R-410A has been the refrigerant of choice in residential and light commercial cooling systems since 2010, when federal government regulations mandated that new air conditioners and heat pumps could no longer be manufactured using R-22. Since then, the production of new R-22 has been slowly winding down and will stop completely at the end of 2019, although reclaimed R-22 will be available to service existing systems long after 2020.
While many of those R-22 systems have been replaced with R-410A units, a large installed base still remains, meaning that technicians will have to know how to troubleshoot and service both types of equipment for many years to come.