Refrigerator making a loud buzzing or humming noise — San Francisco, California

A persistent loud buzzing, humming, or grinding noise from a refrigerator usually points to one of several mechanical issues. The most common culprit is a failing evaporator fan motor (located behind the freezer panel)—when its bearings wear out, it produces a loud buzzing that gets worse when you open the freezer door. A malfunctioning condenser fan motor (at the bottom rear) creates a similar drone and can cause the compressor to overheat. Ice buildup around the evaporator coils from a defrost-cycle failure can also cause the fan blades to scrape against ice. Less commonly, the compressor itself may be failing, producing a low grinding hum. An appliance repair technician can diagnose the source, replace the affected fan motor ($100–$250 including labor), or clear the ice buildup and fix the defrost system to restore quiet operation.