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furnace blows but doesn't heat
Yahoo Message Number: 49059
Hello, We have an '84 22' RL LD named Lucy!  We Love Lucy! The problem is: the furnace blows, but no heat comes out.  The propane is turned on and there's plenty of propane in the tank.  Is there a pilot light in the furnace that could've gone out?  My husband and I just took over the restaurant he's been managing for the last 1 1/2 years and he's very busy, so I'm trying to find out what the problem might be.  Has anyone out there ever had a similar problem?  Thanks for any advice you can give me.  I'm planning on taking her into the RV place later this week, but it's quite a ways from here, and if this is something we can fix I'd rather do that.
Kathy from Oregon
Re: [Life With A Lazy Daze RV] furnace blows but doesn't heat
Reply #1 –
Yahoo Message Number: 49066
Hi Kathy If you haven't done this before and are not familiar with RV furnaces leave it to the experts. The older Durotherms killed a lot of people and they sold this part of the operation to Suburban (sp)if yours has a pilot lite the thermocuple could be bad . Whatever it is, it is not fireing up and some safety is not letting it lite. If you haven't done anything to it for a long time it really needs cleaning and inspected to be sure the carbonmonoxide is venting outside. It's not worth it so take it to an RV tech that know all there is to know about RV furnaces. We want to see you down the road.
Sincerely Robert & Roberta SKP#702 01 Red RK
Re: furnace blows but doesn't heat
Reply #2 –
Yahoo Message Number: 49067
I had a similar problem in our old 22' 91 model - I don't know if it was the same furnace as you have.  In this case we had to replace the controller board in the furnace.  There was no pilot light, just an igniter.  There was no test for it - they just replaced the board.

Steve Holmstrom "Bob" 1998 30ft IB

Quote
Message: 6 Date: Mon, 10 Jan 2005 22:18:50 -0000
 From: "Kathy" binghams@...>
 Subject: furnace blows but doesn't heat

Hello, We have an '84 22' RL LD named Lucy!  We Love Lucy! The problem is: the furnace blows, but no heat comes out.  The propane is turned on and there's plenty of propane in the tank.  Is there a pilot light in the furnace that could've gone out?  My husband and I just took over the restaurant he's been managing for the last 1 1/2 years and he's very busy, so I'm trying to find out what the problem might be.  Has anyone out there ever had a similar problem?  Thanks for any advice you can give me.  I'm planning on taking her into the RV place later this week, but it's quite a ways from here, and if this is something we can fix I'd rather do that.
Kathy from Oregon
[Non-text portions of this message have been removed]
Re: [Life With A Lazy Daze RV] furnace blows but doesn't heat
Reply #3 –
Yahoo Message Number: 49071
At 10:18 PM 1/10/2005 +0000, you wrote:

Quote
We have an '84 22' RL LD named Lucy!  We Love Lucy! The problem is: the furnace blows, but no heat comes out.  The propane is turned on and there's plenty of propane in the tank.  Is there a pilot light in the furnace that could've gone out?
Pur 22' is a 1980, so the model year is fairly close. The heater we have does have a pilot, and you have to light it each time you start it up from having the gas turned off. The procedure is fairly straightforward...pop off the front cover and the instructions should be printed on a paper on the inside of the cover.
 Be sure you have the propane tank itself turned "on" so gas will flow, and then you'll have to do the pilot lighting thing. Once you have it lit, the heater is operated by the thermostat and will continue to work until you shut down the propane gas again.

Good luck, and let us know if this doesn't work.

Sonsie
Re: [Life With A Lazy Daze RV] furnace blows but doesn't heat
Reply #4 –
Yahoo Message Number: 49074
Thanks for the help!  I'm on my way to work, but I'll try it tomorrow and let you know.... :-)

Kathy
Re: furnace blows but doesn't heat
Reply #5 –
Yahoo Message Number: 49084
Hi Kathy,
 First let me say that I know NOTHING about these things, but I did a quick search on the www.rv.net forum (tech issues section) and found these links for troubleshooting an RV furnace. Hope it helps!
 http://www.marksrv.com/furnace_trouble_shooting.htm http://www.atwoodmobile.com/Service/Trouble/dsi.cfm

Everything I've read indicates that you should have a professional look at it and not try to fix it yourself, but maybe you'll get more expert advice from the LD mavens here. Good luck.

Livia
Re: furnace blows but doesn't heat
Reply #6 –
Yahoo Message Number: 49144
"the furnace blows, but no heat comes out."
 We had the same problem with Ladybug when we bought her. The circuit board had to be replaced. The previous owner had a blowout on the passenger side rear outside tire. The force dented the metal and broke the wooden wall in front of the tire. The circuit board was behind the wall. The previous owner told us about the blowout, which was why he replaced all 7 tires before he sold it.

Karen
Re: furnace blows but doesn't heat
Reply #7 –
Yahoo Message Number: 49147
Quote
the furnace blows, but no heat comes out.  The propane is turned on and there's plenty of propane in the tank.  Is there a pilot light in the furnace that could've gone out?  My husband and I just took
Ours is an '83, so the furnace is probably a similar vintage to yours.
There are several possibilities:

- Insufficient propane was available at the valve at the time you tried it, and the furnace cycled into a failsafe mode after trying one failed ignition cycle. When this happens, turn the thermostat off, and after the fan has stopped, turn it back on. Shortly after the fan comes back on, you should briefly here a 'sparking' as it tries to ignite (auto ignition, no pilot). If successful, you will see the flame thru the small inspection window.
 This behavior is normal if the propane has been turned off for awhile at the tank, then back on.
 - A problem could occur with the fan motor at this vintage, where it does not spin fast enough due to varnish in the bearings or windings shorting. In this case, the 'sail switch' will not activate from the low airflow. Replacing or overhauling the fanmotor is the cure.
 - The first problem we had with our 10-yr old unit on purchase was an inoperative heater due to a bad relay on the control board. This is repairable.
 In sum, I had to both refurbish the fan motor and replace the relay in ours within the first year of ownership - no problems in the many years since.

Steve
2004 FL
2013 Honda Fit
Re: [Life With A Lazy Daze RV] furnace blows but doesn't heat
Reply #8 –
Yahoo Message Number: 49155
Hello, Thanks for the advice.  I think I'll take Lucy
Re: furnace blows but doesn't heat
Reply #9 –
Yahoo Message Number: 49190
"In this case, the 'sail switch' will not activate from the low airflow."
 Just to expand on that a little...the sail switch is a paddle inside the furnace that is pushed aside, closing a switch, when the blower is running full blast. It's a safety feature: if the sail switch isn't activated, the burner CANNOT light. This prevents a situation where the burner is flaming but no air is being moved, which could lead to overheating and fire, carbon monoxide leakage or other undesirable things.
 The key is that if the blower isn't working--or working well enough, as Steve suggested-- the burner will be prevented from lighting, and all you'll get is cold air. This can result from an old fan motor that doesn't move air fast enough to displace the sail switch paddle...OR from partially drained house batteries. (Or from a wasp or mouse building a nest against the sail switch! ;-)
 You should check the batteries first, and if they are fully charged, then suspect the motor.

Andy Baird
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: furnace blows but doesn't heat
Reply #10 –
Hello,

I am reading old forum posts trying to figure out why my furnace does not fire up. I have only had my 1986 22' for a short time. The hot water heater fired right up, but the furnace only blows cold air. There are some pages missing from my owner's manual, unfortunately I am pretty sure they are the pages regarding furnace operation. I can wait until I have the mobile rv service guy comes to do an inspection, but just curious as to whether the original poster on this got the situation resolved.

Cynthia on the Central Coast
1986 22' Multi-Plan
Re: furnace blows but doesn't heat
Reply #11 –
Quote from: '86LazyDazeBlaze  - 
Hello,

I am reading old forum posts trying to figure out why my furnace does not fire up. I have only had my 1986 22' for a short time. The hot water heater fired right up, but the furnace only blows cold air. There are some pages missing from my owner's manual, unfortunately I am pretty sure they are the pages regarding furnace operation. I can wait until I have the mobile rv service guy comes to do an inspection, but just curious as to whether the original poster on this got the situation resolved.

Cynthia on the Central Coast

 The furnace requires more gas pressure than the water heater. Make sure your propane tanks have plenty of gas.

2002 30' IB
Re: furnace blows but doesn't heat
Reply #12 –
   Hi Cynthia. Since you have owned your Lazy Daze, has the heater ever worked? The heater won't turn on flame until it verifies that there is air moving. The aptly named 'Sail' switch verifies this. You'll notice there is no air filter to clean or replace, so dust can build up on the 'sail' making it heavy enough that the fans air velocity won't be able to activate this switch. This switch won't allow the pilot to light. After the pilot light is on there is a few seconds delay before the main burner comes on. Also the voltage at the control board needs to be at least 10.5 volts at the heater before it will allow the heat to come on. If you are plugged in does the fan run faster?
   In a motorhome of this early vintage, you may need to manually light the pilot first, before the heater burner will come on. Someone else may be able to answer this question. My 1980 (SOB) with a Duotherm, needed the pilot lit before you could run the heater. Hope this Helps... RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
 
Re: furnace blows but doesn't heat
Reply #13 –
I have only had the LD since late October and have not successfully operated the furnace. I do not have a manual for the Suburban furnace and cannot tell where the pilot light would be lit or where the sail switch is. From all I am reading on this forum, it sounds as though I should get a quick release propane line installed into the cabin and use a catalytic heater instead of the furnace. The furnace fan makes an incredible racket. I am taking her to the shop later this week for a look over. I have a feeling that a number of the systems have been overlooked for quite some time. The good news is that she ran like a top all the way from San Dimas to San Luis Obispo on the day of purchase. I have not taken any other trips other than short jaunts since then.

Thanks for all the input, I am a complete RV Newbie, Cynthia
1986 22' Multi-Plan
Re: furnace blows but doesn't heat
Reply #14 –
Quote from: '86LazyDazeBlaze  - 
I do not have a manual for the Suburban furnace and cannot tell where the pilot light would be lit or where the sail switch is.

From all I am reading on this forum, it sounds as though I should get a quick release propane line installed into the cabin and use a catalytic heater instead of the furnace.
The furnace fan makes an incredible racket. I am taking her to the shop later this week for a look over.
The furnace has its own solid state ignitor, no pilot light.
The sail switch can make a bunch of noise, even when running. Our 1983's heater sounded terrible.
A catalytic heater is a good addition for supplemental heat but falls shorts shorts as primary heater, you will want it fixed, if possible.
Do have an experience tech work on the furnace, it needs to be reassembled in an air-tight manner, to prevent harmful gases from entering the coach.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: furnace blows but doesn't heat
Reply #15 –
Quote from: NADAZE!  - 
The furnace requires more gas pressure than the water heater. Make sure your propane tanks have plenty of gas.

Quote from: '86LazyDazeBlaze  - 
I have only had the LD since late October and have not successfully operated the furnace. I do not have a manual for the Suburban furnace and cannot tell where the pilot light would be lit or where the sail switch is. From all I am reading on this forum, it sounds as though I should get a quick release propane line installed into the cabin and use a catalytic heater instead of the furnace. The furnace fan makes an incredible racket. I am taking her to the shop later this week for a look over. I have a feeling that a number of the systems have been overlooked for quite some time. The good news is that she ran like a top all the way from San Dimas to San Luis Obispo on the day of purchase. I have not taken any other trips other than short jaunts since then.

Thanks for all the input, I am a complete RV Newbie, Cynthia

Were you able to get this repaired?

An old propane regulator could also be the problem. Try having it replaced.


Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264