In our local area, the summers are long, hot, and also seriously humid which makes air conditioning a necessity. In recent years, due to the improvement of cooling technology, air conditioning has become more affordable and now approximately 87% of American homes now rely on some type of air conditioner. The operation of a cooling unit is based on a chemical refrigerant which loops from inside the home to outside then back inside again, absorbing plus expelling heat while in the process. There are now two respected refrigerants used in residential cooling systems: R-22 plus the new more environmentally friendly R-410A. The refrigerant changes from a liquid to a gas quite easily which allows it to absorb heat in its liquid state, transform into a gas, then return to liquid, while expelling the heat it absorbed. A cooling system basically has four parts. There is an evaporator, a compressor, a condenser, and an expansion device. The component inside the home, where the refrigerant evaporates is called the evaporator. Fans blow air across the evaporator coils, where the refrigerant turns from being a chilly liquid to a hotter vapor. Because the air has the heat removed from it there is a cooling effect. The refrigerant passes into the compressor, which is located outside, where the gas is compressed into a higher pressure and temperature. From there, the hot pressurized gas flows over the condenser, which is also located outside. At this point, the refrigerant gas is returned back into its liquid state. The cooled-off liquid is then pumped back into the home, using the expansion device to regulate the flow of liquid refrigerant. The cycle repeats allowing the efficiency of refrigerant transforming from gas to liquid plus back to directly impact the cost of operation.