Instead of a refrigerant, recreational vehicle (RV) refrigerators use heat to catalyze a chemical reaction. Three-way refrigerators get their name from being able to operate on gas, DC (battery) and AC (household) current
During gas operation, RV refrigerators use a small propane burner to generate heat. In AC and DC modes the refrigerators uses an electrical heating element to start the chemical reaction.
The heat produced by the gas burning or electrical current causes hydrogen gas and an ammonia-water solution to circulate. As the chemicals circulate throughout the system, heat is removed by continual condensation and evaporation, cooling the refrigerator.
RV refrigerators must be kept level for the chemical reaction to work effectively. If the units are not level an air bubble can develop, preventing the solution from circulating and cooling the unit.
- coach, trailer image by Greg Pickens from Fotolia.com