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Why is My Refrigerator Making a Knocking Noise

Why is My Refrigerator Making a Knocking Noise

A refrigerator is such a helpful and convenient appliance to have in your home. That’s why it can be very frustrating when it starts developing issues. Usually, a refrigerator’s compressor will make some humming or buzzing noise when running on a day-to-day basis, which shouldn’t alarm you. One of the most commonly reported issues with refrigerators is a knocking noise that can disturb your sleep at night.

There are a couple of culprits that may be responsible for a knowing noise. The primary cause for a knocking sound could be a problem in the compressor or condensing mechanisms. To properly diagnose the issue, you need to find out where the knowing sound is coming from. This article explains the probable causes for a knocking sound and how to fix the issue.

Why is my refrigerator making a knocking noise?

Here are the reasons that can cause a knocking noise in your refrigerator and how to fix those issues.


Typically, a compressor will make make a knocking sound when it starts and stops at certain hours of the day. This sound is usually low, doesn’t stay too long, and mainly in the older model refrigerators and should not worry you. But if the knocking sound is new, there could be a problem with your compressor, or the problem could be unrelated to the compressor.

An unbalanced motor inside the compressor can create a knocking sound in your refrigerator which a technician can quickly fix. If your compressor is faulty, you will have to get a technician to fix it or getting a replacement.

Condenser coils

Condenser coils are responsible for the cooling and condensing of the refrigerant. When the coils are clogging with dust, dirt, and other household debris, they can’t efficiently release the heat, and this may cause a knocking noise. If you suspect that you have dirty coils, turn off your refrigerator, access the condenser coils at the back of your refrigerator, and clean the condenser coils with a soft brush or shop-vac.

Condenser fan

The condenser fan cools down the compressor and condenser as they produce heat when they are running. When the fan jams with dirt, it starts to run slower, and there is less airflow which creates a clunk sound when turning. To clean the condenser fan, cut off power from the refrigerator, open the cover at the back, and use a brush and vacuum to clean the fan blades.

Ice maker

Refrigerators that come with ice makers and water dispensers can also be the source of the knocking sound. The ice maker will make a banging noise when filling with water from the water lines due to high pressure. However, the ice maker makes a loud clunk noise when there is a blockage in the water pump. You will have to turn off the refrigerator, locate the blockage and clean it out. Blockage can come in the form of dirt, hard water mineral deposits, or frozen water.  

Vibrations from wall contact

Luckily, sometimes the knocking sound may not be a problem with the refrigerator. Instead, the normal vibration from the fridge could be causing the unit to bang on the wall. You should move your refrigerator about 2-4 inches from the wall.

What does a bad fridge compressor sound like?

When the fridge is running correctly, it will make a low humming sound and the periodic knocking sound of the compressor starting and stopping. But a faulty fridge will make different noises that are loud and consistent. Some of these noises include:

Clicking sound

A consistent clicking sound from the refrigerator could mean that the ice maker is on, but the water supply is off. It could also indicate a broken connection in your refrigerator.

Knocking sound

The main reason your fridge keeps making a banging noise is from a problem in the circulation cycle, usually from a clogged condenser coil and fan or a loose part in the compressor.

Chirping sound

If you hear a squealing or chirping noise that sounds like a bird coming from the fridge, there could be a malfunctioning evaporator fan. The evaporator fan draws air through the evaporator coils to remove the heat from the air. This airflow is crucial for the unit to work correctly.

What happens when the compressor goes out in a refrigerator?

The compressor acts as the heart of the refrigerator’s cooling system. The compressor is a motor that controls the circulation of the refrigerant. It increases pressure on the refrigerant and heats it, and sends it to the evaporator. It then carries the vapor to maintain low pressure and low temperatures and then sends it to the condenser.

So if the compressor goes out, the refrigerator is rendered useless for preserving perishables as it loses the cooling effectiveness. The worst case is the entire refrigerator will shut down.

How much does it cost to replace a compressor in a refrigerator?

Depending on type and size, a new compressor will cost about $50 to $300, with labor costs ranging between $100 to $200. Replacement compressors come either new or reconditioned, and new compressors are pricier. We advise getting a new one, but you can get a reconditioned one if you are working with a strict budget.

Is it worth replacing the compressor on a refrigerator?

The compressor plays a very vital part in the overall function of the refrigerator. But when it fails, you may want to consider a few factors before choosing to replace the fridge. Here are those factors;

Age of the refrigerator

All refrigerators have a lifespan, and some do have longer lifespans than others, after which they start to become ineffective in cooling. How long your refrigerator depends on the maintenance and brand. Understanding the lifespan of your refrigerator will help you know if you should invest in a new compressor. Most appliances have a lifespan of about 10 to 15 years. So do not recommend replacing a compressor with two or three years left on your unit.


Replacing a compressor can cost you between $200 to $500, and high-quality brands cost much more. Sometimes a failing compressor is usually due to a different fridge problem, such as; evaporation and compression issues or a motor problem. You will need to address the root problem after a compressor replacement which subsequently costs much more.

Also, some people report experiencing more issues with their refrigerator after a compressor replacement. Some compressors cost half as much as and if your unit has been in service for about 15 years, replacing the entire refrigerator may be much more cost-effective than replacing the compressor. Most refrigerators have a one or two-year warranty and a compressor replacement by the manufacturer at zero cost.

Type of refrigerant

If you have an older model fridge that uses certain refrigerant types such as R12, R22, or R502, it’s better to buy a new refrigerator. These types of refrigerants are not in the market today.   Most modern fridges use the R134a and R1234yf refrigerants, which are not compatible with older refrigerant systems.

Check this too: How Many Amperes Does a Refrigerator Use

Condition of the refrigerator

Before buying a compressor, you should examine the general condition of your fridge. Check for worn-out door hinges, loose seals, damaged coils, and fan blades. If these parts are bad, buying a new fridge would be more advisable.


A knocking noise from your refrigerant is not always a bad sign. It is best if you check if it persists. If it does, you should consider getting a compressor replacement or simply buying a new refrigerator.