Refrigerator Compressor Making a Knocking Noise [How to Fix]

This article discusses the problem of a refrigerator compressor making a knocking noise. Learn how to fix it quickly.

Refrigerator Compressor Making a Knocking Noise

Refrigerator Compressor Making a Knocking Noise – Solved

First, ensure the noise is coming from the compressor area. Then, check the condenser fan before you check the compressor. If it is covered with dirt, it will work harder than usual to spread air. As a result, you hear a knocking noise. Since it is so close to the compressor, you may assume the noise is coming from the compressor.

Therefore, clean the blades and make sure there is no other form of obstruction keeping them from spinning. Check the area around the fan and compressor. If you can, clean the area as well.

But if the blades spin well and there is no obstruction, check the fan’s motor. It may be creating noise due to worn motor bearings. Stiffness from the blades when you try to turn them by hand indicates worn bearings. That is if the shaft is in good working condition.

Using a multimeter, run a continuity test on the motor. The test should whether or not the motor is still receiving power. If you find no continuity, it means the motor has failed and needs a replacement.

However, if all parts of the condenser fan are in good working condition, check the compressor. It may be it is not balanced, or there is internal damage. You may need to find a professional to check the compressor so you don’t misdiagnose it.

Important Note

When refrigerant is circulating, starting from the compressor, it tends to make a noise that sounds like knocking. That may be the source of the noise; verify it before touching the compressor.

Also, the condenser coils tend to make a knocking noise if they are dirty. You can verify if they are the origin if the refrigerator stops cooling as it should. It means the coils are not dissipating heat, and it is causing a rise in internal temperatures.

Giving the coils a thorough cleaning should fix it. A soft brush, a vacuum cleaner, or a condenser cleaning brush should do the job. But ensure you vacuum the area around the coils to remove every dirt and debris.

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What Causes a Refrigerator to Make a Knocking Noise?

The following are possible reasons for a knocking noise from a refrigerator:

1. Contact with Surfaces

During regular operation, a refrigerator may move ever so slightly. When it cycles off and on, it may hit the surrounding surfaces or objects close to it. In such a case, the refrigerator may create noise that sounds like knocking, depending on what it hits.

Move the refrigerator away from the surrounding surfaces to create some space between them. That way, the noise stops if it originated from there.

2. Dusty Condenser Coils

Dus and debris on the coils reduce their efficiency in dissipating heat. The heat causes noise from the coils, along with reduced cooling. If you hear knocking noise and the refrigerator does not cool, the condenser coils need cleaning.

Locate the coils using the user manual for the refrigerator. When you do, clean them using a condenser coil cleaning brush, a vacuum cleaner, or any soft brush. Make sure you clean them thoroughly and vacuum the floor around them to eliminate the possibility of dirt adhering to the coils again.

3. Dirty Condenser Fan

If the fan is choked with debris, it reduces the flow of air and creates a knocking, clicking, or whistling noise. When cleaning the coils, therefore, clean the condenser fan and the compressor to improve performance. A soft brush will do the job better than a condenser cleaning brush or a vacuum cleaner. Remember to disconnect the refrigerator from electric power before cleaning the components.

4. Compressor Operation

When the compressor starts or stops, you may hear a knocking noise. This is especially true if your refrigerator is an older model. A compressor in a newer model refrigerator may not generate the noise, but it helps to verify with the help of a professional. The compressor may simply need to be fixed or cleaned.

Quick Note

Always unplug the refrigerator from the wall outlet before cleaning the coils and fan. The same applies if you want to check the compressor.

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