In a packaged 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, which is usually located outdoors.