There are some noises that are so common that you barely even register their existence. You can certainly hear your refrigerator as it cycles, but this is generally little more than background noise. This duty cycle is when the condenser fan motor runs (pushing cold air into the interior of the refrigerator), followed by a quiet period. The cycle regularly repeats (as it should), and the frequency of the cycle will vary depending on the manufacturer and model of your refrigerator. A change to the sound of your refrigerator's duty cycle can be an indicator that the device is not operating as efficiently as it should.
You might notice that the noise of the duty cycle is louder than it used to be, or the noise might have more intensity—somewhat like when a car's muffler is struggling. Your refrigerator might also be moving through its duty cycle at a greater speed, meaning it will sound like the condenser fan motor is running more often than it should. So what can cause these changes to your refrigerator's duty cycle? And what can you do to fix the issue?
When the sound of the duty cycle takes on a noticeable intensity, the problem is hopefully rather easy to rectify. The operation of the condenser fan motor causes your refrigerator to vibrate ever so slightly. Open the refrigerator to check whether anything is touching the sides or door. If a glass or metal container is positioned too close to the sides or door of the refrigerator, you might in fact be hearing this object vibrate as opposed to it being caused by the operation of the refrigerator itself. Move the objects further into the interior of the refrigerator and this should reduce the intensity of the noise.
Louder, More Frequent Noise
If there are no likely objects that might be causing this change to the sound of your refrigerator's duty cycle, the issue might in fact be with the refrigerator itself. The sound might be louder and more frequent if the refrigerator's condenser coils are struggling to maintain the device's interior temperature. Refrigerator vapour is pushed through the device's compressor and into its condenser coils, which are located on the rear of the device and are generally external. The room temperature in your kitchen allows these coils to cool the vapour as it moves through them before it's pushed through an expansion device and back into the refrigerator's interior. When these coils are dirty, they cannot adequately cool the refrigerator vapour.
It can be as easy as safely moving the fridge away from the wall so that you can remove any accumulated dust from these coils. Ensure that the refrigerator is switched off and simply dust the coils with a soft dry cloth. You can also use the brush attachment from your vacuum cleaner. Make sure that only the bristles of the attachment touch the coils as the hard plastic of the attachment itself might cause damage.
The Condenser Fan Motor
If the sound of the refrigerator duty cycle remains excessively loud or frequent after ensuring that it's not an object inside your refrigerator or the cleanliness of the condenser coils, then the issue might be with the condenser fan motor. You should call a professional to have this inspected and repaired or replaced as needed. A malfunctioning condenser fan motor can be very loud indeed, and it can result in your refrigerator not maintaining the desired temperature. Check to see if your refrigerator is still under warranty as the manufacturer might have a preferred repairer.
So while the usual operation of your refrigerator might be little more than background noise, it's important to listen for any changes to this noise.