RV refrigerators run by heating up a sealed cooling element by a gas flame or an electronic element. The cooling unit is mounted on the back and is a series of coils that are filled with a solution of ammonia and sodium chromite. When it is heated, this solution flows through the cooling unit, drawing the heat out of the refrigerator. When an RV's refrigerator doesn't cool correctly, it means the coolant isn't flowing properly anymore.
If it is not cooling on any fuel source, it indicates a problem with the cooling unit. You can test this by fueling the cooling units. Be careful; it could be extremely hot. If it is running correctly, there should be around the same amount of heat in the center of the absorber and boiler. Sometimes vacuuming off the coils helps to cool it down some. If the cooling unit gets a leak in it, you will smell ammonia right away.
Most of the malfunctions of an RV's refrigerator is from blockage of the cooling unit. Any blockage will cause the flow of the solutions to slow or completely stop, preventing it from running. Most often the blockage is caused by the unit being run when it isn't level. The refrigerator relies on gravity to help move the solution throughout the system once the heat source has pushed the solution to the top. Not being level will bring this gravity flow back down, causing the solution to crystallize and get lodged. Tipping the unit upside down might be a temporary fix, or you will have to replace the cooling unit, but then you might be better off replacing the whole refrigerator.
