Which of the following repairs is considered a major one under EPA regulations?

The replacement of an evaporator coil is considered a major repair under EPA regulations because it involves handling refrigerants and the potential for significant refrigerant loss. Major repairs are defined as those that involve the removal of a refrigerant-containing component and can affect the system's sealed integrity. Evaporator coils are central components in an air conditioning system that contribute to cooling and efficiency; thus, their replacement can greatly impact how a system operates.

In contrast, repairs such as replacing a filter drier or a schrader valve core are typically classified as minor repairs. These repairs do not generally require the evacuation of the refrigerant from the system to the same extent and carry a lower risk to the environment concerning refrigerant emissions. The condenser fan motor replacement might also be seen as minor since it usually does not directly involve refrigerants or the sealed system's integrity as much as an evaporator coil replacement does. Therefore, the replacement of an evaporator coil is specifically highlighted under EPA regulations for its potential environmental impact during the repair process.