Which of the following is NOT covered by the EPA 609 certification?

The correct answer is that handling of domestic air conditioning systems is not covered by the EPA 609 certification. This certification specifically focuses on mobile automotive refrigerant handling, which is distinct from the procedures and techniques associated with domestic air conditioning systems, typically governed by other EPA regulations and standards.

The EPA 609 certification encompasses areas critical for technicians working on automotive air conditioning systems, such as refrigerant recovery procedures, refrigerant leak testing techniques, and certification maintenance requirements. Each of these aspects is vital for ensuring proper handling and compliance within the automotive sector. However, the handling and servicing of domestic systems falls under different regulatory frameworks and is not part of the training or requirements for the EPA 609 certification.