Before starting the air evaporator, check whether the motor drive mechanism is in good condition, whether the blades and protective covers are intact, whether the blades are frictionless with the air cylinder and the shell, whether the rotation is loose, and whether the lubrication is in good condition. The cold air system with air ducts and outlet air gates should adjust the air volume and air pressure according to the indoor air circulation requirements and the cargo situation to make the air distribution uniform. Frost should be formed on the surface of the cooling pipe group of the air cooler in operation, but the frost should not be too thick, so as not to affect the heat transfer and air flow. Therefore, the frost should be timely washed during use. During normal operation, the surface of the evaporating coil of the air cooler should be evenly frosted. If it is found that the frosting is uneven, it means that the liquid supply is abnormal, and it should be adjusted, and the liquid supply valve should be opened appropriately to increase the liquid supply.