Troubleshooting, Repairing, and Replacing an RV Camper Power Converter
Many RVs and camper trailers use a power converter to operate the lights, refrigerator, vent fans, and perhaps the thermostat on the heating system. The converter uses the 110-volt AC power from the local power source and transforms it into the 12-volt DC these items require.
This article is intended to help you troubleshoot many converter problems and to repair or replace the unit if need be. Since there are different makes, types, and sizes of converters, this article will deal with problems common to most models.
Although electrical knowledge is helpful, it is not necessary in order to be able to check the power converter or to repair or replace it.
For more basic information on how the electrical system on your RV works, see this article.
Always unplug the RV from the 110-volt power supply before attempting to repair any electrical components of the power converter unit.
Classic Travel Trailers
Types of Converter Problems
In most cases, a malfunctioning converter will just cease to function with the result being the total loss of power to any 12-volt DC fixtures or controls. In other cases, the converter will produce power, but not enough to run the 12-volt DC electrical system.
But until the onboard 12-volt batteries are exhausted of their charge, the problems will not become apparent. The power converter is supposed to maintain a constant charge on these batteries, supplying variable voltage depending on the amount being drawn from the 12-volt DC system.
Remember that the onboard batteries must be in good shape and able to hold a full charge. One bad battery will draw power from the other good batteries and will eventually cause them to fail also.
To check the batteries, it is necessary to fully charge them and then disconnect them from the others to check their recharging abilities. Check them with a multimeter, after they sit awhile, to determine if one or more is losing voltage.
Troubleshooting the RV Power Converter
The first step in determining the problem is to start from the beginning—that is, the point where the 110-volt AC supply enters the RV power converter.
- With the RV power supply connected, check the voltage at the point it enters the converter. It should be between 108 to 130 volts. Anything in this range is okay!
- The next order of business is to check the voltage where it connects to the 12 volt DC breaker box. It should be 11-13 volts to operate satisfactorily. Anything less indicates a bad power converter.
Once we know the problem is a malfunctioning RV power converter, we can check the inner components of the unit.
1. Power Converter Fan
RV power converters use a small fan to keep the electrical components cool while the unit is charging. It should be possible to hear the cooling fan running intermittently while the converter is in use (the fan may operate only when the temperature reaches a certain point).
This fan normally uses the 110-volt AC line voltage to operate. If the voltage to the fan is in the correct range, the fan itself is probably malfunctioning. Replacing this fan is normally an easy project, but finding the right fan might be a problem. Note the make, part numbers, voltage, and any other information on the RV power converter fan motor, for use in obtaining a replacement online.
In some cases, a different make and model may be substituted as long as the voltage and amperage are similar and the motor fits in the space. If the voltage is not getting to the cooling fan from the thermostat, a replacement thermostat is needed. These can be found online as well.
A thermal sensor is used to switch the cooling fan on and off, depending on the operating temperature of the converter components. Make sure the current is getting past this sensor and to the cooling fan before buying a new fan.
If the fan itself, as opposed to the sensor, is not malfunctioning, you should be able to jump the sensor and cause the fan to operate. If this is the case, replace the sensor with one of equal temperature rating.
2. Resistors and Circuit Board
Some power converters rely on a resistor to control the voltage to the onboard batteries and the 12-volt DC system. In some models, the resistor is riveted to the converter box. When checked with the multimeter, the resistor should read from 3 to 13 volts, depending on the present charge of the battery, and which onboard 12-volt lights, fans, and other accessories are being used. If your batteries are not being fully charged, the resistor is often the culprit.
It may be necessary to disassemble the converter box to access this resistor. Be careful if the circuit board requires removal, or you may damage it. Drill out the rivet and replace with the correct replacement resistor.
If the exact replacement part is difficult to locate, you may find a satisfactory replacement at an auto supply store because this type of resistor is used in many automotive applications. As long as the values are the same, almost any 12-volt DC resistor should work. Once this resistor is replaced, the onboard batteries should stay charged with the proper amount of voltage.
Sometimes it’s just better to bite the bullet and buy a new converter, especially if you aren’t the DIY type of person or just don’t have the time to chase down parts. But actually, it isn’t all that costly to install a new power converter. Installation is very easy too.
Progressive Dynamics Inteli-Power converters are fan-cooled and deliver clean, dependable 12-volt DC power to the lights and other appliances in your motorhome or camping trailer. Choose from 45-, 60-, and 80-amp models to fit your particular RV power requirements.
If you’re thinking of replacing the 12-volt DC breaker panel, or updating an older motorhome or travel trailer, the Parallax 7345 Power Center combines the power converter with a reliable breaker system for dependable, clean 12-volt DC power to supply your RV. (For more on breaker systems in RVs, see this article). Parallax also provides 45- and 55- amp converters and breaker panels separately.
A good 12-volt converter system can make or break a camping trip. Learning to repair and understand how the system works will eventually pay off on one of these occasions. Good luck!