It depends on the age of your unit. If you have a home air conditioner that was manufactured before January 1, 2010, it probably uses a refrigerant called hydrochlorofluorocarbon (HCFC)-22 (also known as R-22). Because HCFC-22 depletes the Earth's protective ozone layer, EPA regulations are gradually reducing the production and use of this refrigerant. In fact, manufacturers can no longer make new air conditioners that use HCFC-22. However, HCFC-22 can still be used to service existing air conditioners.