R-22 is the common name for hydro-chlorofluorocarbon (HCFC). R-22 has been used as a refrigerant by HVAC manufacturers for over 40 years; however, studies conducted over the past decade have shown that HCFC contains chlorine, an ozone-depleting agent. Consequently, The United States passed The United States Clean Air Act, stating that HVAC manufacturers must cease the production of HVAC equipment/products that use R-22 by January 1st, 2010. HVAC systems produced prior to January 1st, 2010, likely operate using R-22, and they can still be serviced; however, beginning January 2020, R-22 will no longer be produced—any units running on R-22 will have to be repaired using recycled R-22.