In 2010 the production or importation of r22 was limited for use in existing air conditioners but was banned for use in new equipment. Also in 2010, manufacturers of air conditioning units and heat pumps, abiding by the law, stopped making systems that use r22 refrigerant. The new r410a refrigerant operates at a higher pressure and the older equipment will not support its use.
The use of r410a in residential air conditioners was approved by the EPA after studies determined it did not affect the ozone layer. Regulations preventing it from being vented into the atmosphere remain in place as it has been proven to contribute to greenhouse gas.