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Atwood furnace problem

Our stern small guy was re-built in 2001. It's getting cooler here at 5k, so I fired the rear yesterday morn. Fan came on, heard the "click" (sail switch?) but no heat!  Shut it down, pulled all the wire connections to check for tightness, etc. Yes!, it fired heat, I was so proud. Proud until this morn, when it did the same thing. I've got a spare card on board, looks to be easy to replace, or do I have "deeper" problems? Thanks, M
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: Atwood furnace problem

Reply #1 –
Mike,

When it fails to heat is the igniter clicking?  Is the gas valve opening (12 VDC to it? propane smell in exhaust?)?
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Atwood furnace problem

Reply #2 –
I hear the "click", will check for power at the gas valve, no smell. Not too sure why it worked after dinking with the wires, though. If we still lived up north in the "green & grey" where the furnaces get heavy use, I'd prolly pull it, but this is a "Southwest" coach.
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: Atwood furnace problem

Reply #3 –
What I have found many times is that there small bugs that crawl in through the orfice and then this creates a blockage not allowing gas to flow through. You would have to remove the burner and solenoid assembly and clean out the orfice, I think that it screws in to the pipe from the solenoid.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Atwood furnace problem

Reply #4 –
Quote from: red tractor –
What I have found many times is that there small bugs that crawl in through the orfice and then this creates a blockage not allowing gas to flow through. You would have to remove the burner and solenoid assembly and clean out the orfice, I think that it screws in to the pipe from the solenoid.

We've had "mud daubbers" get into previous furnaces, and the after-market screens worked fine. (even though Suburban voids warranty if used) This problem is different.  ???
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: Atwood furnace problem

Reply #5 –
Not mud daubers, tiny nats that get into the orfice and plug it.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Atwood furnace problem

Reply #6 –
I found spiders in the tube and orifice in our furnace.
The selected media item is not currently available.Bill&Doris 97 U270 36'
University of Parris Island Class of 66
Semper Fi  Build# 5174 MC#17094

Re: Atwood furnace problem

Reply #7 –
Quote from: red tractor –
Not mud daubers, tiny nats that get into the orfice and plug it
Still doth not explain why it did not work, then worked, then did not work, all in a 24-hour period.
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: Atwood furnace problem

Reply #8 –
Manual with some trouble shooting tips:

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


Old thread from when I rebuilt our furnace.  Has some tips from other members on what can go wrong:

Need Hydro Flame Furnace Burner
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: Atwood furnace problem

Reply #9 –
I recall the connections to the circuit board causing issues.  The circuit board location is such that they do see some weather.  One "unplug" and "plug" might work for a day but cleaning the connections should last longer.  I use dielectric grease to keep corrosion at bay.  If you decide to replace the circuit board (and I'm not saying you need to) the aftermarket Dinosaur Electronics brand is good.  I have one in one of the two furnaces in our coach.  The other OEM board is still working fine.
John Fitzgerald
1991 U300 (SAI) Side Aisle Island Bed 40'
Detroit 6V92 with Allison Retarder
Meridian (Boise), Idaho

Re: Atwood furnace problem

Reply #10 –
I have replaced the burner assemblies on both front and back furnaces of our 1995 U280.  They rust thru and the propane/air mixture fails to burn correctly.  I used the newer part numbers that are available.
Tom and Linda
1995 U280SE #4636

Re: Atwood furnace problem

Reply #11 –
You might try tightening the plug that plugs into the board by using a small screw driver to press on the connectors in the plug. use dielectric grease after tightening. this solved my problem when my furnace was intermittent.
Bill
Wild Bill Colston
1997 Class A Towing 2016 ford F150 XLT extended cab with Golf cart in 8 ft bed or a 2004 Jeep Grand Cherokee
Retired Aircraft Maint Tech A&P Line Crew Chief
Pilots lisc--------Commercial and Multi Eng

Re: Atwood furnace problem

Reply #12 –
Quote
Still doth not explain why it did not work, then worked, then did not work, all in a 24-hour period.
More...Like Quote
That's pretty common, Mike. I've had two furnaces that did the same. I recommend you clean all the connections and replace the board. It will likely fix the problem and if it doesn't you'll have a nice shiny board to admire every time you open the furnce compartment.
jor
93 225
95 300
97 270
99 320

Re: Atwood furnace problem

Reply #13 –
Do you have two heaters?
If you do swap the control boards to see if the problem moves to the other heater.
John Duld
1995 U320C SE 40'

Re: Atwood furnace problem

Reply #14 –
Ditto on reply #12. Get some good contact cleaner and plan on checking at least annually.

CAIG Laboratories: DeoxIT & More at DX Engineering
These guys make good stuff.
Every day is a gift
Bob and Pat
2000 36 U295 cummins 350hp
Coach has been sold thanks to MOT 11/2016

Re: Atwood furnace problem

Reply #15 –
When the propane has been shut off from mine for a long period of time I have to recycle the on/off switch of the thermostat a bunch of times but it always does light. Sometimes 20-30 times. I listen for the second click which is the igniter. If I don't hear a second click I turn it off and back on again.
1994 U280, Build 4490
Deming, NM.