Refrigerant is a chemical that produces a refrigerating effect in the a/c system. This chemical is otherwise known as Freon. R-22 freon is used in approximately 95% of the older air-conditioning units in the U.S. today. The newest type of refrigerant recently released and is now widely used is R410-A. This refrigerant has been introduced in some of the highest efficiency units available for residential and has become the new minimum requirement in new systems. Most companies sell the R410-A systems now, it also requires a separate more technical means for maintenance and handling compared to R-22 freon. Within the next few years, R-22 freon will not be available as a resource any longer. The cost of trying to obtain it has and will continue to rise. Although other alternatives have been made available, such as R407c, R-22 systems are being phased out rapidly in the near future.