Commercial Refrigeration Certification Practice Test

Defrosting a low temperature evaporator is most effectively achieved using electric heaters. This method involves applying heat directly to the evaporator coil, which helps to melt any accumulated frost or ice that may have formed due to moisture in the air condensing and freezing on the coil's surface. Electric heaters provide a controlled and efficient means of delivering heat, ensuring that the defrost process is effective without damaging the components of the refrigeration system.

While stopping the evaporator fan motor can reduce airflow and temporarily limit frost buildup, it does not actively remove existing frost or ice. Reversing the compressor rotation is not a standard method for defrosting; this action would not be effective in melting frost. Installing a modulating valve could potentially regulate refrigerant flow, but it won't directly contribute to the defrosting process as electric heaters do. Therefore, using electric heaters is the most reliable and commonly implemented technique to accomplish the defrosting of a low temperature evaporator.