Freon is a brand name of gases made by stripping the hydrogen atoms off the natural gas molecule and replacing them with fluorine or chlorine atoms. This substance works by absorbing latent heat when it changes state the same way water does when you sweat. When a liquid changes state to a gas it absorbs heat that cannot be measured by a change in temperature. For example, when water changes state it either releases or absorbs latent heat. When ice melts it absorbs heat which is why it cools your drink; when water turns to a vapor it absorbs 960 btu's per pound of water and vice versa. A refrigerant can be any liquid used to absorb heat and move it. When freon is sprayed into a coil at a low pressure it boils into a gas absorbing heat then in the compressor it is pressurized, raising the temp and the hot gas it sent into the condenser coil where it loses heat to the outside air or to water if it is a water-cooled coil which again turns it into a liquid to start the cycle again. Usually when someone says a unit needs Freon they are mistaken-it usually needs cleaning because the most common problem is dirt blocking airflow. DrTom4444