Keep cool and comfortable

How to maintain your RV air conditioner—and avoid breakdowns

by Reg DeYoung

During the hot summer days you may realize how fortunate you are to have an air conditioner and really enjoy the personal comfort it provides to the RV interior. I will provide a basic understanding of how the system works and some tips to ensure your air conditioner operates efficiently.

How they work

RV air conditioners are a compressor—type unit that work on the same principle as a residential unit. They are relatively lightweight and very durable in their ability to endure the vibrations of the highway. Like an RV refrigerator, an air conditioner works by removing heat from the air and transferring it outside. The basic parts of an air conditioner are a sealed or closed system consisting of a compressor, a condenser, an evaporator and a series of copper tubing to connect all of these units together. In addition to these components, there is a motor with two fans which have two functions: one is to move air across the condenser and the other moves air across the evaporator.

The evaporator absorbs heat from the interior of the RV and vaporizes it, then the refrigerant—which is an R—22 mix—is then routed through the condenser where the heat is removed and transferred outside of the RV.

The compressor is the component that pushes the refrigerant through the system and is driven from the electrical circuit provided to the unit. An air conditioner also cools the interior air by working like a dehumidifier—this dry air is always more comfortable than humid air. The moisture in the atmosphere is drawn through the evaporator and condenses into water droplets that you will sometimes see dripping from your RV's roof when the air conditioner is operating.

Tips and tricks Recently at our shop we had the opportunity to be further educated on these systems by Joe Croke, owner of Big Mountain Services in Canmore, Alberta. He spoke about reasons why these units fail and also informed us of some preventative tips to ensure your RV air conditioner will be there when you need it and how to minimize breakdowns.

First, I advise you not to open or breach this closed system as a do—it—yourself project—there are very high pressures associated with the discharge line from the compressor. Also, there are capacitors used in the electrical part of the system that can cause serious injury if tampered with. It is best to leave the troubleshooting or repairs to the experts and avoid potential hazards.

One common problem is operating your air conditioner on high when the outside temperature drops below 75º F or 24º C. This will cause ice to build up on the evaporator coil, which will reduce the air flow and form a blockage. If ice-up occurs, turn off the air conditioner and allow the coil to defrost before putting the unit back into service; also, if the filters are dirty, air flow will be further reduced and will form frost on the cooling coil.

Another common problem is overheating caused by low voltage. An air conditioner needs to have 103 to126 volts AC to be in the proper operating range. If the voltage is too low, the current will rise and this abnormal heat condition will engage the thermal—overload device and the compressor will shut down. This is especially problematic if you operate your AC on an undersized extension cord or in a serviced RV site that is being over—loaded because many users are on that circuit.

There are some options available for your air conditioner to give it an added purpose for your RV. You can add a heat strip, which will help warm your RV on a cool morning. The thermostat is set to the warmer setting and the fan will circulate the air generated by the heating coil. Also, you can purchase the heat pump—type unit which will warm your RV up by removing the heat from the outside air and transferring it into your RV. This system works best in air temperatures above 40º F or 4º C-and both systems will not replace the higher BTUs available for your RV furnace during the cooler months of the year.

An area that can be a problem is water leakage into the RV from the air conditioner. When the AC is installed, there is a sponge rubber gasket that is compressed to help seal the unit and provide a gap between it and the roof covering. It should be at least half an inch in width to provide the best seal—the gap allows the water from the operation of the system to drain away from the RV as mentioned above. In my experience, I have seen an AC unit that was completely sealed around the perimeter of the base, trapping water inside the base pan and running directly inside the RV.

If you are concerned about the present operation of your RV air conditioner and want a quick and easy test to determine if your unit is working properly, you can try the following tip. First, place a thermometer in the outlet grill or the closest duct and record the temperature, then move the thermostat to the air intake and record that temperature reading. If you subtract the reading at the intake grill from the outlet grill, the proper operating system will have a temperature differential of between 18 and 22 degrees.

All air conditioners will have breakdowns, especially if they are going full—time and on a hot summer day or night. However, by reading the operating manuals provided with the AC and doing your best to help the unit run as effectively as possible, you can prevent costly repairs and have an enjoyable RV vacation.

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