The grinding noise in a refrigerator compressor during startup or shutdown can be caused by a few different factors:
High Pressure in the Compressor: When the refrigerator is turned off or on, the refrigerant pressure inside the compressor changes rapidly. If the pressure is too high during startup or shutdown, it can cause the compressor to make a grinding or rattling noise.
Worn Bearings: Over time, the bearings in the compressor may wear out or become damaged. Bearings help the compressor's moving parts rotate smoothly. When they are worn, the rotating parts may make contact with each other, resulting in a grinding noise.
Loose Components: Vibration during startup or shutdown can cause some components in the compressor or surrounding area to become loose. Loose parts may rattle or grind against each other, producing the noise.
Faulty Motor or Mounts: The compressor motor or its mounting mechanism could be faulty. If the motor is misaligned or damaged, it may produce unusual noises during operation.
Compressor Age and Wear: Older compressors might be more prone to making noises due to wear and tear over time.
It's worth noting that not all refrigerators will make grinding noises during startup or shutdown. If you notice a sudden change in the noise level or suspect a problem with your refrigerator's compressor, it's essential to have it checked by a qualified technician. A professional can diagnose the issue and perform any necessary repairs or replacements to keep your refrigerator functioning correctly and efficiently.