What to Do When the Compressor of a [Refrigerated and Frozen Display Cabinet] Unit Makes Abnormal Noises?

2025-04-05

In supermarkets, some refrigerated and frozen display cabinets have a split structure between the display cabinet body and the refrigeration unit. If abnormal noises are detected during the inspection of the refrigeration unit device, they are generally caused by the following factors:

Poor pipeline connection or fixation, which causes device vibration. Loose pipelines need to be re - fixed properly.
Loose or improperly installed foundation screws of the unit or installation screws of auxiliary equipment, which cause the device to vibrate and produce abnormal noises.
Insufficient refrigerant charge or blockage in the refrigeration system. It is necessary to increase the amount of refrigerant and check whether the liquid line filter is blocked.
Liquid compression occurs in the compressor. The compressor sucks in too much liquid refrigerant or lubricating oil, and the liquid stays in the crankcase. When starting, due to a sharp drop in pressure, abnormal noises are generated, which is commonly known as "liquid hammer".
It is necessary to measure the operating current of the compressor head, check the oil pressure, and observe the condition of the oil.
If it is found that the amount of oil is too much, an appropriate amount of oil should be drained from the oil drain hole of the compressor head. If the oil amount is normal, then check and adjust the operating conditions, check whether the opening degree of the expansion valve is too large. If the expansion valve is opened too wide, it will also cause liquid return. At this time, it is necessary to appropriately reduce the opening degree of the expansion valve.
If there is no liquid receiver set in the system, a liquid receiver needs to be installed to reduce the amount of refrigerant liquid entering the compressor. If the abnormal noise occurs during debugging, it is possible that the refrigerant charge is too large, resulting in continuous liquid return, and some refrigerant needs to be released.
Abnormal noises are caused by malfunctions of internal components of the compressor. For example, the motor rotor of the compressor rubs against the stator; the key of the flywheel or the motor rotor is loose; the piston connecting rod of the piston compressor is loose or worn; the bearing of the compressor is worn and the clearance of the bearing bush is too large; the clearance in the cylinder is too small; the clearance between the piston pin and the connecting rod bushing is too large; the piston pin lacks oil; foreign objects are sucked into the compressor; the oil - scraping ring is damaged; the discharge valve or suction valve of the compressor is broken or the spring is broken, etc. It is necessary to remove and disassemble the compressor for inspection one by one.