What is true concerning frost build-up on the evaporator coils of a multi-box direct expansion refrigeration system?

Correct Answer: Option A — the frost can be removed by passing hot gas through the coils or energizing defrost heaters with the evaporator fan shut down

Defrosting evaporator coils requires either hot gas injection or electric heaters. The evaporator fan must be shut down during this cycle to prevent heat circulation into the refrigerated space and to keep melted frost from refreezing.