Frosting at the return port of the compressor in a refrigerated compartment in Chongqing indicates that the temperature of the compressor's return gas is too low. What can cause the temperature of the compressor's return gas to be too low? If the return temperature of the refrigerated compartment compressor is low, it generally shows both low return pressure and high refrigerant volume of the same volume. The root cause of this situation is that the refrigerant flowing through the evaporator cannot fully absorb the heat required to expand to the predetermined pressure and temperature value, resulting in low temperature, pressure, and volume values of the return gas. This situation has two problems:

1. The evaporator of the refrigerated container is working normally for heat absorption, but the throttle valve has an excessive supply of refrigerant, which means that the refrigerant flow rate is too high. We usually understand it as excessive fluorine, which also causes low pressure.

2. The liquid refrigerant supply of the refrigerated container throttle valve is normal, but the evaporator cannot absorb heat and supply refrigerant expansion normally.

From this analysis, there is no possibility of compressor return air frosting due to insufficient fluorine. In fact, it is also possible that insufficient fluorine may cause frosting at the low-pressure port

3. Due to the extremely low flow rate of refrigerant, refrigerated containers will cause the refrigerant to flow out of the expandable space behind the throttle valve and begin to expand. We often see frost on the separation head behind the expansion valve due to lack of fluorine or insufficient flow rate of the expansion valve.

Insufficient refrigerant expansion will not utilize the entire evaporator area, but will only result in low temperatures in certain areas of the evaporator. Due to the low amount of refrigerant, some areas will rapidly expand, causing local temperatures to be too low and resulting in frosting of the evaporator.

Due to the formation of a thermal insulation layer on the surface of the evaporator and the low heat transfer in this area, the refrigerant expands and transfers to other areas, gradually leading to frost or ice formation throughout the evaporator. The entire evaporator forms a thermal insulation layer, and the expansion spreads to compression

4. Due to the insufficient amount of refrigerant in refrigerated containers, the low evaporation pressure of the evaporator leads to low evaporation temperature, which gradually causes condensation on the evaporator to form a thermal insulation layer and transfers the expansion point to the compressor return air, resulting in frost formation on the compressor return air.