In simple terms, refrigerant is a fluid that is circulated through a refrigeration system and goes through a process of thermal exchange to move heat from one place to another. This fluid is converted into low pressure gas and removes heat from indoors to providing cooling indoors in an air conditioner. It is contained within the coils of an air conditioning system. If we start in the compressor, refrigerant is converted to a high-pressure gas, which causes the temperature to rise. The hot, high-pressure gas then moves to the condenser where it is cooled and converted into a hot liquid. A fan blowing over the coils dissipate heat of condense. The hot liquid refrigerant moves through an expansion valve where it cools to become a 2 phase (gas & liquid mixture) gas. Once it is cooled, the cold refrigerant moves into the evaporator where it cools the room air and as it evaporates into a gas. It draws heat from the space and takes that heat back into the compressor. This process is repeated as the air conditioner continues to cool a house or building. The process seems complex but it is applying some basic thermodynamic principles to allows air conditioners to keep us cool.