Any person who repairs or services a motor vehicle air conditioning (MVAC) system for consideration (payment or bartering) must be properly trained and certified under section 609 of the Clean Air Act by an EPA-approved program. 

All technicians servicing MVAC-like appliances must be certified. SERVICING MOTOR VEHICLE AIR CONDITIONING INCLUDES: repairing leak testing topping off air conditioning systems low on refrigerant, as well as, any other repair to the vehicle which requires dismantling any part of the air conditioner. 

The EPA 609 certification is required to: Service motor vehicle A/C systems Purchase small containers (under 20 lbs) of regulated refrigerants The Section 609 Motor Vehicle Air Conditioning Exam is an open book test. A score of 84% correct (42 correct out of 50 questions) is required to pass the exam.