The sudden appearance of extraneous sounds in kitchen appliances always causes concern for the owner. If the refrigerator started knocking, this cannot be ignored, since noise often indicates a mechanical malfunction or violation of operating conditions. Loud knocks can be both harmless and a harbinger of serious compressor failure.
The first thing to do is to determine the nature of the sound and its localization. The knock can be dull, ringing, rhythmic or chaotic. Engineering analysis acoustic signals help to quickly identify a node that requires intervention. In this article we will analyze in detail all possible causes and methods for eliminating them.
It is important not to panic, but to act consistently. Many problems can be solved by simply adjusting the legs or defrosting the chamber. However, if the source of the sound lies inside the unit, more in-depth diagnostics will be required. Let's look at the main scenarios.
Violation of installation rules and vibration of the housing
The most common, but common cause of knocking is incorrect installation of the unit. If the refrigerator is not level, during operation compressor the body begins to vibrate and hit walls or nearby pieces of furniture. Even a microscopic misalignment can cause resonance, increasing the hum of the motor to the level of a loud knock.
Check the distance between the back of the device and the wall. It should be at least 5-7 centimeters for free air circulation. If the gap is smaller, thermal expansion of materials and engine vibration will cause characteristic impacts on the wall surface.
It is also worth paying attention to the floor. Linoleum, tile, or laminate flooring can be slippery and the refrigerator feet may not provide enough traction. In this case, the unit “walks” when the engine starts.
⚠️ Attention: When installing the refrigerator, never rest it only on the rear wheels or front adjustable feet. All four points must be firmly in contact with the floor to dampen vibration.
Problems with the compressor and pump motor
If external factors are excluded, most likely the source of the noise is inside the technical compartment. Compressor This is the heart of the refrigerator, and its operation should not be accompanied by metal clanging or loud banging noises. Most often, knocking indicates wear of internal parts or problems with fastening.
One of the common reasons is the failure of the shock absorbers on which the engine is suspended. Over time, the rubber dries out, and the metal casing begins to hit the frame every time you start. This creates a rhythmic knocking sound that stops when the engine reaches operating mode.
A more serious problem is water hammer in the compressor cylinder. This occurs when liquid refrigerant instead of gaseous refrigerant enters the compression chamber. This water hammer is accompanied by a sharp, one-time impact and can quickly disable the unit.
It is better to diagnose the compressor with an assistant. One person listens to the sound from behind, and the second at this time listens to the operation of the motor, placing his hand on the body (be careful, it may be hot).
Faults in the defrosting system and freezing of ice
In refrigerators with a system No Frost or drip defrosting, the problem of excess ice formation is often encountered. When the frost layer becomes too thick, the fan blades begin to touch the ice crust. This causes cracking and periodic knocking, repeated with a certain cyclicity.
Ice can accumulate not only on the evaporator, but also on the bottom of the freezer. If the drainage hole is clogged with debris or ice, the water will not drain and will freeze and form an ice plug. During thermal expansion or vibration, this layer of ice can break off and fall with a roar onto the internal elements or the bottom of the chamber.
It is also worth checking the condition of the defrost heater. If it burns out, the evaporator becomes overgrown with a “fur coat”, which interferes with the operation of the fan. In this case, the knocking will be accompanied by poor cooling of the food.
How to quickly defrost a refrigerator?
To completely defrost, unplug the appliance, open the doors and leave for at least 12-24 hours. It is strictly prohibited to speed up the process with a hairdryer or hot water - this will damage the plastic and seals.
⚠️ Attention: If you hear the fan blades hitting the ice, do not try to tear off the ice with a knife or sharp objects. You can damage the evaporator tubes, which will lead to freon leakage.
Fan wear and foreign objects
In modern models, fans provide air circulation. If there is a knocking or crackling sound in the system, it is possible that hair, threads have become wrapped around the blades, or a small object has fallen. The balancing is disrupted, and the fan begins to hit the walls of the duct.
You can determine a fan malfunction by the characteristic “trrr” sound or an intermittent hum. This often happens in the freezer, where, due to low temperatures, the lubricant in the bearings thickens and the bushings wear out faster.
Sometimes the extraneous sound is not produced by the fan itself, but by the wiring, which has gotten into the rotation zone of the blades due to vibration. In this case, it is enough to simply adjust the wiring harnesses, ensuring they are securely fixed.
☑️ Fan diagnostics
Defects in tubes and heat exchanger
Copper tubes through which the refrigerant circulates can become a source of sound during thermal expansion. When heated or cooled, the metal expands and contracts, sometimes causing clicking sounds. However, if the tubes are poorly secured, these movements are accompanied by knocking on adjacent structural elements.
This is especially common in older models, where the mounting clamps may have become loose or rusted. The vibration of a working compressor is transmitted to the entire system of tubes, causing them to beat against each other or against the cabinet body.
To eliminate this problem, you must carefully, trying not to damage the thin walls of the tubes, bend them away from each other or install additional gaskets made of rubber or foam rubber.
Comparative table of causes and symptoms
For ease of diagnosis, we have compiled a table that will help compare symptoms with possible malfunctions. This will allow you to quickly find the source of the problem.
| Sound type | Probable cause | Localization | Difficulty of repair |
|---|---|---|---|
| Rhythmic metal knocking | Wear of compressor shock absorbers | Rear lower part | Low |
| Crackling and impact of blades | Ice buildup on the evaporator | Freezer compartment | Average |
| Humm with vibration of the body | Incorrect installation, misalignment | Entire body | Minimal |
| Single loud click | Thermal expansion or relay | Inside or behind | Normal |
When you need to call a technician
Not all faults can be fixed on your own. If after checking the installation and defrosting the knocking does not stop, the problem may lie deeper. Water hammer in the compressor or valve malfunction requires the intervention of a professional with specialized equipment.
It is also worth contacting the service center if the knocking is accompanied by a change in temperature in the chambers, the appearance of oil on the floor, or constant cyclic switching on and off of the unit. Repairing a sealed circuit on your own without experience can lead to permanent equipment failure.
Remember that timely contact with a specialist often saves your budget by preventing the failure of an expensive compressor. Don't wait for a quiet knock to turn into a roar.
⚠️ Attention: If you smell burning or see sparking in the motor area, immediately unplug the refrigerator and call a technician. Operation in this condition is a fire hazard.
Noise prevention and long-lasting operation
To ensure that your refrigerator operates quietly and for a long time, follow simple operating rules. Regularly check the cleanliness of the condenser at the back, remove dust that interferes with heat transfer and causes the motor to work with overload. Make sure that the products do not touch the back wall of the chamber, causing vibration of the shelves.
Check the tightness of the door seals every six months. If the rubber band allows warm air to pass through, the compressor will work longer and harder, which increases the risk of wear of parts and noise.
Following these recommendations will extend the life of your equipment. Proper care is the best prevention of any malfunctions.
Why does the refrigerator knock only when turned on?
A knock at startup is most often associated with peak load on the compressor. At this moment, the piston group experiences maximum pressure, and if the shock absorbers are worn out or there is play in the fastenings, an impact occurs. It could also be the sound of the fan coming into operation if its bearings require lubrication.
Is it normal for the refrigerator to make sounds after it is turned off?
Yes, this is absolutely normal. After the compressor stops, the process of cooling and thermal compression of the materials occurs. Crackling and clicking noises during this period are caused by changes in the temperature of the plastic and metal. These sounds do not pose a threat to equipment.
Can a new refrigerator knock?
A new unit can make sounds during the “break-in” period. The motor needs time to develop lubricant, and the plastic needs time to adapt to temperature changes. However, a loud metallic knock in new appliances is unacceptable and may indicate a manufacturing defect or damage during transportation.