What should I do if the refrigerator air return pipe freezes?

The evaporator cannot absorb heat normally, or the cold generated by the evaporator cannot be taken away. The appearance is that the liquid return temperature and pressure are normal or slightly lower, and frost gradually forms from the liquid return port of the compressor to the evaporator. After a long time, all sections from the compressor return port to the evaporator and from the throttle valve to the evaporator were frozen, and finally low pressure appeared.

Less refrigerant

Due to the small amount of refrigerant, the evaporation pressure and temperature of the evaporator are low, which will gradually lead to the condensation of the evaporator to form a heat insulation layer and transfer the expansion point to the compressor return air, resulting in frosting of the compressor return air. If the fluorine content is normal or excessive, if the high pressure is low due to excessive condensation and heat transfer, the refrigerant at the front end of the throttle valve will show low pressure and high quality under the same volume.

Expansion valve pressure is low

When the initial throttle valve is opened, the quality of refrigerant liquid flowing through the throttle valve will be much higher than normal, and the heat absorbed from the evaporator will be too much. If the corresponding heat cannot be completely absorbed from the evaporator, the temperature of the compressor oil return pipe will be very low. At the same time, due to the low pressure at the front end of the throttle, the pressure at the rear end of the throttle will also be low. If the expansion valve is used in the air return pipe system of the refrigerator, the opening will not be adjusted too much compared with the normal state, so the low pressure will be maintained until the return air of the compressor is frosted, which seems to be a fluorine shortage phenomenon, and the frosting is caused by the low temperature of the air return pipe.