How do evaporators in medium-temperature refrigeration cases normally defrost?

How do evaporators in medium-temperature refrigeration cases normally defrost?

• A. The case air circulates over the coil while the compressor is off.
• B. The evaporator fan runs continuously to melt frost.
• C. Defrost is achieved by reversing the cycle.
• D. Defrost is accomplished with hot gas only.

Answer: (A)

Defrosting the evaporator in medium-temperature cases is normally done by letting the refrigeration cycle go into an off-cycle. When the compressor stops, cooling ceases and the coil warms up from the surrounding air. The case air keeps circulating across the coil, helping melt the frost, which then drips away. This approach uses no extra defrost heater or cycle changes and is simple to implement with standard controls, making it a practical default for many display and reach-in cases. Other methods, like electric defrost heaters, hot-gas defrost, or reversing the cycle, exist but are used in specific designs or situations rather than as the typical default.

Defrosting the evaporator in medium-temperature cases is normally done by letting the refrigeration cycle go into an off-cycle. When the compressor stops, cooling ceases and the coil warms up from the surrounding air. The case air keeps circulating across the coil, helping melt the frost, which then drips away. This approach uses no extra defrost heater or cycle changes and is simple to implement with standard controls, making it a practical default for many display and reach-in cases. Other methods, like electric defrost heaters, hot-gas defrost, or reversing the cycle, exist but are used in specific designs or situations rather than as the typical default.