Refrigerator Making Knocking Noise? Here’s Why

Paradise Appliance
December 2, 2021
Refrigerator Repair

Refrigerators make all sorts of different noises while operating. Most of the time, this isn’t something to be worried about unless the noise is loud. One of the noises that indicates a more serious problem is a loud knocking noise coming from your fridge. 

If you can hear a loud knocking noise, you will need to inspect the evaporator fan, the condenser fan, and the compressor, as these are the most likely causes of the problem if they have become faulty.

Before you check those components, make sure that the problem is not being caused by anything in your fridge knocking into the wall of the fridge when the compressor is working. You should also make sure that your fridge is sitting level on the kitchen floor.

If those two simple fixes don’t work, you’ll need to check the internal components.

Faulty evaporator fan

The purpose of the evaporator fan in your refrigerator is to distribute cold air around your fridge. When it becomes faulty or blocked from rotating around properly, your fridge will not be able to cool down, and the fan might make a knocking sound.

The easiest way to check if the evaporator fan is causing the problem is to see if your fridge is warm and isn’t cooling properly. If this is the case, this means the evaporator fan isn’t working. 

To check the evaporator fan:

  1. Turn your fridge off and let it defrost. Once defrosted, plug it back in, and see if the problem has been solved.
  2. If the noise is still happening, locate the evaporator fan and remove the cover from it.
  3. Inspect the fan to see if it is dirty, and if so, give it a good clean. You can then try to rotate the fan around 360 degrees to check if it is obstructed in any way. If it is obstructed, remove the foreign object causing the obstruction, and then put the cover back on and test if the problem has been solved. If you can still hear a knocking sound, you’ll need to check the condenser fan (see the next step below).
  4. If the fan isn’t being obstructed, you’ll need to disconnect the fan motor and then test it with a multimeter. If you don’t have a multimeter or you don’t know how to use one, you’ll need to call a technician to come and inspect the motor.
  5. If the test shows the motor has continuity, this means it is working correctly, and you can reconnect the motor and move on to the next component. If, however, the motor has no continuity, it will need to be replaced.
  6. Once the new motor has been installed in your fridge, you should test if the knocking noise has stopped. If not, you will have to check the condenser fan.

Faulty condenser fan

If the knocking noise is coming from the back of your fridge, it is most likely being caused by a faulty condenser fan. The purpose of the condenser fan is to help cool the condenser coils. When it doesn’t work, the coils will overheat, and your fridge won’t cool. It can also cause a knocking noise because the fan can come into contact with ice or hit another object at the back of the fridge.

To test the condenser fan, there are a few steps you need to take:

  1. Turn the power to the fridge off, and pull the fridge out from the wall so you can gain access to the condenser fan.
  2. Locate the fan (you will probably have to take the back panel off).
  3. Check the fan for any signs of damage and if it is frozen over or dirty.
  4. If the fan is dirty or frozen over, you will need to let it defrost and/or give it a good clean before plugging it back in again.
  5. If the fan isn’t damaged in any obvious way, attempt to turn it around 360 degrees a couple of times to check if it is obstructed in any way. If it goes around freely and it is clean, you can move on to checking the next component.
  6. If the fan is damaged, try to remove what is obstructing it, and if that isn’t possible, it will need to be replaced.
  7. If you replace the fan, you will need to check if the knocking sound has stopped once it is installed and the fridge is turned back on. If not, check the compressor.

Faulty compressor

The final component to check is the compressor. The compressor is the main component in your fridge that helps to make it operate correctly, as it distributes refrigerant around your fridge. 

If your compressor becomes faulty, you may hear a knocking sound coming from it. Replacing a compressor is very expensive, so you’re probably better off buying a new fridge. They are also difficult to repair, and any repairs should only be carried out by a qualified technician.

However, before calling a technician, turn your fridge off, locate the compressor, and check it over for any signs of loose parts. If you find anything loose, try to tighten it up if possible, and then check if the knocking sound stops. If you can’t find any loose parts, you will need to call a technician or purchase a new fridge.


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