What is the definition of a package AC unit? A package air conditioning unit is an all-in-one air conditioning system usually used to cool larger areas such as commercial and industrial buildings. It typically consists of an outdoor condenser unit and an indoor evaporator coil that is connected to ducts. The package AC unit is designed to provide both heating and cooling capabilities in a single unit. It is highly efficient and is often used in combination with other heating and cooling systems. The main advantage of the package AC unit is that it can be quickly and easily installed and is able to provide both heating and cooling to a large area. It can also be more cost effective than other systems. However, it is important to remember that the package AC unit is not suitable for every application and must be carefully selected to ensure that it is able to meet the heating and cooling requirements of the building.