The certification of mobile air conditioning unit technicians is required by U.S. law under section 609 of the Clean Air Act of 1990. Automobile air conditioning units produced before the introduction of the CAA commonly use chemicals, including CFCs and HCFCs, that damage the protective ozone layer in the Earth's atmosphere.
Automobile technicians who are responsible for reclaiming and recycling R12 refrigerant, known by brand names, including Freon, must be certified by the EPA. The sale of R12 substitute refrigerant is prohibited to individuals not certified under section 609.
To become certified under section 609 an individual must complete successfully an examination administered by an EPA approved organization, such as the Mobile Air Conditioning Society. The cost of home study materials and the examination offered by the MACS in 2011 is $20.