The location and environment of the air evaporator inside the cold storage will affect its operation. Generally, the fan near the cold storage door is prone to condensation and frost. Because its environment is at the doorway, hot air flows outside the door when the door is opened, and when it encounters the fan, condensation and frost, or even ice, will occur. Although the fan can automatically heat and defrost at regular intervals, if the door is opened too frequently, the opening time is too long, and the time and quantity of hot air entering is long, the defrosting effect of the fan is not good. Because the defrosting time of the fan cannot be too long, otherwise the refrigeration time will be relatively shortened, the refrigeration effect will not be good, and the storage temperature cannot be guaranteed. In some cold storages, due to too many doors, the opening frequency is too high, the time is too long, there is no insulation measures at the door, and there is no partition wall inside the door, so that the cold and hot air flows between the inside and outside are directly exchanged, and the air cooler near the door will inevitably encounter serious problems. Frost problem.