DIAGNOSIS That's the variable-speed compressor (sometimes called a digital inverter compressor) ramping up or down. It's normal operation for this model, but excessive noise can point to a failing component.
FIX First, check if the noise is actually the compressor and not something vibrating.
1. Unplug the fridge for 2 minutes, then plug it back in. This resets the compressor control board and can quiet a noisy cycle.
2. Pull the fridge out and check the back panel. Ensure the condenser fan (at the bottom back) isn't hitting a wire or debris.
3. Tighten the compressor mounting bolts if they're accessible. A loose compressor amplifies the buzz.
IF THAT DIDN'T WORK If the buzz is a loud, constant rattle or grind, the compressor mounts or the compressor itself may be failing. This model has a known issue where the compressor can fail prematurely, often with a distinct knocking sound. That requires a technician.
HEADS UP Don't ignore a sudden, drastic increase in noise level combined with poor cooling. It's the main symptom of a failing compressor, and the repair is major and often covered under an extended service campaign for certain serial numbers.