Why freon gas compressed in compressor in ac?

Air conditioning works by having the refrigerant undergo changes of state of the refrigerant between a liquid and a vapor, and also through heat exchanges, where heat is absorbed by the refrigerant, and is then exchanged to the ambient air both in the condenser and evaporator. In order for the heat absorbed by the refrigerant to be able to be exchanged to the ambient air, the temperature of the refrigerant must be significantly higher than that of the ambient air. Compressing the refrigerant into a high pressure vapor (which the compressor does) increases the heat of the refrigerant, as, when under high pressure, the molecules rub together more frequently, thus generating additional heat to the heat already absorbed by the refrigerant. This facilitates the heat transfer necessary for the proper performance of an air conditioning system.