Furnace works; then doesn't; works again?

[VA-Apraisr]

2003 Fourwinds E450. Last trip to NY, furnace did fine all day but went to bed and wouldn't hold temperature and could hear blow turn on but ignitor won't fire, so turned it off. Just got it back from RV repair and they said they replaced the circuit board. Checked it before I left and turned on, but as soon as I get home, won't turn on. Kept running thermostat up and down but nothing. Using a digital Honeywell thermostat btw and it's almost new. Can hear the "click" each time I turn off/on so think that's ok. So, turned it off and back on and it fired up again. Got up to 70 degrees, it turned off, and won't come back on to keep temp at 70. I've tried it hooked to house power, batteries and generator....makes no difference. House batteries are at 12.9amp so shouldn't be an issue. Before I lug it back 40 miles to shop, any ideas from the "thinking men" on the board?

[bobndot]

VA-Apraisr wrote:
Yep.....thought about that too, Bob! I also boondock more than hookup, so it's rather important to me. Not sure what a new unit would cost but will ask. Mainly, I want to make sure they pulled it apart versus just put the board in and fired it up once. I think a trained monkey could do that.

:B Good luck , I hope it's a simple fix for you.

[VA-Apraisr]

Yep.....thought about that too, Bob! I also boondock more than hookup, so it's rather important to me. Not sure what a new unit would cost but will ask. Mainly, I want to make sure they pulled it apart versus just put the board in and fired it up once. I think a trained monkey could do that.

[bobndot]

With hourly shops rates at what they are today be careful as they pile on the hours to match the cost of a new unit. I understand the economics of it and hope you can easily resolve this, like a simple cleaning or replacing a switch.
It comes to a point when we have to think about buying a new unit opposed to taking stabs at repairing something 14 yrs old for something else to malfunction on it tomorrow. That will depend on the dealers honesty and level of skill.
Because I boondock in off grid places far from help in cold temps , I prefer to buy new things to lessen my chances for things to malfunction. I look at it as having 14 yrs of service out of it really isn't a bad run, especially the way things are made these days.

I'm talking about the furnace replacement not the whole rv.

[cdl2]

It might have a high limit switch that turns the furnace off.

[VA-Apraisr]

Going to drive it back and suggest they test all the suggestions provided. I wrote them down. Furnace came on a few time when switched on but next try would do nothing. Even replaced wall thermostat and still same thing. Just won't staying running to keep temp at 65 degrees. If it starts, it runs until hits 65 then will not automatically restart to hold temp. I asked them to service the system since it's never been done in 14 years and they just replaced the board and fired it up once and turned it off. I had told them what it was doing.....no one cares enough to follow directions nor guarantee their workmanship anymore. Will follow up. Thanks!

[C_B_]

This could be your problem.



I'm having the same problem with a Suburban furnace in my 2006 Cherokee.







After doing all kinds of testing we found this.





The tube that brings propane to the orifice has rusted on the inside.

Speck of rust blocks propane flow and furnace will not ignite. Clean out tube and furnace will work til another piece of rust plugs orifice again.

This must be happening a lot. the part from Suburban is on national back order.


C.B.

[bobndot]

VA-Apraisr wrote:
I've tried it hooked to house power, batteries and generator....makes no difference. House batteries are at 12.9amp so shouldn't be an issue.

The op said his batts are 12.9 volts not amps I assume and it makes no difference. Why would you think its a low battery ?

I think the answer is in that link I provided. However, it might be easier to drive the 40 miles and go back to that dealer.

[Yeti_plus]

I am in the check the battery camp, but not the 12 volt battery,. Check the battery in the digital t-stat. Even though you say it is a new stat the cheap batteries they sell with anything these days don't last long. And it is a lot easier to check t-stat battery than trailer battery.

[midnightsadie]

x2 you have a new board ,check out the battery system.

[ksg5000]

If your not plugged into shore power then what your experiencing sounds like your battery is getting low. Your heater only generates heat when the fan is running fast enough to open the sail switch (safety mechanism which much be open for the gas to flow) - and when your battery starts to run down the fan may energize but not run fast enough to open the sail switch. Just my 02.

[bobndot]

I think the board was a bad board, it happens often enough to think that.
If the tech thought that was the problem in the first place and he changed it, then it worked when you tried it, then stopped. I would think the new board is a bad board.
I bought a Dinosaur board for my last rv and was told they make a more reliable board. It might sound silly, but I carry a spare.
It's so easy to plug in a new board and most of the time it solves the problems with furnaces. At least doing that tells me if it in fact is a bad board or not, quick and easy.

The only other thing that comes to mind is the your new wall thermostat. I remember people having issues using the auto mode on digital thermostats where it caused malfunctions between the furnace and fan, igniter, and A/C. You would have to google that cause I don't remember the exact problems with that and I cant find my saved info on it.

read Old-biscuit and there is a link for more info within this thread

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28593590/print/true.cfm