A buzzing sound from a refrigerator can either signal a major problem or it can just be a nuisance. In many cases a buzzing sound is a common occurrence, and if it has been happening for a long time and there hasn't been a cooling problem, the chances are that it is normal. However, there are some buzzing noises that can be fixed, or at the very least, understood.
Buzzing on The Outside
Buzzing on the outside of the unit can come from many sources. Panels can be loose and vibrate or buzz when the unit is running. Things stacked or placed on the top can buzz, and magnets holding things on the side can buzz when the refrigerator is running. You can press on the sides of the fridge to see if the buzzing stops, or remove everything off the top and the sides to see if that eliminates buzzing.
Buzzing Near the Bottom
Buzzing near the bottom can be caused by an improperly balanced fridge. When the fridge runs, one or the other of the legs may just slightly be touching the floor, so that when the fridge runs, the leg vibrates or "buzzes" against the floor. You can determine if balance is the key by slightly tipping the fridge to remove all the weight from one side and then the other. If the buzzing stops, the legs need to be adjusted.
Self-defrost models and refrigerators with ice makers will buzz during their respective cycles. When water valves open to refill the ice maker, the unit will buzz. When water drips down onto the heated coils on a self defrost model, there will also be a buzzing sound. However, this type of buzzing will only last as long as the cycle lasts and will be intermittent and not constant.
Buzzing From Behind
In many cases, the compressor will begin to buzz as it becomes older and worn out. It may begin buzzing and last for years, or it may begin buzzing and break down within days. If you pull the fridge out from the wall and hear a buzzing noise coming from the lower rear area, the chances are it is the compressor. In this instance, you may want to call a professional and have it checked out.
The Drip Pan
The drip pan is located directly beneath the refrigerator. It is usually mounted on foam rubber so that it does not vibrate when the fridge is running. However, many times the drip pan can shift over to the side and slightly touch a cooling line or a radiator fin. When that occurs during the time when the fridge is running, it will vibrate so fast that it will buzz. You will have to get down on your hands and knees and listen carefully beneath the fridge. If you hear a buzzing noise, it is the drip pan. Simply move the pan back into place and the buzzing will stop.