Furness Help in a 2005 3500RL - Montana Owners Club

BigSkys · 02-13-2010, 02:07 AM

Hello, I have a 2005 3500RL Montana, Do I need to be on AC power in order for the Furness to ignite and work, I could not get it going on just the 12 volt supply, the bower worked but that was all. Thank you for any help.

cman · 02-13-2010, 02:17 AM

Your need to check your 12V suppley does your 12v light work. your converter might be out. you can hook up a batty charge up to the batty

steves · 02-13-2010, 02:57 AM

If the blower is coming on you have a 12 volt feed. Are you sure you have propane?

BigSkys · 02-13-2010, 03:22 AM

Yes the 12 volt light works, and I did have a charger on it also, battery is full charge. I talked to Keystone tect yester day, she told me it had to be hooked up to AC power to ignite the burner. I am not sure if there is a converter in this 5er, at least I can not see one, where would it be located? I was thinking it should run on 12 volts, I have no way to hook it up to AC where it is sitting, later to day I am pulling it to a CG for a three nite stay, it is only 45 de right now, would hate to get up there and find that I can not get heat into it, wife would not be happy with me. I have never run the heat in this 5er yet.

BigSkys · 02-13-2010, 03:25 AM

Oh and yes both tanks LPG are full, I just hat the port side turned on.

steves · 02-13-2010, 03:33 AM

Make sure your selector is pointing to the correct tank. Suggest you turn on both tanks just to make sure. Your problem is very much like running out of propane...I know....it happened to me when I left NJ in December.

jimcol · 02-13-2010, 04:16 AM

As Steves stated if you the blower is working you have 12volt power to the furnace. I'm sure all the furnaces in the Montana's are 12 volt systems so one can boondock in cooler climates. Try a burner on the stove to make sure propane is getting into the 5'er gas distribution system. If gas is in the system then you might check at the furnace to make sure you did'nt get a blockage like a spider web in the orfice. Outside of this you are going to have to listen at the furnace to see if it is trying to light. You will hear the igniter clicking. These are just some simple steps to check. If you can provide more info on your findings to these questions perhaps we can be more help. Jim

BigSkys · 02-13-2010, 06:50 AM

I had all the burner on the stove going, and the water heater would ignite and burn. now to find a way to get at the furness to check it out, I can see where the LP gas line goes in the bottom, there is a vented oak board in front of the first step that goes up to the bedroom, I think the ferness is under there. I can not say for sure if I heard it tring to ignite. I will try to check it more when I get to the CG, hope I am not going to be up all night tring to get it going. thank you all for your help.

Art-n-Marge · 02-13-2010, 07:47 AM

I have a 2006 3500RL. The furnace/heater is next to the entry door side of the rig behind the basement doors. If you swing your entry door completely open, the furnace vent is just to the right of the door. The furnace will be behind that.

To get to it there are a couple of clips to rotate in the basement, then you can remove the panel. The furnace assembly will be to the very left. You should also see the converter to the right of it screwed down to the floor. You MUST have a converter, too!

I do not believe you must have 110v for the furnace to work.

All that said, it seems like the problem may be not getting propane to the unit or the igniter isn't firing for a number of reasons. Unfortunately, there are so many possible causes I wouldn't be able to debug and check anything unless I was there. There are some MOCers who are experts at heating/cooling and hopefully they'll post soon.

If the blower starts up, you should be able to hear the burner kick on soon afterwards. It does not take a whole lot of power to kick in the igniter. While a real low battery is a possibility, the blower would not run for very long on a low battery.

Good luck on this one. Not having heat this time of year is NO FUN.

ON Edit: Jimcol has excellent advice that when you take the panel off to check the furnace be prepared with a vacuum hose or brush of some kind to clean out what might be in there - spider webs, dust, wood shavings, etc. I looked back there for another reason some time back and found that area really needed to be cleaned up pretty good. During manufacturing they don't clean back there to save time and stuff can also collect over time. You might check for loose wires or "burnt" components, too.

HamRad · 02-13-2010, 08:08 AM

Bigskys,
The person you talked with at Keystone does not know what she is talking about. As others have indicated the furnace works on a 12 volt system. If you have everything working as described it sounds like you may have a system control board failure. Ask me how I know!

When I would attempt to start the furnace I could hear the click of the igniter trying to light the propane. It would try for 3 times and then stop completely. We traced it down to a bad control board. Specifically the igniter would not work.

We took the part down to one of our local RV parts places and they just happened to have a replacement. Took it home and installed it and the furnace started right up!

Good luck and please let us know what you did to get it working.

HamRad

ols1932 · 02-13-2010, 12:35 PM

The furnace works on +12 volts DC. The only reason you might have to be connected to 110 volts AC is if your batteries are discharged. Then the furnace will work off the +12 volts DC coming from the converter. Yes, your rig has a converter unless the previous owner has disconnected it and you have solar panels with an inverter. There is a difference between a converter and an inverter. A converter "converts" ac voltage to dc voltage. An inverter "inverts" dc voltage to ac voltage. That's all you have to remember.

For those who say you have to have 110 volts in order to operate the furnace, what do you do when you want to dry camp? These things are made to operate completely apart from shore power, water, and sewer.

If the blower worked, then you have +12 volts to the furnace. It could be the circuit card is bad. The circuit card determines when to open the valve for the propane to come into the furnace igniting circuits.

Orv

Ozz · 02-16-2010, 01:01 AM

Yep, it operates on 12 volts. These circuit boards are programmed to operate safely, if anything is marginal, it will not allow the gas valve to open. First there is a purge, the blower runs for a short time, then the ignition system sparks, in a home unit there is a 120 volt glow igniter, we all them a HSI, hot surface igniter, commercial rooftop units may have a spark, or a glow coil. But, the RV's have a 12 volt spark system. This spark ignites a pilot flame, when the ground through the flame is detected, the gas valve will open and you will have heat. The flame sensing rod can be dirty and not detect the ground, about 90% of my calls are a dirty flame rod, you homeowners can clean that rod with a steel wool, sandpaper, or scotchbrite pad, may save a service call.
If the blower blows, and the sensor detects and proves that, the spark will start, if the pilot will light, if the flame rod is clean and working, the gas valve will open.
Now I have to say that it's been a long time since I have looked at my RV furnace, so I may be missing something, but the basics are the same.
Good luck. Ozz

Ozz · 02-16-2010, 05:50 AM

Here are good links for troubleshooting furnaces:
http://www.ducktec.com/furnace-trouble-shooting.html
http://www.rverscorner.com/articles/furnace1.html
http://www.marksrv.com/furnace_trouble_shooting.htm
http://www.rvforum.net/miscfiles/Furnace_Trouble-2.pdf

8.1al · 02-16-2010, 12:07 PM

The last one is very good

thor · 02-16-2010, 07:13 PM

hi just had the same problem with mine.when the blower comes on there is a litle switch that read the speed of the blower.if this switch does not see the right rpm off the blower then the furnace shuts down . this is telling the furnace not to send gas or light .on my 3400rl i had to pull the furnace out to get at this switch.i undid the terminals and cleaned them .that was all it needed.if you hook the leads back up and use a portable porpane tank off your barby you can test it before putting it back in or have it bench checked.

Ozz · 02-17-2010, 12:52 AM

good job thor, sometimes it is not a replacement issue. As I said the system is designed for safety, any loose or corroded connection will weaken the signal and lock out. Low voltage is a problem at times also.

8.1al · 02-17-2010, 03:35 AM

An accumulation of dust and dirt can affect the blower and the sail switch. I know it did on mine

BigSkys · 02-17-2010, 01:22 PM

OK we froze our buts off, the heater never did start up, and I could here the igniter trying to light it, I took the panel off and got to the heater, all the wires and gas is hooked up ok, I checked the gas supply to it, it is ok, so I got the unit all ready to come out of the 5er and bench check it this week some time, I then hooked the gas line back to it so I could have gas to the rest of the rv. We just got back from our long weekend last night. All I got to do now is take the gas line back off and disconnect the wires and out it comes. I will let you all know what I come up with. Thank you all for all your good comments and help. You are all a big help for the Dummy Newbie’s like me.

HughM · 02-17-2010, 02:57 PM

My problem was that the heater was getting propane but it blew cold air. Everything worked except one thing.
The propane orfice was clogged with....knats, lots of knats. Took orfice off banged it on tailgate and put it back on. Heater works great.
Hugh

Ozz · 02-17-2010, 04:03 PM

Good job Hugh

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