These systems are by far the most common type of central air conditioning system currently being used. They consist of the condenser and compressor placed outside in a metal cabinet in one package. A separate evaporator is placed indoors within a segregated container, usually located in a closet or the attic. The outdoor unit provides the refrigerant to the evaporator, which then cools the air and pumps it down the network of central air ducts through an air handling unit.
Split central air conditioners are usually three times the size of an equivalent packaged central air conditioner. Splitting them in two makes the size much more manageable.