When I decided to have central air conditioning installed into my home, I started doing some research. I didn’t want to make such a large investment without being knowledgeable about the equipment. I thought I had a pretty good idea of how an air conditioner operated, but I was wrong. The majority of cooling units are split systems, which consists of an indoor air-handling unit and an outdoor condensing unit. The indoor air handler houses a supply fan, a cooling coil, and the expansion device. The outdoor component consists of a compressor and a condenser coil. The air conditioner works to cool and dehumidify indoor air by passing it over a cold coil surface. The indoor coil is actually made up of rows of tubes that pass refrigerant through the coil. As the warm air passes over the indoor cooling coil, it heats the cold refrigerant and transforms it into a warm gas. The gas is then pumped from the coil to the compressor, and finally, the outdoor condenser. The heat is then displaced, creating condensate, as the refrigerant is condensed back into a liquid. The process is simply repeated over and over, creating a cooling effect in the house. The seasonal energy efficiency rating (SEER) indicates how effectively the air conditioner manages the cooling process. The higher the SEER rating, the more energy efficient the equipment, and the lower the operational costs. Units with a higher SEER, however, cost far more to purchase. I decided that it was worth a larger initial investment to trim down operational costs every month.