –
David,

The prior responses contain good technical advice.
First, though, when these furnaces have been inactive for quite some time (a few weeks to months),  my experience has been that oxidation of wiring connections/switch contacts is a likely source of a "non-start" problem, i.e. - when you only get a thermostat "click".  A  bit of "wiggling" of contacts and preventive maintenance in the form of dielectric grease often helps:
See Randy's recent thread:

Furnace no go

HTH,
Neal

P.S. - If this turns out to be your solution, it may just start another "Bottle Rocket" thread.  😃
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Neal (& Brenda) Pillsbury
'02 U320 SPEC, 4200, DGFE, Build #5984
'04 Gold Wing
'07 Featherlite 24'
'14 Jeep Grand Cherokee Summit
MC #14494
Exeter, NH & LaBelle FL
Quality makes the Heart Soar long after Price is Forgotten

Re: Front furnace

Reply #5 –
My fairly new Atwood was doing that after we drove through a sandstorm and hurricane winds/rain coming down from the high country to Ajo. It had a fresh Dina board, so I was perplexed. I noticed a lot of dust in the compartment, so I got my compressor out and aired-out everything, including when it was running. Working fine now. (fingers crossed) .
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'

Re: Front furnace

Reply #6 –
Well, I've had a couple of nice days to poke around some. The manual referenced above is very helpful. At this point I'm thinking that either the thermostat is dead or the motor is dead. I'll keep poking. Worst case I'll add it to the list of things FOT will check next month.

Re: Front furnace

Reply #7 –
Make sure the On/Off switch on the furnace frame is switched to "On".
1997 U270 34FT Build 5140 Cummins 8.3 Allison 3060R
Solar 1920Watts, 14KWH lithium. Orion BMS.

Re: Front furnace

Reply #8 –
Tim, that's the part that I'm most concerned about. I suspect that it may not actually be turning on. Since there are only two wires I'm thinking that I may just try jumping across them and see what happens.

Re: Front furnace

Reply #9 –
Jumpers are quite valuable in diagnosis, start at the thermostat, voltmeter also quite valuable, eleminate one component at a time until it works, furnace has many safety switches.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Front furnace

Reply #10 –
Yes. If it's getting 12 volts, you can jumper the two blue thermostat wires and the furnace should start.
1997 U270 34FT Build 5140 Cummins 8.3 Allison 3060R
Solar 1920Watts, 14KWH lithium. Orion BMS.

Re: Front furnace

Reply #11 –
Was looking for a very short project to do this afternoon between other stuff, so jumped the two wires. Shortly thereafter the furnace came on. It seems that the on-off switch actually just lifts a small piece of springy metal (copper, maybe?) off of a contact point when the furnace is turned off and lets it snap back against the contact when turned on. Apparently the non-use for the past six months or more gave that springy metal a bit of a set so that it didn't make firm contact. It does now.

Temperatures are up around 70, so furnace not needed. Oh well, at least I now know what to poke at if the furnace doesn't behave when we get colder temperatures again.