Furnace not heating.

[HamRad]

Some of you may remember that we camped at the Grand Canyon after the Spring National Rally in Tucson. At that time of year it is still relatively cold. The first night about 4 am the furnace quit.

Thinking my propane tank need to be switched I checked it but sitll had a full tank. So I assumed the control board had gone out on me. We were planning on taking care of the problem when we got home. The hip problem took over my life and nothing got done on the trailer.

So now that I'm recovering I contacted my brother who was able to come down and work on the furnace. Do any of you know how hard it is to get the furnace out of it's little cubby hole? So we get it out and take off the control card and head for the RV parts place. Of course they don't have the part. So we go to another place. They also don't have the part BUT they do have the mechanic come up and talk with us about the problem. He says we can test it and tells us how. So we get back home and my brother goes about checking it. Well he gets a nice shock while testing. If you're testing this thing don't grab the igniter capacitor! You get a pretty decent shock.

So the board checks out as "good". So what is wrong? Why won't it fire up? As my brother is looking he sees a wire that does not look right. It is flat! It should not be flat. So he fixes the wire and hooks everything back up and slides the furnace back into its cage. Making certain to not stress or flatten any wires. Slides the unit back in its cubby hole and hooks up the propane and all the wires.

He fires the furnace up and it starts producing heat! It works. How nice! And it saved between 140 to 160 bucks. Not too bad.

So hopefully we won't freeze when we go to Q this year.

Next project fix the galley tank leak! Next week!

HamRad

[DONnANNIE]

Hi Dennis,

Glad you got it fixed and saved bucks to boot.

You mentioned testing the control board. How did you do that? Is there a list of instructions?

Leaky galley tank - damn, it's always something.

Glad your hip is coming along - mine is too.

[HamRad]

Don,

My brother did the actual testing. It just involves using your multimeter and discovering where the power is going. I'll get him to list out the step by step process. It is very simple once you get the board out.

And, yes, it is always something.... but wouldn't have it any other way.

I am walking unaided now about 50% of the time. The rest of the time I carry the cane and use it mostly just for balance. The residual pain in the hip is slowly getting better every day. It just seems to be really slow. But I'm to the point where I think I could make it at least half way around the circle at Lake Siskiyou. So I still have a ways to go. I'm hoping that by May I'll be doing the circle with little or no problem. Maybe we can have a race. Just kidding. I'm doing nothing to jeopardize the progress I've made so far.

Sure glad we got the furnace going. Boy would I have been ticked if I'd bought a new board and installed it and the thing still NOT work! So if you have a furnace problem check out each and every wire and connection. Make sure none of them are under any kind of stress. That can cause a short and the system will revert to its safety routine. We were just lucky this time. I'm amazed he even saw the wire was damaged. Of course it probably helps that he works on electric stuff all the time!

OK..... see you later.

Denniks

[simonsrf]

I think you just carry that cane around to keep the wiennie dogs off your feet.

Glad to hear that both you and Don are on the mend!

[mtheo]

Glad you got the furnace fixed, see you at the Q. Please post how to test the board.

[HamRad]

Several folks have asked about testing the control board.

1. Get the furnace out of it's hiddy hole.
2. Take the control board off the furnace.
3. Take the board to a RV Service place. They should have a testing device. They will simply plug the board into the testing device and the little lights will tell them what the problem is.

CW did not mention anything about testing the device. We learned this from visiting another long time RV place called Pennsingers. Unfortunately their tester was for older versions of the control board and would not help us. But he did tell us how to test.

So you take the control board back home.
1. Plug it into a 12volt power supply.
2. Then you look for power coming thru the various other circuits.
3. In this case the igniter has wire running to the top of the device.
4. Take that wire and hold it a fraction of an inch from the plug in place on the igniter device. Sort of like testing a sparkplug for firing.
5. If you get a spark then you know your control board igniter is good.

The problem was my brother was holding the board in one hand and the wire in the other for testing the igniter. He says it was a "shocking" moment! I didn't see it but I'll take his word for it. He did offer to "show" me exactly how to do it but being older and wiser I declined his offer. So as soon as he knew he had good power to the igniter he knew the board was OK. At least that part of it. And since that part will only work if the other parts are working correctly we assumed the board was not the problem.

As he was looking at reinstalling the core into the furnace shield he noticed the smashed wire. It was getting squished between the shield and the core. It was grounding out the board preventing the igniter for working. Fixed the wire and made certain it worked and was not getting smashed again and then reinstalled the furnace. While he had the furnace still out he did check the gas solenoids. He determined they worked by having the board installed and powered up. At the same time he blew into the valve to simulate the pressure needed from the propane. He could hear the device working so knew the valve was not the trouble.

Then he put the thing back together and buttoned everything up. Also reinstalled the intake and exit pipes that go thru the wall. Re caulked that and came back in an fired up the furnace. It worked like it should and has been doing so since.

I realize I have done a very poor job of explaining the testing process but it's the best I could do. If you are mechanically inclined you will probably get enough info to know what we did and can repeat it for your situation if necessary. If you are not so inclined (like me) then you get someone else to do it for you.

Bottom line is that it works. What we learned:
1. We know it is not always a bad board.
2. We know it is difficult in our situation to get the furnace in and out.
3 But we also know much more about how it works.

As a side note. We discovered some insulation partially blocking the vent access at the furnace. Now that that is removed we get a better flow of air out the vents.

4. We also know that the wiring is now not likely to be crimped or smashed and cause a problem.
5. And best of all we get heat when we turn it on and it goes off when we tell it to!
6 And we saved whatever it costs for a new board. Somewhere in the neighborhood of 130 to 160 dollars.

Dennis

[Ozz]

Dennis, I have found that the simple act of taking all the wires off when you are testing circuitry, then putting them back on, 'Fixes' the problem. Sometimes it is a slightly corroded connection, sometimes it just amounts to a 'hard reset', by powering down. I often walk away from a repair job not knowing what I did to fix the problem. I just tell the customer it was a bad wire. Many servicemen will sell a few parts to the customer, bad or not, and collect a fat check. A circuit board will also fail, work, then fail down the road for no apparent reason. I have easily worked on over a thousand of them. Not an easy job, being a repair guy.
Glad yours is working.
Ozz