Abstract: A refrigerated display case system includes a display case that defines an inner volume; a closed-circuit refrigeration system; and a control system. The closed-circuit refrigeration system includes a compressor; a condenser assembly; and a cooling assembly that includes a cooling coil and an evaporator fan configured to circulate an airflow from the inner volume through the cooling coil to cool the airflow with a liquid phase of a hydrocarbon refrigerant supplied from the condensing unit. The evaporator fan is configured to circulate the cooled airflow to the inner volume to adjust or maintain a temperature of the inner volume. The control system is configured to perform operations including operating the condensing unit and the cooling assembly in a refrigeration cycle to cool the inner volume and a defrost cycle to defrost the cooling assembly; and operating the evaporator fan independent of the refrigeration cycle and the defrost cycle.