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

Evaporator frost acts as an unwanted thermal insulator, drastically reducing heat transfer efficiency. Removing frost requires shutting down the evaporator fans to prevent heat distribution through the space while energizing internal electric defrost heaters or applying hot gas.