Most RV refrigerators operate on propane as well as 120 Volt and 12 Volt electricity. Thus, they are more complex than the refrigerator in your kitchen. They also have to operate in a much harsher environment. Household refrigerators don’t travel thousands of miles at 70 mph while operating or when tilted several degrees. Therefore, RV refrigerators require more care and maintenance.
RV refrigerators, which run on propane and electricity, use the absorption principle. They require three basic things to keep food at the recommended 38 to 40 degrees F. These include (1) supplying the proper amount of heat to the boiler either by the propane flame or electric resistance heater to liquefy the refrigerant, (2) good air flow over the condenser fins and absorber coils in the rear, and (3) proper leveling since the refrigeration is circulated by gravity rather than by a pump. Indeed, except for control switches, there are usually no moving parts in these refrigerators.
It is important that the propane burner is clean by keeping out soot. To clean the burner after gaining access, gently knock the soot off and blow it away with compressed air or a can of liquid air. Inspect the spark gap for propane ignition. It should be about 3/16-inch wide or as called for in the instruction manual. If not, bend the metal, not the steel wire electrode, to set the gap. You might even invest in a spare igniter, especially if you travel into remote areas. Also use low-pressure, compressed air to blow out dirt and dust in the flue enclosure.
When your refrigerator runs on 120 volt AC current, cooling can be reduced because of low voltage sometimes found in crowded campgrounds. If the fridge is designed for 120 volts, 108 volts means 10-percent less wattage and only 90-percent power, which can be a problem especially on hot, humid days. The simplest solution is to operate on propane. Fortunately, RV refrigerators don’t have motors that can be damaged by low voltage and the electric heater will only operate less efficiently. Extended operation at high voltages can shorten the life of the heating element.
Too little, as well as to much, clearance behind the fridge can affect efficiency. If the clearance is over about once inch, air circulation by convention can actually bypass the coils. This can be cured by adding a baffle to force the air over the coils. Make sure any vents at the back of the refrigerator and on the roof are clear. You can install a fan in the rear to assist airflow through the condenser fins.
There is a debate as to whether it is a good idea to keep the refrigerator operating while the RV is not in use and particularly during extended storage. Leaving it on does help prevent mold and insects from finding a home inside. If left on, do remove everything, clear spilled food and check it periodically.
While most modern RV refrigerators will operate in non-level condition, it is best to level the fridge to within a couple of degrees. This can mean better operation and longer life. Since the absorption cooling process relies on heat and gravity to circulate the refrigerant proper level orientation is important. When moving down the road the motion prevents the coolant from pooling in the boiler and overheating. If the refrigerant doesn’t circulate when parked, overheating can lead to cooling unit failure.
Never use abrasive cleansers or pad when cleaning the refrigerator’s interior surfaces. Warm water, liquid dishwasher detergent and a soft sponge work well. Add a few drops of vanilla to the rinse water for a fresh and pleasant smell inside. Defrost the refrigerator according the owner’s manual. While frost build up will occur faster in hot and humid weather, if very frequent defrosting is needed, suspect a leaking door seal, or you are operating it at too cold a temperature.
Use the dollar bill test to check out the door gasket for leaks. Insert the bill between seal and door frame. Close the door and pull on the bill. If the bill can be pulled out without resistance, cold air is leaking out and the gasket should be replaced. Repeat the test all the way around the door gasket. You should clean the seal before testing, otherwise sticky food residue can mask a seal that can start leaking once it is cleaned, or be the reason for leaking. When cleaning, make sure to wash inside the gasket’s accordion fold. While the door gasket can be replaced, it is a complicated task that often results in a gasket that still leaks. A more satisfactory solution is to install a new door. Repair any small tears in the vinyl gaskets with vinyl cement, them test for leakage.
There are several things you can do to reduce the cooling load. Keep the door closed as much as possible and know what you want to remove before you open the door. Consider using a separate ice-filled cooler for frequently used beverages and cold water so the door isn’t opened too often. If possible, park with the refrigerator side in the shade, and open awnings to keep the interior as cool as possible. Start the refrigerator when it is empty, and a day or so before your trip. This, plus loading the fridge with pre-cooled items, greatly reduces the load placed on it. Let hot or warm leftovers cool to room temperature before putting them into the refrigerator.
Finally, if the refrigerator suddenly stops cooling, turn it off for one to two hours, re-level the RV, and turn it back on. Sometimes the flow of refrigerant can become "vapor locked,", Turning it off will allow the pressures to equalize, removing the vapor lock. Sometimes lighting the propane stove will a cure vapor lock too.