Inside air conditioning systems is liquid/gas refrigerant. There are two types of this refrigerant available for use, R-22 (more commonly known as Freon), and a newer alternative R-410A.
An air conditioning system does not consume refrigerant, but reuses it. As long as there are no leaks in the refrigerant circuit, there is no need to ever add more refrigerant to an air conditioning system.
Although R-22 is an effective refrigerant, if it is released into the atmosphere it can contribute to the depletion of the Earth’s ozone layer. The EPA has mandated the phasing out the use of R-22. It is being replaced by R-410A.
As of 2010, manufacturer's are required to make all new air conditioners with R-410A. However, R-22 is still available for sale in existing pre-2010-manufactured equipment, and for use in servicing existing R-22 equipment. By 2020, R-22 will no longer be manufactured, but will still be recycled and available for sale.