Furnace Blows Fuses
Dear RV Doctor:
I just purchased a 1993 RV. The heater works, but it blows fuses after about five minutes of operation. It has a 15-amp fuse, and I replace it with the same. Any ideas?
Steve Smithers
Bend, Oregon
Steve, you didn’t give me much to go on, but I can tell you this: Tracking down short circuits on an appliance is best performed while on a test bench. That way, it’s possible to literally see all the components in the sequence of operation.
A supply of propane is not required for this test, since it’s an obvious electrical issue. Only a 12-volt source is needed; perhaps a spare battery and a couple of test leads. Run the furnace by shorting together the thermostat leads. The electrical components in sequence will include the printed circuit board, the fan switch, the motor, the sail switch, and the high-limit switch. Inspect all the wires and their respective connections. Something is shorting out somewhere between any two of these components, probably to the metal frame of the furnace or its housing.
The RV furnace is really quite simple in its design. A long shot is that it could be an overheating fan motor. Look for obstructions or anything impeding the spinning of the squirrel cage. The 12-volt fan motor has an internal thermal cutoff to protect it if something jams the revolution of the cage, but over time, perhaps the fan motor developed an internal short. Not likely, but it is a possibility. If it works fine on the bench test, then the problem lies inside the RV somewhere between the power source, the thermostat, and the furnace cabinet. And your hunt, therefore, would continue.
Discolored Cord Contacts
Dear RV Doctor:
When I was unplugging my RV shore cord this past weekend, I noticed one of the fittings on the cable and one of the fittings on the RV connector were burned some and discolored. I did not have any trouble with electricity over the weekend, but I am nervous about the discoloration of these fittings. Do I need to replace my RV electrical cable? I bought it in 2005 and it’s always worked great. I just want to be safe.
Deb Gildersleeve
Atlanta, Georgia
It sounds as though there was a load (or two) in the “on” position inside the coach as you either plugged or unplugged from shore power at some time. That electrical energy easily can “jump” the gap — that short space created between the prong and the connection — just as you are plugging in or unplugging the cord, especially with current already running through it.
Always turn off the circuit breakers inside the coach or at the power source before plugging in and unplugging the coach. If the cord contacts are burned enough to show missing metal, or if the rubber around it is melted and distorted in any way, it’s probably time for a new shoreline cord.
You can easily remove the discoloration by rubbing the contacts with 0000-grade steel wool, or a fine emery cloth. Always keep those exposed contacts clean and bright. Overloading the circuits also can produce excess heat that can cause the contacts to discolor, just not to the point of losing some of the metal alloy.
Low voltage at the source can cause problems. I always recommend that RVers measure the voltage and verify the polarity of that voltage before plugging in (with the circuit breakers turned off), and again after the circuit breakers are turned on and loads have been applied.
Also, if you’re using an extension cord, be sure it is rated for the same amount of current as the shore cord (30-amp or 50-amp). And avoid using a very long extension cord for a short run. Voltage drop along the length of the extension cord can lower the available voltage, causing more heat. Before investing in a new shore cable, send me a high-resolution photo of the discoloration, if you can, and I’ll be able to tell if it’s necessary to replace it.
Curtain Call
Dear RV Doctor:
What is the best way to install a ceiling curtain track in our Coachmen Type C motorhome? It is a plastic track. Should I use screws, glue, double-sided tape, or some combination? Also, what size screws or type of tape/glue is appropriate? Any information would be helpful.
Barry Canovas
New York, New York
I’ve had success using 3M double-sided tape, in addition to screws. But this has a lot to do with the type of ceiling panel you’re attaching the rail to. If the paneling is relatively thick, you can probably get by with No. 6 flat-head screws spaced rather closely together. Remember, you’ll likely be yanking on that curtain, and some of the force will probably be downward. I’d say spacing the screws every eight inches or so should be fine. If the paneling is quite thin, you may need some hollow wall anchors or plastic shields to provide enough holding power. Perhaps you can punch a small hole inside a cabinet somewhere to see how thick that ceiling panel is.
I can’t remember the 3M product number of the tape I used, but looking at a 3M chart, 3M High Performance Double Coated Tape 9088 looks like it may do the trick. Predrill and then mount the track to the ceiling first using the double-sided tape. Then install the screws, taking care not to strip them in the paneling. As long as you resist pulling downward as you slide the curtain back and forth, you should be fine. It just takes a little awareness.