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Topic: Furnace not coming on. (Read 855 times) previous topic - next topic

Furnace not coming on.

Kind of bad timing considering we are looking at zero degree weather here in East Texas tonight.  :o

The furnace was working fin until this afternoon, then stopped coming on.  I just removed the cover and checked for loose wires, don't see anything loose.  Flipped the on-off switch on the unit.  Still a no go.  I don't see a problem at the thermostat, light and switched work and I can select the furnace mode.  Just nothing happens regardless of how high I set the temperature.

I checked the breaker and the fuse in the DC fuse box labeled furnace/hot water heater.  It looks intact.

The fan is not coming on at all, so its not getting to the point of igniting.  Any ideas on what else to check?

Fortunately we have the heat strip in one of the AC units, and I have a small heater in water bay and a light bulb in the pump bay that so far are doing the job. 


Joe Phebus and Jaime Trujillo
2002 U270 3410  Build: 5953 Motorcader # 18595
1200W Solar, 600AH Battleborn Batteries with Victron Components
1992 Geo Tracker

Re: Furnace not coming on.

Reply #1 –
Joe,

Try the trouble shooting document below to see if it gives you any ideas.  Good luck!


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
"It goes without saying..."

Re: Furnace not coming on.

Reply #2 –
Thank you, Chuck!

Joe Phebus and Jaime Trujillo
2002 U270 3410  Build: 5953 Motorcader # 18595
1200W Solar, 600AH Battleborn Batteries with Victron Components
1992 Geo Tracker

Re: Furnace not coming on.

Reply #3 –
Joe, If the furnace doesn't light at all, sounds like it could be the igniter.  It may just need to be cleaned.  You can give it a light sanding with some emory cloth just to clean off the carbon build up.  Sometimes this is all that is needed.
Mark & Bev
2001 U295 36'
Cummins ISC 8.3 350HP
Build #5802
Jeep Wrangler Toad

Re: Furnace not coming on.

Reply #4 –
Quote from: MarkC –
Joe, If the furnace doesn't light at all, sounds like it could be the igniter.  It may just need to be cleaned.  You can give it a light sanding with some emory cloth just to clean off the carbon build up.  Sometimes this is all that is needed.


Mark,  wouldn't I hear a click when it tries to ignite?  Or at least see the fan start first?  The Atwood unit it totally dead.  I only see  lights on the thermostat.  I'll have a look at that in the morning, as its certainly possible give it was working earlier today, though.  I'm going to pull all the fuses at the DC panel one-by one tonight see if maybe the panel has a mislabel.  The outside will have to wait 'til morning as its already bitter cold and too dark to see much.

Appreciate you help!

Joe   
Joe Phebus and Jaime Trujillo
2002 U270 3410  Build: 5953 Motorcader # 18595
1200W Solar, 600AH Battleborn Batteries with Victron Components
1992 Geo Tracker

Re: Furnace not coming on.

Reply #5 –
Our furnace(s) both acted dead. Granted we have "old" 1989 Atwoods. But they did come back on when I found and pushed the reset button accessible only from the outside.
Nitehawk,  Demolition Lady, & our NEW master, Zippy the speeding BB cat.
1989 Grand Villa 36' ORED
Oshkosh chassis, 8.2 DD V8
2006 Saturn Vue AWD

Re: Furnace not coming on.

Reply #6 –
Quote from: nitehawk –
Our furnace(s) both acted dead. Granted we have "old" 1989 Atwoods. But they did come back on when I found and pushed the reset button accessible only from the outside.


I see a button and pressed it, but didn't get a good result.  I'm suspicious that could be the culprit though.  It seemed "sticky", and not springing back when pressed as expected.  I just checked all the 12v dv fuses, they are good. 

I'm going to call a mobile repair service in the morning to troubleshoot.  If the weather was warmer, I might spend time trying to figure it out myself, but I'm new to the coach, not great on electrical so its worth a few bucks to get it done by a pro.

Its 5 degrees outside, and water bay and pump bays are keeping at about 34 degrees.  Just holding my breath that's enough to keep the water systems from freezing overnight.  We are warm enough in coach with the space heater and A/C heat strips.  I think if I keep the cabinet doors open and run a faucet every few hours, we'll be Ok.  ^.^d

Thanks!
Joe Phebus and Jaime Trujillo
2002 U270 3410  Build: 5953 Motorcader # 18595
1200W Solar, 600AH Battleborn Batteries with Victron Components
1992 Geo Tracker

Re: Furnace not coming on.

Reply #7 –
Try "snapping" the button several times. Or just keep moving the button back and forth. This might free it up.
I have even gone so far as to spray some electrical contacts cleaner into the button housing to loosen it up. Then blow the area dry before actuating the button.
Once you know it is dry and acting freely then you can go inside and try restarting the furnace.
Nitehawk,  Demolition Lady, & our NEW master, Zippy the speeding BB cat.
1989 Grand Villa 36' ORED
Oshkosh chassis, 8.2 DD V8
2006 Saturn Vue AWD

Re: Furnace not coming on.

Reply #8 –
Take a multimeter or a 12v test light and see if you have 12 volts after switch or reset breaker.  My furnace stopped working one night because the on/off switch went bad and wasn't letting 12v through.  If you have 12v after those then check to see if you are getting 12v to motor.  If you are then you have a bad fan motor.  If you don't get 12v then your control board may be bad.  The furnace will not ignite until it sees air movement from the fan via the sail switch which is next to the blower.
2002 36' U270 Foretravel

Re: Furnace not coming on.

Reply #9 –
The brushes in the blower motor could be stuck, give it a light tap or three with a small hammer. And yes .... checking for power at the fuse, switch and control relay is the best option to try first.
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Furnace not coming on.

Reply #10 –
Do you have a bay door that opens in front of the heater? If so there may be a micro switch that keeps the heater from coming on with the door open mine gets bent every now and then .
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Furnace not coming on.

Reply #11 –
Safety measure to prevent hot exhaust blowing on rear of bay door. Look for switch near the top corner of the bay door directly under the furnace. Push the corner of the door as if you were doing the Foretravel bump. First thing I would check.
Ed and Michele
2000 U295  36'  (Build #5600)
8.3 ISC 350HP.
2012 Jeep Grand Cherokee (Toad)
2001 Lance Truck Camper (Sold)
2001 Lazy Daze (Class C). RK Floor Plan (Sold)

Re: Furnace not coming on.

Reply #12 –
Sorry you are having a furnace startup problem. It is very important to clarify if furnace blower does not run, runs but burner does not get light (makes light roaring sound). Low house battery can prevent gas flame.

Using lightbulbs for heat - they are notorious for starting fires from anything touching the very hot bulb's glass. Years ago we used light bulbs in porcelain base with wire cage around the bulb and now do not recommend them. Much better to use several poplular Lasco 200 watt personal heaters, we use four of them.

For furnace, double check thermostat zones are correctly set. Try zone 1 to furnace & zone 2 to off. Furnace power source is likely behind white fiberglass bay wall cover. And that salesmen switch is ON.

Some coaches have furnace kill switches that are activated when bay door under furnace vent is opened. Just bypass switch by connecting both switch wires together.

Is propane level too low.

Re: Furnace not coming on.

Reply #13 –
You might check but with the comfort control you can not have a air conditioner and a furnace on,so by having one air conditioner on heat strip it will not let the furnace in the other zone come on.
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: Furnace not coming on.

Reply #14 –
Quote from: Lance Camper –
Safety measure to prevent hot exhaust blowing on rear of bay door. Look for switch near the top corner of the bay door directly under the furnace. Push the corner of the door as if you were doing the Foretravel bump. First thing I would check.

Woah.... might be it.  I have insulation in the bay and a bulb in there to warm it.  Maybe I tripped up something when I was weatherizing.  Thanks!
Joe Phebus and Jaime Trujillo
2002 U270 3410  Build: 5953 Motorcader # 18595
1200W Solar, 600AH Battleborn Batteries with Victron Components
1992 Geo Tracker

Re: Furnace not coming on.

Reply #15 –
Quote from: Barry & Cindy –
Sorry you are having a furnace startup problem. It is very important to clarify if furnace blower does not run, runs but burner does not get light (makes light roaring sound). Low house battery can prevent gas flame.

Using lightbulbs for heat - they are notorious for starting fires from anything touching the very hot bulb's glass. Years ago we used light bulbs in porcelain base with wire cage around the bulb and now do not recommend them. Much better to use several poplular Lasco 200 watt personal heaters, we use four of them.

For furnace, double check thermostat zones are correctly set. Try zone 1 to furnace & zone 2 to off. Furnace power source is likely behind white fiberglass bay wall cover. And that salesmen switch is ON.

Some coaches have furnace kill switches that are activated when bay door under furnace vent is opened. Just bypass switch by connecting both switch wires together.

Is propane level too low.


Thanks, Barry.    I wish there was a Lasco or any space heater within 200 miles of here.  Tried on Saturday and Sunday... nada.  I have one and am going to get 3 or 4 of them when this is over. 

Furnace blower is not coming on at all.  Checked the Thermostat.  Ours works as you state, furnace on zone with heat stips kill the furnace. Double checked that an zones.  Will get behind the bay wall cover tomorrow, weather permitting.

 
Joe Phebus and Jaime Trujillo
2002 U270 3410  Build: 5953 Motorcader # 18595
1200W Solar, 600AH Battleborn Batteries with Victron Components
1992 Geo Tracker

Re: Furnace not coming on.

Reply #16 –
Thanks everyone for the help with this.  Helped me to check in places I would never have though to look.

It ended up being something stupid.  A replacement Dinosaur board was installed, and when it was hooked up, one of the connectors was attached to the side of the board as opposed to directly to the pins where it should have been.  It was making minimal contact the wires, so I guess the installer tested and thought all was good.  Much have shook loose with the fan running to stop working.

Anyway as I was cleaning contact I did a double take... "that don't look right".  When I checked the Dinosaur website, sure enough, the plug was in the wrong place.  All is good now.

Good thing is we got through sub-zero temperatures on the heat strips, a space heater indoors, one in the wet bay and light bulbs in the pump bay.  I'm impressed as can be with how solid and airtight the coach is.  I daresay if we were still in the Sunseeker they would have carted us off in body bags.  ;)

Love this forum!  Thanks all! 
Joe Phebus and Jaime Trujillo
2002 U270 3410  Build: 5953 Motorcader # 18595
1200W Solar, 600AH Battleborn Batteries with Victron Components
1992 Geo Tracker

Re: Furnace not coming on.

Reply #17 –
Thanks Barry and Cindy for pointing me to the bay door kill switch! I had been checking everything else because of intermittent operation... I still don't have a wiring diagram/schematic that shows it or it would have been a lot easier!
A little contact cleaner and we are back in business!
Thanks again..
Tyson
Tyson
2004 295 3610 WTFS
2010 Honda CR-V
Motorcade #18344
AA1DS