Why Is My Refrigerator Making a Knocking Noise?

When your refrigerator starts making strange knocking noises it means something is wrong with one or multiple components within the fridge that will need to be diagnosed and fixed. Most of the time the noise can be stopped by carrying out a simple repair like making sure your fridge is level or cleaning the condenser coils. However, in some cases, you will need to check internal components such as the evaporator fan, condenser fan, and compressor. To find the cause of the knocking noise simply start at the top of this article and work your way down. Hopefully, by the time you get to the end of the article, you will have found the cause of the problem and fixed it.

Your refrigerator might not be level

Sometimes, a knocking noise can be caused by your refrigerator not sitting level on the ground. When this happens, food and other items in your fridge might knock into the sides of the fridge while the compressor is operating. To ensure your fridge is sitting level, simply place a bubble level on top, and if it’s not level, adjust the legs until it is.

The condenser coils might be frosted

At the back of your fridge are a set of condenser coils that can sometimes become frosted over which causes a knocking sound to emit from your fridge. To rule this out as the cause of the knocking noise, you need to:

1. Pull your fridge out from the wall and switch the power off.
2. If the condenser coil unit has a cover, remove it.
3. Inspect the coils for any frost.
4. If frosted, leave your fridge off to let them defrost. If fine, move on to checking out the next possible cause.
5. Once your fridge and the coils are defrosted, turn your fridge back on and check if the noise has stopped. If not, move on to checking out the next possible cause.

The condenser fan might be faulty

The next component to inspect is the condenser fan. You can find the condenser fan at the back of your fridge close to the condenser coils. This fan helps to keep the coils cool and sometimes it can become frosted over or obstructed which can cause a knocking sound to emit from your fridge. When this happens your fridge might need to be left to defrost or the fan motor might even need to be replaced. Here’s how to check the condenser fan:

1. If you haven’t already, pull your fridge out from the wall so you can access the back of it. 
2. Locate the condenser fan and take the cover off.
3. Check the fan to ensure it isn’t frosted over. If it is, leave your fridge turned off and let it defrost before turning it back on again.
4. If the fan isn’t frosted over, manually rotate it to ensure nothing is obstructing it. If anything is stopping the fan from being able to rotate, remove it. If the fan isn’t being obstructed, you can put the cover back on it and then move on to check the next possible cause of the knocking noise. If the fan is unable to rotate and you’re unable to repair it, the fan will need to be replaced.
5. Once you’ve repaired or replaced the condenser fan, turn your fridge back on and check if the noise has stopped. If you can still hear the noise, move on to checking out the next possible cause.

The evaporator fan might be faulty

Your refrigerator unit also has an evaporator fan that is located in the freezer compartment. The purpose of this fan is to distribute cool air from the freezer to the fridge. When it becomes faulty or freezes over, a knocking noise might emit from your fridge. Here’s how to check the evaporator fan:

1. Turn the power off to your fridge.
2. Open the freezer door and locate the evaporator fan unit.
3. Take the cover off the fan.
4. Check the fan to ensure it isn’t frosted over. If it is, leave your refrigerator turned off and let it defrost before turning it back on again.
5. If the evaporator fan isn’t frosted over, manually rotate it to ensure there are no obstructions. If anything is stopping the fan from being able to rotate, remove it. If the fan isn’t being obstructed, you can put the cover back on and then move to check the next possible cause of the knocking noise. If the fan is unable to rotate and you’re unable to repair it, the fan will need to be replaced.
6. Once you’ve repaired or replaced the evaporator fan, turn your fridge back on and check if the noise has stopped. If you can still hear the noise, move on to checking out the next possible cause.

The compressor might be faulty

The final cause of a knocking noise to investigate is a faulty compressor. The compressor helps to produce and distribute refrigerant around your fridge. Over time, compressors can wear out and parts within them can stop working which can cause noises to emit from them. To determine if your compressor is faulty, the easiest way to do it is to pull your fridge out from the wall, locate the compressor, and then check if you can hear any noises coming from it. If so, this is a good indication that the compressor has an issue and will need to be repaired. Repairing compressors is a difficult task that requires the right tools and experience so we recommend you call a technician. However, keep in mind that repairing, and if necessary, replacing a compressor can be expensive so you might decide you’re better off purchasing a new fridge or, if the noise isn’t too loud, living with it.