Although truck reefer unit has its own automatic hot gas defrosting function, if it is used improperly, it will still cause the freezer unit to defrost. The frosting of the compressor of the reefer unit will be a "fatal blow" to the compressor, and will reduce the effect of refrigeration. How to avoid the frosting of the truck reefer?
1. The refrigerant charge is large or small. Excessive amount will increase the condensing pressure and increase the liquid entering the evaporator. The liquid cannot be completely vaporized, and the compressor sucks in liquid with gas mixed with refrigerant. As a result, the temperature of the return air duct drops, but the evaporator temperature remains unchanged due to the increase in pressure, and the degree of superheat decreases. Too little refrigerant will condense from the evaporator to the compressor. So refrigerant charging is definitely a technical job!
2. Expansion valve. The opening of the expansion valve is too large. Due to the loose binding of the temperature sensing element, the small release area from the return pipe, or the temperature sensing element is not wrapped with insulating material, or the wrapping position is wrong, etc., the temperature measured by the temperature sensing element is not accurate and expands The valve opening degree increases, resulting in excessive liquid supply.
3. External reasons cause the refrigerant to evaporate in the evaporator inadequately, or even not to evaporate. At this time, it will cause severe frosting or wet compression. (For example, insufficient return air and low exhaust temperature)
