It’s NASCAR time in Bristol, Tenn., and I am parked outside the paddock where the drivers’ buses are sequestered. About 30 minutes ago, the owner of one of the buses called to ask if I knew how to check the compressors on a refrigerator. Having stared more than a cooler or two in the face, I assured him it was not my first rodeo and signed on. As the task was explained to me, he had a specialist locked, loaded, and at the ready to fly in and install two new compressors. My job was to assure him his considerable out-of-pocket expense was justified. So, I waited.
In not too many minutes, the driver (not of the race car, but the bus) arrived via golf cart and escorted me through security. Now just so we are all on the same page, I run a mobile RV service for RV owners, along with several large and small RV dealerships. Some days I work out of my truck, others I spend the day on a dealer’s lot. I service towables and motorhomes; conversion buses almost never. So why did I have the audacity to think I could troubleshoot an appliance I had not yet seen? For the same reason I think most motorhome owners can learn to work on many of the systems in their own coaches. Most motorhomes are the same; they just come in different flavors.
Now back to the story. Finding myself in front of a motorhome and not knowing how to open the pneumatic door was a bit disconcerting, and things were not looking a great deal better when the alleged problem child turned out to be a Sub-Zero double compressor household model refrigerator, ensconced in marble. However, here I was and there it was, so I needed to do something. What I decided to do was approach this problem just as I would any other; try not to panic and keep it simple. Fortunately, the driver knew how to open the door to the bus, so I was off to a good start.
The first step in any troubleshooting scenario requires the designated fixer to assume nothing about the task at hand. That line of thinking meant the refrigerator may not even be the guilty party. Time to interview the witnesses and this is what I learned. The breaker feeding power to the refrigerator had tripped and could not be reset for more than a second. Since every problem has to be verified, back outside I went and into the compartment with the breakers and fuses. Resetting the breaker was a waste of time. It snapped open instantly.
Now, knowing what I was up against, I began by asking myself this simple question: Is the breaker tripping because of the refrigerator or is it tripping for some other reason? If I could rule out the refrigerator, the compressors could not be the problem and my work was finished. The simplest way to resolve this issue would be to unplug the fridge and try resetting the breaker, but the refrigerator was built in and the plug was behind it. I needed a simpler plan. Disconnecting the power cord connected to the refrigerator was relatively simple as all the connections were exposed at the base of the fridge. I disconnected the cord, then I went back outside and reset the breaker. The breaker tripped, just as before.
Knowing now it was the circuit and not the refrigerator, I called the bus owner and told him to keep those compressors on the runway. The refrigerator was off the hook. Two weeks after the race, the bus driver called me to say the wall receptacle had a short. Grunt work to gain access to the receptacle, but technically not a very difficult repair.
My purpose in this example is not to explain how to troubleshoot Sub-Zero refrigerators. I likely will never see another, nor will most reading this. My goal is to suggest an approach for troubleshooting any problem in your motorhome. For, you see, the difference between a technician and a parts-changer is not tools, service manuals, or even experience. The difference is whether you use a step-wise approach to answer a question or simply throw parts at the problem in hopes it will go away.
If you have read this far, I am guessing you have done so either because you already work on your own motorhome, you would like to start working on your own coach, or you are simply hoping to pick up an idea or two to save some money. Let’s do the “save money” part first.
In my experience, if owners would learn to use their components correctly and regularly, they would eliminate at least 25 percent of their service costs. Like the human body, mechanical things, of all stripes, resent being stored and do much better with regular exercise. In addition, many motorhomes now come with a plethora of switches, lights, gauges and control panels. Operating these things is not always intuitive and reading the owner’s manuals may prove interesting.
Getting back to troubleshooting — there are some things that need to take place before you begin and understanding basic electricity is first on my list. I’d estimate well over 80 percent of service calls have to do with something electrical. You do not need to be an electrical engineer, but, if you do not have a working knowledge of terms like voltage, amperage and resistance, you will be in over your head fast!
Next, you are going to need service manuals and I am often asked how to obtain them. Service manuals, by the way, frequently have diagnostic trees to help break troubleshooting down into steps. Fortunately, that is one of the least difficult things about troubleshooting. Most service manuals are available on the Internet. Simply Google the manufacturer’s name and the component you are troubleshooting. When working on a component for the first time, I pull up the service manual and either print it or download it onto my laptop.
How about tools? You need at least one good electrical meter for sure and, speaking dogmatically, a high-end clamp meter capable of reading both direct current (DC) and alternating (AC) current (amperage) and what is called RMS voltage is an absolute. In my book, this is a lifetime purchase, so forget the shiny wrenches and put your money in a quality meter. If you have never used a meter before, start by practicing on the parts of your motorhome that are working. Using your meter, you will be able to test virtually everything in your coach that uses electricity, often in a matter of minutes. Remember, electricity can be dangerous, so no circuit is ever tested live, unless the test requires it!
In addition to my clamp meter, my first-out-of-the-truck bag includes stubby and standard-size ratcheting screwdrivers with changeable tips, needle-nose pliers, an angle wire cutter, and standard pliers. Besides the tools, I have two leads with alligator clips on each end and a couple of pieces of wire in case I have to bypass something. I also carry an infrared gun for reading component temperatures. I have many more tools on my truck, but the ones in my bag are the regulars.
So far, I have purposely avoided focusing on a specific appliance because far too often folks look for shortcuts, or as one caller said to me not long ago, “I can fix it myself. I only want you to tell me what is wrong and what part to buy.” Here is an example of the approach I would use on a call to service an air conditioner. The problem presents itself as “when I set the wall thermostat to cool and turn the temperature down, nothing happens.”
The first step is making sure the air conditioner has both AC and DC power. The DC power is sometimes necessary for the controls. The generator or shoreline provides 120-volt AC power. This week, I found 97.5 volts at one campground pedestal, and at another coach I found 118 volts at the breaker, but only 45 volts at the air conditioner. Sometimes you don’t need to go to step two. Your service manual contains the power requirements for whatever model you are servicing.
If the power supply is good, I would check for power from the board at the ceiling to the rooftop unit. If I had power out of the board, I would move to the unit on the roof. If I did not have power out of the board, I would bypass the wall thermostat, which controls the board. If the rooftop unit started when I bypassed the thermostat, I would replace the thermostat.
If it didn’t, I would next focus my attention on the module board in the ceiling, most likely replacing it, after checking the connections at the board. The crucial feature is that I am answering a series of simple questions, and so far, all I have used is a screwdriver, my multimeter, and perhaps a small wire to jump thermostat terminals. You will find the procedures for everything I noted here in the service manual.
A final thought I would like to share with you. Troubleshooting in a motorhome, as with all problem-solving, means answering a series of small questions. The only time I fail to resolve a problem is when one of two things happen — either I don’t know what to ask, or I ask the wrong question.
Steve Savage is a Master Certified RV Technician who frequently writes for consumer and industry publications.