Most refrigerators make a fair amount of noise when running. They create a variety of sounds, such as clicking, dripping, whirring, whooshing and even humming at different points of normal operation. If the refrigerator seems to hum all the time or the humming sound is very loud, however, some investigation is required. In most circumstances, though, it is not dangerous for a refrigerator to be humming.
Condenser Coils
Humming sounds often come from the condenser coils in the rear of the refrigerator and occur when the coils get dirty or dusty. The dirt on the coil causes noisy airflow. Unplug the refrigerator and move the refrigerator back from the wall, then use a soft brush to clean the condenser coils thoroughly. Sometimes there is a cover over the condenser coils that needs to be removed to access the coils. When the condenser coils are clean, move around to the front of the refrigerator and take off the toe grille. Finish cleaning the coils from the front of the appliance.
Condenser Fan
Located above the condenser coils in the back of the refrigerator is a small fan. Like the condenser coils, the condenser fan accumulates dirt and debris. This dirt restricts airflow and causes a humming sound. Check the fan every time you inspect the condenser coils, and use the same brush to clean the fan when you clean the coils.
Fan Motor
In addition to the condenser fan, refrigerators also have a fan in the freezer that aids with evaporation and prevents ice buildup. The freezer fan may get noisy over time, causing a loud humming sound. Check the freezer fan by opening the freezer door and pressing the fan or light switch. If the humming sound gets louder, the fan motor likely needs to be replaced. Contact the refrigerator manufacturer or other authorized service professional for assistance.
Leveling
The refrigerator may operate more loudly if the legs on the refrigerator are not level, causing the refrigerator to vibrate and hum. Locate the adjusting screws on the bottom front of the refrigerator, which are sometimes located behind the toe grille. Use an adjustable wrench to turn the screws clockwise to lift up the refrigerator or counterclockwise to lower it. Use a level to determine when the refrigerator is positioned correctly. You can also test how level the appliance is by opening the doors halfway; when the doors close easily, the refrigerator is level.