Cold storage machine unit is composed of compressor, condenser, evaporator and other components. The compressor is the core of the unit, and its purpose is to compress refrigerant to form high temperature and high pressure gas, which is sent to the condenser, cooled and condensed into liquid, and then sent to the evaporator through the throttling device. In the evaporator, the liquid refrigerant absorbs heat from the cold storage room and evaporates into gas. The gas is sent to the compressor again by the circulation of the refrigerant, and the cold medium of the refrigeration cycle is formed. 冷库机组由压缩机、冷凝器、蒸发器等组件组成。压缩机是该机组的核心，其目的是将制冷剂压缩成高温高压气体，送入冷凝器冷却凝结成液体，再经节流装置送入蒸发器。在蒸发器中，液体制冷剂吸取冷库室的热量蒸发成气体，气体又经制冷循环而送回压缩机，形成制冷循环的冷媒。

制冷机组常见故障排除：电动机不能启动，主要由于供电电路、控制电路及电动机本身出了故障。 运行中突然停车，主要由吸气压力过低、排气压力过高、润滑油压力太低、电动机超载等引起。 制冷量不足，主要由蒸发器结霜太厚、冷冻室的密封及绝热性能差、膨胀阀流量太大、系统内有空气、制冷剂充注过多、过滤器不畅通、膨胀阀堵塞、制冷剂不足、蒸发器里有油等原因引起。 不制冷；主要是系统中制冷剂不能循环流动所致。 压缩机本身的故障。制冷系统发生故障后，必须分段检查，查明原因，采取合适的措施予于排除。

制冷机组的保养 1、换油：机组每年必须换冷冻油一次，或视实际情况或油品分析结论决定需否提前换油。 2、换油过滤器：当油压下降了30%或机组运行半年后更换油过滤器。同时检查过滤器中是否存在金属屑，以确认机组内部的磨损状况。 3、紧固滑阀：检查并紧固滑阀的管路联结。