THE ANATOMY OF AN RV FURNACE

It’s been an unusually cool winter in the Southwest. Even the desert floor has been high 50s to mid-60s during the day and low thirties and sometimes into the 20’s at night. For us this has been a shake down cruise this winter. When we traveled full-time in the 70‘s and 80‘s , we discovered everything we needed to do for comfort and convenience and continually readied the land yacht to sail. Preparing for this trip I added a solar panel to the roof and bought a new deep cycle battery. That has worked out so well I plan to add at least one more and a couple solar batteries. We only hook up to electricity when we have had a few days of little or no sun, which is seldom. Owning an RV is a constant precautionary maintenance job. Many little “puckersnatches” arise that need attention. This year it was the forced air furnace--it worked but only when it felt like it. It was finicky, which would make me cranky. I had pulled the furnace once before we left home to inspect it. It looked fine and worked fine. Once we hit the road, it occasionally wouldn’t light and I would have to diddle with it until it fired up. By midwinter I would fiddle and diddle and it still wouldn’t fire up. That is when I became an uncertified RV furnace mechanic. I got all my training on Google. I read everything I could and kept pulling the furnace out and troubleshooting all the suggestions I was discovering on Google. I couldn’t seem to solve the mystery of the cold air furnace. I thought about taking it to a certified RV mechanic but everyone I talked to seemed to know less than I did about them. Most of them just keep throwing new parts at problems until they work. They also want you to move out of your rig for a few days while they scratch their heads (at a $100.00 an hour) and come up with a solution. 

I discovered working on an RV furnace is not brain surgery (even though I would like to try that someday too) First, you see if you have sufficient power to the furnace. The blower kicks on, which blows enough air on a sail switch to turn it on. That sends power to a limit switch. If everything is working up to that point you have a furnace that blows cold air. I HAD A LOT OF COLD AIR. After that it gets a bit more complicated. There is a control board that makes the guts of a computer look uncomplicated. I don’t understand transistors, and little soldered things, so I pulled the furnace and had it bench tested at a propane dealer. He said the sail switch was dirty and that it fired up on his bench. That misinformation set me back twenty bucks and a week of googling. It didn’t make sense. If it fired up on his bench it should fire up in my motor home. More cold mornings. 

Finally, I pulled the furnace again and hooked up my own bench test on the floor of the motor home. I guess you would call this a floor test. From the limit switch to the gas valve I had no power. Between the two sat the transistor laden control board. It had to be the board. The propane bench tester must have scammed me. It couldn’t light if the board was fried. I decided to gamble. I ordered a new board online and had it shipped to Oliver Lee State Park, in New Mexico, where our friends were camp hosts. When it arrived I pulled the furnace one last time and wired in the new board. I put it all back together, prayed the prayer of RV furnace technicians, and switched on the thermostat. Bingo, Bango, Bongo. NASA we have ignition. I get such a warm feeling all over when my furnace kicks on. 

So the moral of the story is this. My fix cost about a hundred bucks and lots of googling. If you have to go to a certified RV mechanic, you might just as well buy a new furnace @ $700.00, because those jokers are going to cost you nearly that much anyway. It is all part of the RV lifestyle. If you have a furnace problem just call me. I have been thinking about starting the Doctor R.V. Shrink Diagnostic Service. I can come over to your rig and listen to your woes. Once I look the situation over, rub my chin thoughtfully, scratch my head and grunt a few undecipherable words, I charge you $25 and confirm for you that you do have major problems. Ya gotta love this RV business!   --Keep Smilin'