A sudden knock in the refrigerator can turn a quiet evening into a test for the nervous system. This obsessive rhythmic sound, which fades away and then appears again, is often the first harbinger of a serious breakdown or a sign of wear of parts. Many owners of household appliances mistakenly believe that noise is a normal part of operation, however sharp metal impacts or dull bass are rarely harmless.
Refrigeration equipment works on the principle of compression and expansion of the refrigerant, which is inevitably accompanied by vibration and sound, but the nature of these manifestations changes with the time. If a previously quiet person begins to make sounds reminiscent of hammer blows or rolling stones, this cannot be ignored. Diagnosing the source of the noise is the first step to preventing costly repairs that may be required if the compressor fails. Indesit or Bosch began to make sounds reminiscent of hammer blows or rolling stones, this cannot be ignored. Diagnosing the source of the noise is the first step to preventing costly repairs that may be required if your compressor fails.
In this article we will analyze in detail the mechanics of the occurrence of extraneous sounds, dividing them into design features and real malfunctions. Understanding the nature of sound will help you make the right decision: call a specialist, carry out adjustments yourself, or simply come to terms with the operating features of your model.
Anatomy of noise: how to distinguish normal from pathology
The first thing to do when a knocking noise appears is to carry out an initial acoustic diagnosis. Modern refrigerators, especially models with the No Frostsystem, produce a whole range of sounds during operation. This could be the sound of flowing water, cracking plastic, or the hum of a motor. A smooth, monotonous hum is considered normal, which can periodically intensify and subside.
Pathological knocking is often accompanied by vibration of the housing or individual panels. If you put your hand on the wall of the unit and feel rhythmic shocks synchronous with the sound, then the problem lies in the mechanical part. A distinctive feature of a critical malfunction is the appearance of a knock precisely at the moment the compressor starts or stopswhen the load on the components is maximum.
It is important to take into account the age of the equipment. Older models are characterized by wear of rubber shock absorbers, which leads to vibration transfer to the metal body. New units may “crack” due to thermal expansion of materials, which is normal, but requires time for grinding in parts.
- 🔊 Smooth hum: a sign of normal operation of the compressor, does not require intervention.
- 🔨 Rhythmic knocking: indicates runout of internal parts or a problem with the motor mounting.
- 💧 Gurgling: normal sound of freon circulating through the system pipes.
- 🔌 Click at start: operation of the start relay, but if there are a lot of clicks and the engine does not start, this is a breakdown.
You should not panic at the first unusual sound, but it is dangerous to leave the situation unattended. If the noise increases or its tone changes, it is necessary to move on to a deeper analysis.
External factors: when the refrigerator has nothing to do with it
Before disassembling the back panel and checking the insides, you should exclude trivial reasons related to the installation and placement of equipment. Often the source of annoying knocking is not the unit itself, but its interaction with the surrounding space. Vibration from a running motor is transmitted to the floor or walls, causing resonance.
Check whether the refrigerator is touching the walls of the kitchen unit, curtains or nearby objects. Even the slightest touch can turn a slight vibration into a loud rattling sound. It is also worth inspecting the space around: sometimes foreign objects get into the gap between the case and the wall, which begin to rattle when the equipment is operating.
⚠️ Attention: Never move the refrigerator close to the wall. For normal air circulation and vibration reduction, a gap of at least 5-7 cm is required from the back wall to the surface.
Pay special attention to the horizontal installation. If the legs are unevenly unscrewed, the housing warps, which leads to the compressor being skewed and causing knocking. Adjusting the feet is a simple procedure, but is critical to the longevity of the machine. Use a building level to check.
If the equipment is installed on linoleum or slippery tiles, it may “ride” slightly when starting the engine, hitting obstacles. In this case, special anti-vibration pads under the legs will help, which dampen vibrations.
Compressor: the heart of the refrigerator and the source of problems
The compressor is the most important and noisy component of the refrigerator. It is this that creates the pressure necessary for the circulation of the refrigerant. If the knocking noise comes directly from the engine located in the lower rear, the reasons may be serious. The internal suspension of the compressor is made on springs, which can stretch or burst over time.
When the internal spring breaks, the metal cylinder begins to hit the walls of the casing, producing a loud metallic clang, especially during startup. This requires replacing the compressor or having it professionally rebuilt, which is impossible to do at home. Also, a knock can be caused by a worn bearing or piston group.
Another reason is hydraulic hammer. If liquid freon enters the system instead of gaseous, a sharp shock occurs during compression. This often happens when the filling is incorrect or the thermostat malfunctions, when the refrigerant does not have time to evaporate.
| Type of sound | Probable cause | Difficulty of repair | Need a technician |
|---|---|---|---|
| Metal clanging at start | Breakage of suspension spring | High | Mandatory |
| Thud knock inside body | Wear of piston group | Critical | Mandatory |
| Vibration and bounce | Touching of tubes on body | Low | Desirable |
| Rhythmic beats | Valve malfunction | Medium | Required |
Diagnostics of the compressor requires caution. If you hear the engine humming but not starting, and then you hear a clicking and knocking noise, the shaft may be stuck. In this case, further attempts to turn on may lead to burnout of the winding.
Is it possible to ride on a refrigerator?
Transporting the refrigerator in a lying position often causes the compressor to knock. Oil flows into the circuit, and a hydraulic shock occurs upon startup. Let the equipment stand upright for at least 24 hours before turning it on.
Ventilation and No Frost system
In refrigerators with an automatic defrosting system, a fan is responsible for circulating cold air. If you hear a crackling noise or a noise that sounds like a propeller, this is most likely the problem. The fan blades may touch ice frozen on the walls of the chamber.
This happens when the tightness of the door seal is broken or the door is often opened. Humid air gets inside, freezes on the evaporator, and the overgrown ice begins to interfere with the rotation of the blades. As a result, a characteristic cracking or knocking sound is heard.
To eliminate the problem, it is often enough to completely defrost the refrigerator. Leave the unit turned off with the doors open for 10-12 hours. If after switching on the sound disappears, then the cause was ice. If the noise remains, the bearings of the fan motor may have worn out or its impeller has been damaged.
- ❄️ Ice on the evaporator: requires complete defrosting of the system.
- 🌀 Wear of the bushing: the fan begins to play and knock on the housing.
- 🧊 Frozen drainage: water does not drain away and freezes, creating obstacles.
- 🔌 Dry stroke: fan operation without air flow due to clogged filters.
In some models Samsung or LG the fans are located in a special box, and you can only get to them by removing the back panel of the freezer. Be careful when removing plastic elements - they become brittle in the cold.
Foreign objects and fasteners
Sometimes the reason for the knocking turns out to be ridiculously simple. During operation, small objects may fall into the housing or technical compartments. Coins, buttons, bottle caps that fall behind the refrigerator, when vibrated, begin to rattle and knock on metal surfaces.
It is also worth checking the compressor mounts. Over time, the bolts holding the motor to the frame may become loose. As a result, during operation, the engine begins to “walk” and hit adjacent tubes or casing walls. Tightening the fasteners often solves the problem.
Pay attention to the shelves and drawers inside the chambers. If they are not fully seated in the guides or are askew, vibration from the compressor will cause them to rattle. This creates the illusion that the refrigerator itself is broken.
☑️ Checking external causes of noise
Do not forget about the condenser grid at the back. If it is deformed and touches the body, it will cause a loud metallic knock. Carefully bend the grilles with your fingers (with the device turned off!), ensuring a gap.
Diagnostics and elimination methods
To accurately determine the source of the knock, use the exclusion method. First, make sure the refrigerator is level and not touching anything. Then listen at what moment the sound appears: when the engine is running, when it stops, or constantly.
If the knocking is mechanical and comes from the compressor, try to carefully (observing safety precautions!) press the motor casing with your hand. If the sound changes or disappears, the vibration is being transmitted to the housing. In this case, installing additional rubber gaskets under the compressor feet will help.
⚠️ Attention: Carry out all internal diagnostics and repair work only with the power supply completely disconnected from the network. Touching live parts or moving mechanisms under voltage is dangerous to life!
If you find that the refrigerant tubes are in contact with each other or with the wall, they must be carefully moved apart. Do this with minimal force, as copper breaks easily, and puncturing the tube will lead to freon leakage.
In the case where simple methods did not help, and the knocking continues, most likely the problem lies deep within the unit. Self-repairing a compressor or replacing a fan in hard-to-reach places requires special tools and skills.
When you need to call a specialist
There are a number of situations when self-repair is not only ineffective, but also dangerous. If the knocking is accompanied by a cessation of cooling, the appearance of a burning smell, or attempts to start the engine without results, call a specialist.
A professional technician has the necessary equipment to evacuate the system, refill with freon and diagnose the electrical part. An attempt to replace the compressor yourself without sealing the system will lead to rapid failure of the new part.
In addition, breaking the seals or carelessly tampering with the design may void your warranty. If the equipment is new, any knock is a reason to contact a service center, and not to pick at it yourself with a screwdriver.
Frequently asked questions (FAQ)
Why did the refrigerator start knocking after defrosting?
This may be due to the fact that the ice, which previously absorbed vibration or fixed parts, has melted, and now the loose elements started to move. It is also possible that water got into the electrical contacts or on the fan bearings, which caused corrosion or temporary imbalance.
Is it normal for a new refrigerator to make sounds?
Yes, in the first weeks of operation, grinding in of parts, expansion of plastic and adjustment of temperature conditions is possible. However, a loud metallic knock is not the norm, even for new equipment. Let the refrigerator operate for 2-3 days; if the noise does not subside, contact the store.
Is it possible to (continue operation) if the refrigerator is knocking?
If the knocking is weak and caused by vibration of the dishes or touching the body, you can operate. But if the knocking comes from the compressor, prolonged operation in this mode will lead to its destruction. It is better to eliminate the cause promptly.
How often do you need to change the lubricant in the compressor?
Modern hermetic compressors do not require oil changes during their entire service life. They are designed to operate without maintenance. If the oil needs to be changed, it means that the compressor is already faulty or has been opened, which makes its further operation impractical.
Does the voltage in the network affect the appearance of knocking?
Low voltage can make it difficult to start the compressor, causing humming and starting attempts, which are accompanied by clicks and knocks. If the voltage in your network fluctuates, it is recommended to use a stabilizer to protect equipment.