The EPA has specified that newly manufactured air conditioning systems will not contain R-22 refrigerant. R22 is damaging to the ozone layer and Ozone-friendly refrigerants are now used in units manufactured after January 1, 2010. R-410A is the most common replacement and is found in most new units. While R-410A is used in most new systems, it may not be used in existing systems designed to use R-22 refrigerant. Design specifications to handle the increased pressure and cooling capacity of R-410A are required.