A refrigerant in air conditioner is a natural gas or chemical blend used in the refrigeration cycle of air conditioning systems and heat pumps. During the refrigeration cycle, it changes from a gaseous to a liquid state and back to a gas again.

Refrigerant is used for its ability to change from liquid to gas. During the refrigeration cycle, the refrigerant absorbs heat inside and releases it outside (or the other way around in the case of heat pumps, which can reverse the cycle to provide heating).

The most common refrigerants used in air conditioning systems are R410A, also known as Puron, and R32, which was developed primarily to reduce the impact of hydrocarbons on the environment.