Normal Fan and Compressor Noises
A refrigerator's compressor works as a pump to move refrigerant through the system and keep the inside of the refrigerator cool. The compressor fan draws air over the compressor and keeps the compressor and the refrigerant cool.
The compressor and fan respond automatically to changes in temperature in the system, switching on when they're needed, and you're likely to hear them running much of the time. The fan may increase its speed, and thus get louder, after you open the refrigerator door.
The compressor may also make a clicking sound as it switches back on after a power outage.
The circulation of refrigerant through the system may cause a gurgling or bubbling sound.
If you're aware of the noises your refrigerator makes when it's operating normally, you'll be better able to identify abnormal sounds that indicate a problem. As a compressor begins to fail, the noise it makes may change; it may get louder or it may begin to rumble. If the change happens suddenly, or if it gets steadily worse over a short period of time, the compressor may be about to fail, and it should be checked by a technician.
Condenser Fan Problems
A failing condenser fan is a more common cause of abnormal noise near the compressor. If you hear a rumbling or rattling sound when the compressor is running, check for an obstruction of the fan blade by unplugging the refrigerator and removing the rear panel. Clean the fan blades and remove any obstructions. If that doesn't solve the problem, or if the fan motor is making grinding or whining noises, the fan bearings may be failing and the fan motor may need to be replaced by a technician.
Normal Control System Noises
Refrigerators are equipped with thermostats that control the cooling system, and you may hear a clicking sound when the thermostat switch is triggered to turn the system on or off.
Automatic defrosting systems in frost-free freezers are equipped with timers to control defrost cycles, and the timers may also make a clicking sound when they switch on or off.
Normal Defroster Noises
An automatic defroster in a freezer works by periodically activating a heater to melt ice that builds up on the freezers evaporator coils. When condensation drips onto the heating element, you may hear a sizzling or crackling sound, and you may hear a cracking sound as the evaporator coils cool after a defrost cycle.
You may also hear the sound of condensation dripping into the refrigerator's drain pan after a defrost cycle.
Evaporator Fan Problems
A squealing, grinding or rumbling noise coming from inside the freezer may signal an obstructed or failing evaporator fan. These noises will sound louder when you open the freezer door.
To check the evaporator fan, unplug the refrigerator and remove the panel on the inside of the freezer at the back. Clean the fan blade and remove any obstructions. As with the condenser fan, a noise that continues after you clean the fan may be a sign of a failing fan motor that requires replacement.
Water Dispenser and Ice Maker Noises
You'll hear the sound of water being pumped into the ice maker when it refills at the beginning of an ice-making cycle, and finished ice cubes dropping into the ice storage bin make a loud thunk.
The water pump will also make a humming noise when the water dispenser is in use, and water draining from the dispenser can cause a gurgling sound in the door when the door is opened.
Unusual ratcheting sounds during ice maker operation may be caused ice buildup inside the ice maker. Remove the ice bucket to check for buildup, and remove any ice you find. If any parts of the ice maker are cracked or broken, call a technician.
Vibrations and Squeaks
Vibration sounds may be caused by objects on top of the refrigerator, objects inside rattling against shelves, or the refrigerator itself vibrating against walls or cabinets. In these cases, the solution is as simple as moving the vibrating objects and ensuring that the refrigerator is not in contact with walls or cabinets.
Squeaking door hinges are also an easy fix -- lubricating the hinges with petroleum jelly, paraffin or mineral oil will usually quiet the noise.