Appears after a long period of normal use. This kind of failure occurs regularly and is easier to judge. For example, the cooling difference can only be leaked and the compressor discharge performance is poor. It is not necessary to consider the amount of refrigerant added. If the noise is large, only the resonance of the compressor itself and the exposed refrigeration pipeline should be considered. Need to consider taking time out is not clean. The secondary failure refers to the occurrence after repair or repair by others. This type of failure is irregular and complicated. In addition to considering the performance of the device itself, the operation level of the repairer, the specification and quality of the replacement parts, etc. must also be considered. The four types of failures such as ice blockage, unclean evacuation, welding blockage, and excessive refrigerant filling are unique to the secondary failure machine. The characteristics of ice blocking: display cases frost and defrost periodically, because the system contains water and is not clean. Features: poor cooling or no cooling, display cases have   snoring and   sound during operation, and the condenser is locally overheated and local to normal temperature. Welding plugging characteristics: no cooling, the noise of starting up gradually increases after adding refrigerant. Characteristics of excessive refrigerant filling: poor cooling, frost on the return pipe.

(2) When the compressor is running and the sound of refrigerant flowing, there are metal sheet vibration noises when the compressor is running, and most of the valves in the compressor are broken, resulting in display cases The compressor does not discharge or the discharge is poor. The compressor is running normally at the moment of starting, and then the running noise gradually increases. It is a blockage of the refrigeration system, which is only seen in the secondary failure machine, and is generally a welding block. The welding block occurs mostly at the connection port of the capillary tube and the filter dryer. After a period of normal operation of the compressor, the sound of the compressor gradually becomes dull. The refrigeration system is dirty and clogged. This is only seen in a malfunctioning machine. It is mostly caused by metal chips or other dirt during welding to block the capillary tube. Open the freezer door when the compressor is running, and no sound of refrigerant flow is heard, indicating that there is no refrigerant or blockage in the refrigeration system.