Abstract: In a self-contained plug-in display cabinet system (100), the evaporation temperature of the evaporator (25) is between ?4° C. and 2° C., and with the adaption of constant pre-cooling means (22), the high-temperature and high-pressure refrigerant gas discharged by the compressor (21) is pre-cooled allowing use of a low system pressure ratio and, thus, a high temperature compressor (21). Furthermore, there may be no need for the evaporator to be defrosted, which overcomes the drawbacks of the currently available display cabinet systems that the refrigeration cycles have to be interrupted for defrosting the evaporator, thereby having further energy saving and being advantageous in keeping the temperature of the food stable.