Package Unit
In a package unit air conditioning system the compressor, condenser, and evaporator are all located in one self-contained unit, which usually is located on the ground or a roof top. Package air conditioners are normally used for mobile homes, homes on a crawl space, and residential and commercial roof tops. Supply and return air ducts come from indoors through the home's exterior wall or roof to connect with the package air conditioner system.
Packaged air conditioners often include electric heating coils or a natural gas furnace. The most popular versions are package units for air conditioning only, air conditioning heat pumps, electric heat (for mild winter climates) and gas heat package units. This combination of an air conditioner and central heating eliminates the need for a separate furnace indoors.