Situation when suddenly knocks in the refrigerator, is capable of unbalancing any owner of household appliances. The silence in the kitchen is broken by rhythmic blows, which can be barely noticeable or resemble the work of a jackhammer. In most cases, this sound indicates mechanical vibration, improper installation or the beginning of wear of the internal components of the unit.
You should not ignore extraneous sounds, as they may indicate that compressor it is working with increased load or the circulation of the refrigerant is disrupted. Understanding the nature of the noise is the first step to solving the problem and often avoids an expensive call to the repairman. In this article, we will analyze in detail why knocking occurs, how to distinguish normal operation from a breakdown, and what steps to take for diagnosis.
Independent inspection and correct diagnostics in some cases help to eliminate the problem in just a few minutes. However, it is important to act carefully so as not to damage the fragile elements of the cooling system. Let's figure out what factors most often cause the loud operation of your refrigeration equipment.
Natural causes of knocking and vibration
Knocking does not always indicate a serious breakdown. Modern models, especially those using technology No Frost, produce various sounds during normal operation. For example, periodic cracking of plastic or clicking of the thermostat is an absolutely normal phenomenon caused by the thermal expansion of materials when the temperature changes.
It is also worth considering the operation of the defrost system. When it turns on Defrost heating element or water is discharged into the drainage tray, gurgling sounds or slight knocks may occur. If the sound occurs rarely and is not of a constant mechanical nature, most likely the equipment is working properly.
⚠️ Attention: If knocking is accompanied by a sharp change in temperature in the chambers or the appearance of ice, this is no longer normal operation, but a sign of a malfunction of the defrost system or freon leak.
Often owners confuse the hum of a compressor with a real knock. Inverter compressor, unlike the classic one, it can change the tonality of the operation, creating the illusion of interruptions or shocks when switching to low speeds. Careful listening will help determine whether the sound is coming from the motor or from cabinet vibration.
Problems with installation and housing
One of the most common reasons why knocks in the refrigeratoris its incorrect location. If the unit is not level, vibration from the running motor is transmitted to the floor and walls, creating a resonating hum and shock. Checking the horizontal installation is the first thing you need to do before looking for internal damage.
Another source of noise can be the contact of the refrigerator body with furniture, walls or curtains. Even a minimum gap of 1-2 centimeters is necessary for free air circulation and vibration damping. Make sure that nothing is touching the side walls and rear grille.
- 🔧 Check the adjusting feet: they should be firmly on the floor, and the housing itself should not wobble when pressed lightly.
- 🚚 Inspect the shipping bolts: if they were not removed after purchase, the compressor will work with strong vibration.
- 📏 Move the refrigerator away from the wall at least 5-7 cm to prevent the back panel from contacting the surface.
It is important to check the internal contents of the chambers. Heavy glass shelves or bottles, touching each other or the walls, can rattle and knock to the beat of the motor. Try to remove all the food and start the empty refrigerator - if the noise disappears, the problem is solved.
Diagnostics of the compressor and start relay
If external factors are excluded, and in the refrigerator something is still knocking, most likely the problem lies in the “heart” of the unit - the compressor. Piston group the engine wears out over time, and the pistons begin to hit the cylinder walls, creating a characteristic metallic knock. This is often accompanied by difficulties with starting.
Another common reason is a malfunction of the starting relay. This small element is responsible for starting the engine. If the contacts inside the relay are burnt or the mechanism is stuck, you will hear a loud click, followed by a buzzing sound, and then another click and stop. The cycle can be repeated until the relay is replaced.
Diagnostics should be carried out carefully. With the motor running, you can carefully (without touching live parts!) put your hand on the compressor housing. If the vibration is transmitted too strongly to the housing and is accompanied by shocks from the inside, this is a sign of wear compressor suspension or internal mechanical damage.
| Sound type | Probable cause | Necessary actions |
|---|---|---|
| Metallic clanging at start | Wear of the piston group | Replacement of the compressor |
| Loud click and silence | Faulty start relay | Replacing the relay |
| Rhythmic humming with vibration | Unbalancing the motor suspension | Adjusting the springs |
| Whistling and knocking | Problems with valves | Repairing or replacing the motor |
⚠️ Attention: If you smell burning or see sparking in the compressor area, immediately unplug the refrigerator. Operation of a faulty electric motor can lead to a fire.
Knock in the No Frost system and fan
In refrigerators with the system No Frost the fan is responsible for circulating cold air. If the water in the chamber is frozen or the “fur coat” is frozen, the fan blades may touch the ice. This causes a characteristic crackling or knocking noise, which often intensifies when the door is opened (since in some models the fan stops, changing the tone of the sound).
To eliminate this problem, defrosting is often required. It is necessary to completely unplug the refrigerator, open the doors and leave it for at least 24 hours. This will allow the ice in the evaporator (which is hidden behind the back panel) to completely melt.
- ❄️ Defrosting must be complete: even a small piece of ice can interfere with rotation.
- 🌀 Check the cleanliness of the fan: after defrosting, remove the back panel and make sure that the blades rotate freely.
- 🔊 listen: listen to see if the wiring or other elements are touching moving parts.
If after defrosting the knocking resumes after a short time, the fan motor itself or its bearing may have failed. In this case, replacement of the part is required. Also, the cause may be a malfunction of the defrost sensor, due to which the ice freezes again and again.
☑️ Action plan for fan noise
Vibration of tubes and condenser
Sometimes the sound source is not inside the cameras or in the motor, but behind the unit. Copper tubes cooling systems and the condenser grill may vibrate due to compressor operation. If they are located too close to each other or to the body, a loud metallic knock occurs.
To eliminate this defect, you need to gain access to the back of the refrigerator. Carefully, trying not to bend the thin tubes (they may burst!), try to move the vibrating elements away with your hand. If when you press with your hand the noise disappears, then you need to fix the tubes in this position.
For fixation, you can use a piece of rubber, foam rubber or a special clamp. The main thing is to provide clearance between the tubes and prevent them from colliding. Sometimes it is enough to simply straighten the springy copper tube so that it no longer touches neighboring parts.
Also check the water collection tray above the compressor. If it is loose or deformed, it will rattle. Place a soft pad under it or slightly bend the fasteners.
Danger of self-repairing pipes
Be extremely careful! The copper tubes are filled with refrigerant under pressure. If you accidentally break the tube or damage the solder, freon will escape and the refrigerator will stop freezing. Charging the system is a complex and expensive process that requires special equipment. If you are not confident in your abilities, it is better not to touch the tubes with your hands.
When you need to call a specialist
There are situations when self-repair is not only useless, but also dangerous. If knocking in the refrigerator due to water hammer in the compressor (liquid freon entering the cylinder), this requires qualified intervention. The technician will have to find the reason why the freon does not have time to evaporate (often this is a clogged capillary tube or a malfunction of the expansion valve).
Also, the help of a specialist is needed if you hear a knock, but the refrigerator does not freeze. This is a sure sign that the compressor is running dry or the tightness system is broken. Attempts to “reanimate” such a unit with blows to the housing can completely finish off the motor.
In addition, if the equipment is under warranty, any independent opening of the seals will lead to loss of warranty obligations. In this case, the only right decision is to contact an authorized service center.
⚠️ Attention: Parts and designs of refrigerators from different brands (Indesit, Bosch, LG, Samsung) may differ significantly. What is easily repaired in one model may require complete disassembly of the case in another. Always check the technical documentation.
Noise prevention and equipment durability
If the problem “knocking in the refrigerator” has not returned, it is important to follow the operating rules. Defrost your appliances regularly (even the No Frost system is recommended to be washed and dried once a year), keep the condenser at the back clean and do not overload the shelves with food.
Timely replacement of rubber seals on the doors also affects the operation of the refrigerator. If the rubber band does not retain heat, the compressor is forced to work almost non-stop, which accelerates its wear and increases the likelihood of knocking and vibrations.
Remember that quiet operation of the refrigerator is a sign of the serviceability of all its components. Paying attention to the first signs of noise allows you to eliminate the problem at an early stage, preserving your budget and products.
Why did the refrigerator start knocking after defrosting?
If the knocking appeared immediately after defrosting, perhaps you did not dry the unit well enough, and water got into the pan above the compressor, causing boiling and gurgling. The fan could also have moved. Let the refrigerator run empty for several hours - if the sound does not go away, check if the evaporator tubes have frozen.
Is it possible to operate the refrigerator if it is knocking?
Short-term operation is possible if it is just vibration of the case. But if the compressor or start relay knocks, prolonged operation will lead to complete failure of the motor. It is better to carry out diagnostics right away.
Is compressor repair very different from different brands?
The operating principle of all piston compressors is the same, but the seats, power and type of refrigerant may differ. Replacement requires a professional tool for soldering and vacuuming the system, regardless of the brand (Atlant, Beko, Liebherr).
What to do if the knocking appears at night?
At night, extraneous sounds are heard better. Try to determine the rhythm: if the knocking is rhythmic and coincides with the motor turning on, this is mechanics. If it is chaotic, perhaps something has fallen inside or the dishes are rattling. Not leave the problem until the morning, if the sound is very loud - it is better to turn off the device until the technician arrives.