3. Split system. This type of air conditioner comprises of two separate parts: the indoor unit and the outdoor unit. The indoor unit, installed inside the house, is made up of the cooling coil or evaporator and cooling fan while the outdoor unit usually found outside the building comprises of the condenser, compressor and expansion valve.
4. Central air conditioning system. This type of air conditioning system is used to cool entire house and buildings. It has the capacity to deliver tons of cooled air to all the parts of a building that needed cooling. This system is also the most difficult to implement as it requires careful planning and installation of networks of air duct system to all the rooms and areas of the building.
The above-enumerated types of air conditioners are the ones that are commonly used. There are other kinds coming out from the market but they are essentially just a variation of one of the foregoing types.