Fan Coil Unit (FCU) and Air Handling Unit (AHU) have a function to provide temperature and the humidity is in accordance with the controlled values The air duct is the route where the air that has been reconditioned is distributed to various parts of the building. The volume of supply air and return air will depend on the number of people and activities in each part of the building. FCU&AHU is generally used with chiller which is a equipment used to distribute chilled water. Which is a refrigerant for FCU&AHU.