The utility model discloses a plastic width -lock type single -layer sealed packing case comprises a casin, including the host computer shell, the inside hollow structure that is of host computer shell, and the outside is the rectangle structure, the inside facing wall face of host computer shell sets up baffle and last baffle respectively, wall processing shaft hole around the host computer shell, be equipped with the rotation axis in the shaft hole, fixed median septum on the rotation axis, dock with last baffle and last baffle respectively at the median septum both ends, host computer shell inner wall, and it is equipped with the condenser directly over the baffle to be located, the beneficial effects of the utility model are that, a energy -efficient transducer air conditioning is provided, transducer air conditioning can measure according to rack inside variation in a thermal load automatically regulated cooler air -conditioner. Cooler air -conditioner volume increase when the equipment heating volume is big in the cabinet, the energy consumption risees, an equipment heating volume hour cooler air -conditioner volume reduces in the cabinet, and the energy consumption reduces.