What is the definition of a multi split air air conditioning system? A multi split air air conditioning system is an HVAC (Heating, Ventilation, and Air Conditioning) system that uses multiple indoor units connected to one outdoor unit to provide cooling or heating to multiple areas or rooms. The indoor units are connected to the outdoor unit by small copper lines, which allows them to draw refrigerant from the outdoor unit and distribute it throughout the house. The outdoor unit contains all the necessary components to cool or heat the air, such as a compressor, condenser, and evaporator. The indoor units are able to control the temperature of individual rooms, allowing you to set different temperatures for different rooms. This type of system is great for homes with multiple rooms or areas that require different temperatures. It also can save energy by only cooling or heating the rooms that are in use, rather than cooling or heating the entire home. The multi split air air conditioning system is a great way to keep your entire home comfortable