1. Insufficient air volume supply, including blockage of air outlet and return air duct, blockage of the filter screen, blockage of fin gap, non-rotating fan or reduced speed, etc., resulting in insufficient heat exchange, reduced evaporation pressure, and reduced evaporation temperature;

2. The problem with the heat exchanger itself, the heat exchanger is often used, the heat transfer performance decreases, and the evaporation pressure decreases;

3. The external temperature is too low, and civil refrigeration generally will not be lower than 20°C. Refrigeration in a low-temperature environment will cause insufficient heat exchange and low evaporation pressure;

4. The expansion valve is blocked or the pulse motor system that controls the opening is damaged. In the long-term operation of the system, some sundries will be blocked at the expansion valve port to make it unable to work normally, reducing the flow of refrigerant, reducing the evaporation pressure, and abnormal opening control. It will also cause the flow to decrease and the pressure to decrease;

5. Pipe bending or debris blockage inside the evaporator causes secondary throttling, which reduces the pressure and temperature of the part after the secondary throttling;

6. The system is poorly matched. To be precise, the evaporator is small or the working condition of the compressor is too high. In this case, even if the performance of the evaporator is fully exerted, the suction pressure will be low and the evaporation temperature will drop due to the high working condition of the compressor. ;

7. Lack of refrigerant, low evaporation pressure, and low evaporation temperature;

8. The relative humidity in the storage is high, or the installation position of the evaporator is wrong, or the cold storage door is opened and closed frequently;

9. The defrosting is not clean. Due to the insufficient defrosting time and the unreasonable position of the defrosting reset probe, the evaporator starts to run when the defrosting is not clean. The local frost layer of the evaporator freezes and accumulates after several cycles.