I recently purchased four LED night-lights at Walmart and installed three of them in my 2002 Monaco Diplomat motorhome. One recent evening while I was away, the generator in the coach ran intermittently for about four hours; the run time and off time were about equal. On returning home, I discovered that all three night-lights had stopped working. I opened them and found that a 100-ohm resistor had failed in each one. I found the value by looking in the light I hadn’t installed. I replaced the resistors, and each light worked fine.
Why would anyone spend that much time on a $1.50 light? Well, when you’re retired, you sometimes have a lot of time on your hands. Anyway, I’m satisfied that starting and stopping the generator caused the failures. I’m not so much concerned about the lights but rather other electronic equipment connected to the generator. Do you have any idea what might have happened, and what could I do to prevent the problem in the future?
Bill Marcum, F156820
Paducah, Kentucky
The voltage and frequency output of the generator may be the issue. If the voltage or frequency is too high or too low, it may have a negative impact on the lamp control circuit. This could damage other sensitive equipment on board, such as computers or printers. You’ll have to measure the load/no load voltage and frequency to be sure. Of course, the problem also could be the design of an inexpensive LED lamp. But having those load/no load voltage and frequency numbers would provide better direction.
I have a 2007 Holiday Rambler PDQ motorhome with a Cummins ISL 400-horsepower engine. The dash air conditioner runs great for about 20 minutes, then slowly quits. After I put it in the “off” position for 20 minutes and start it again, it runs fine for 20 more minutes. When the selector is on full heat and the vent position is selected, the unit produces heat, but it stops running after 20 minutes. I have replaced the compressor and all air conditioner lines from front to back. Also, a Freightliner dealer found shorts in a couple of wires and those were replaced. I still have the problem.
Douglas Lederman, F448319
La Quinta, California
From afar, this is just an educated guess; it would appear that the common part is the fan — either the fan motor or the fan wiring or the fan switch. Perhaps a reader has experienced this issue and can share information. Also, the following is what a member of FMC’s Technical Advisory Committee had to say:
“This sounds like it might be either a faulty resistor block or wiring fault causing overheating. If this unit utilizes a resistor block to limit the fan motor speed for the different fan settings, it may be overheating. Otherwise, the wiring may have been altered for some reason, or the wiring is otherwise damaged. Damaged wiring on a blower motor acts as a variable resistor that will heat up over time, increasing the resistance. Or, of course, it could be the fan itself. I can tell you it has nothing to do with the A/C subsystem.”
We plan to tow a car behind our 29-foot 2017 Newmar Bay Star Sport. What is the maximum car weight we can tow without using a supplemental braking system?
Jim Nelson, F463985
Escondido, California
First, FMCA does not recommend flat towing without a supplemental braking system, regardless of the various weights involved. Your motorhome’s service brakes are designed to work properly with weights up to the gross vehicle weight rating (GVWR). But the gross combination weight rating, or GCWR, which is the combined weight of the motorhome and towed vehicle, assumes that each vehicle has its own braking system.
For safety’s sake, please investigate supplemental braking systems. The October 2017 issue of FMC contains an article to help get you started.