This document discusses different types of air conditioning systems and their components. It introduces window units, split units, central air conditioning, and packaged units. It then covers the cooling cycle/refrigeration cycle involving the compressor, condenser, expansion valve, and evaporator. District cooling systems and chilled beam systems are also introduced as newer technologies. The coolant used in air conditioning systems must be non-toxic, non-explosive, non-corrosive, and have high electrical resistance while effectively lubricating components. Common coolants mentioned include R-22, R-12, and R-11.