1. The frost on the surface of the evaporator is too thick or too much dust. Because of the decrease of the heat exchange effect, the temperature of the room decreases slowly.
2. Due to the poor heat insulation or sealing performance of cold room, the cooling capacity loss is large. The thickness of thermal insulation layer of pipeline and warehouse insulation wall is insufficient, and the insulation effect is poor. It is mainly due to the improper selection of insulation thickness in the design of cold room or the poor quality of thermal insulation materials during construction.
3. The throttle valve is not adjusted properly. When the flow valve is opened too large, the refrigerant flow will be too large, the evaporation pressure and evaporation temperature will rise, and the temperature of the room will slow down. When the throttle valve is opened for an hour, the refrigerant flow is too small, the cooling capacity of the system will also be reduced, and the temperature drop rate of the room will also slow down.
4. Due to the long-term operation of the refrigeration compressor, the cylinder sleeve and piston ring and other parts are seriously worn, resulting in low efficiency of the refrigeration compressor.
5. There is lethal air or refrigerant oil in the evaporator.
6. The refrigeration dose is insufficient.