Sudden knocking sound in The refrigerator can turn a cozy kitchen into a source of constant irritation. This sound can be barely noticeable or deafeningly loud, rhythmic or chaotic, but in any case it signals that processes are occurring inside the unit that go beyond the norm. Most often, owners are faced with a situation where household appliances are working properly, but the characteristic sound interferes with comfortable living in the apartment.
Extraneous noise cannot be ignored, as they are often harbingers of more serious breakdowns that may require expensive repairs or complete replacement of expensive components. Understanding the nature of sound is the first step to solving the problem. In most cases, the source of noise can be determined independently, without calling a specialist, simply by listening to the nature of the sound and analyzing the operating conditions.
There are many factors that affect acoustic comfort: from a banal distortion of the housing to wear of the internal mechanisms of the compressor. It is important not to panic, but to consistently check all possible options. Vibration, resonance and mechanical wear - these are the three pillars on which most sound problems in modern household appliances rest.
Natural causes: when knocking is normal
A rumbling sound does not always indicate a breakdown. Modern models, especially those working on the No Frostsystem, can produce specific sounds during their normal operation. For example, when automatically starting a defrost cycle or switching compressor operating modes, clicks and short knocks may occur, which are absolutely normal for a working device.
Often the source of sound is thermal expansion and contraction of materials. The plastic elements of the inner chamber and the metal tubes of the evaporator may emit a characteristic crackling sound or short knocks when there is a sudden change in temperature. This is due to the physical properties of materials and does not require the intervention of specialists.
- 🔊 Clicking of the thermostat when the set temperature is reached.
- 🔊 Gurgling of refrigerant flowing through the pipeline system.
- 🔊 Noise of fans of the forced circulation system air.
It is important to understand the difference between operating noise and signs of malfunction. If the refrigerator makes a uniform hum, interrupted by occasional clicks, it is most likely operating normally. However, if rattling or rhythmic knocking is added to these sounds, increasing over time, it is necessary to carry out a more in-depth diagnosis.
⚠️ Attention: If the knocking appears only when the engine is turned on or off and lasts no more than 2-3 seconds, this is usually the operation of the starting relay or valves, which is an acceptable norm for many models.
Problems with installation and external factors
Before disassembling the unit or calling a repairman, it is necessary to exclude external factors. Very often the reason that the refrigerator is knockingis incorrect installation. An uneven floor or lack of clearance between the walls of the appliance and the furniture leads to the transfer of vibration to the body and surrounding objects.
Check the position of the legs of the refrigerator. If it is not stable, the slightest vibration of the compressor will cause the housing to sway and hit walls or furniture. Adjusting the support legs allows you to set the equipment perfectly level, which often completely eliminates the problem.
It is also worth paying attention to the contents of the shelves and doors. Glass bottles or metal containers touching each other when vibrating can create a loud knocking sound. Make sure that all objects inside are securely fixed.
☑️ Installation diagnostics
Another important aspect is the communications going to the refrigerator. The pipes at the back of the unit must not touch the wall or each other. When the compressor is operating, they begin to vibrate and, in contact with hard surfaces, harass household members with an unpleasant sound.
Malfunctions of the compressor and start relay
If external causes are excluded, and the knocking continues, most likely the problem lies in the “heart” of the refrigerator - the compressor. This is the most expensive and important component on which the circulation of the refrigerant depends. Knocking in the compressor can be caused by wear of internal parts, loose fastenings or problems with the electrical part.
One of the common causes is wear of the bushings or shock absorbers on which the motor-compressor. Over time, the rubber dries out and the metal casing begins to hit the metal casing or frame of the refrigerator. This creates a dull, rhythmic knock, which intensifies when the motor is running.
It is also worth paying attention to the starting relay. If it is faulty or loose, it may rattle or knock when electrical current passes through. In some cases, replacement of this element is required, which is a relatively simple and inexpensive procedure.
⚠️ Attention: If the compressor makes a loud metallic clanging sound immediately after turning on and then turns off, this may indicate a jammed piston group. You cannot operate such a unit - urgent repairs are required.
How to test a compressor by ear?
For an accurate diagnosis, you can use a medical stethoscope or a long screwdriver. Place the handle of the screwdriver on the compressor body and the ear on the end of the handle. This way you can localize the source of the sound: inside the motor or outside, in the mounts.
The table below shows the main types of compressor sounds and their probable causes:
| Type of sound | Probable cause | Need for repair |
|---|---|---|
| Thud | Wear of suspension shock absorbers | Average (replacing bushings) |
| Metal clanging | Destruction of internal parts | High (compressor replacement) |
| Rattling | Loosening of mounting bolts | Low (tightening fasteners) |
| Clicks at start | Malfunction of the starting relay | Medium (replacement of the relay) |
Vibration of tubes and elements of the cooling system
The cooling system is a complex circuit of copper and aluminum tubes through which the refrigerant circulates. During operation of the compressor, these tubes vibrate. If the fastenings are loose or the tubes come into contact with each other, a characteristic ringing or knocking occurs.
Often the source of noise is the capillary tube, which may touch the housing or other structural elements. Vibration is transmitted through the metal and amplified, creating a resonance effect. To eliminate this problem, you need to carefully bend the tubes or install damper pads between them.
In models with the system No Frost the evaporator may be the source of sound. During defrosting, the ice melts, and drops of water falling onto the heater or into the tray may make hissing or light impacts. This is normal, but if the sound is too loud, there may be a problem with water drainage or an ice blockage.
Sometimes knocking occurs due to the fact that the drain tube for removing condensate vibrates against the back wall of the refrigerator. It is enough to simply place a piece of soft cloth or rubber at the point of contact to eliminate the unpleasant sound.
Wear of fans in the No Frost system
Refrigerators with the system No Frost are equipped with fans that circulate cold air inside the chambers. Over time, fan bearings wear out, resulting in a humming, whining, or rhythmic knocking sound.
If your freezer fan makes a knocking sound, it may mean that ice has frozen on its blades. The ice crust interferes with free rotation, and the blades touch the body or ice. In this case, the refrigerator must be completely defrosted within 10-12 hours.
In case of mechanical wear of the bearing, the fan will have to be replaced. This is not the most difficult procedure, but it does require disassembling the interior panel of the freezer. It is important to choose a similar fan model with the appropriate dimensions and connector.
- ❄️ Check to see if ice has frozen on the fan blades.
- ❄️ Try manually turning the blades (with the refrigerator turned off) - the movement should be free.
- ❄️ Pay attention to the fastening of the fan motor - it should not be loose.
⚠️ Attention: Before any work inside the refrigerator or freezer, be sure to disconnect the device from the power supply. Working with electrical components in a damp environment is life-threatening.
Resonance of objects and interior decoration
Sometimes the source of the problem is the users themselves. Heavy objects placed on the top panel of the refrigerator (microwave ovens, jars) can resonate with the vibration of the cabinet. Even if the refrigerator itself is running quietly, objects on it can create significant noise.
Interior shelves and drawers can also be a source of knocking. If the glass shelf does not sit tightly in the guides or the plastic drawer has play, they will rattle when the compressor operates. Check all the fastenings inside the chambers.
Plastic bottles with liquid standing on the door may knock against each other. Put away unnecessary items or use organizers to keep them organized. Sometimes it is enough just to change the arrangement of products so that silence returns to the kitchen.
Do not forget about decorative elements. Magnets on the door, if there are many of them or they are metal, may rattle. Remove all foreign objects from the external surface and check if the sound has disappeared.
When you need to call a technician
There are situations when self-repair not only will not help, but can also aggravate the situation. If you have ruled out all external factors, checked the fastening of the compressor and fans, but the knocking remains, there may be a problem within the sealed circuit or in the electronics.
If the knocking is accompanied by a lack of cold, continuous operation of the compressor, or the appearance of a burning smell, immediately turn off the refrigerator and contact a service center. Delay can lead to engine combustion or leakage of all refrigerant.
Professional diagnostics require special equipment: pressure gauges, leak detectors and testers. The technician will be able to accurately determine whether the compressor needs to be replaced, refilled with freon, or the control board repaired.
Is it possible to operate the refrigerator if it is knocking?
If the knocking is caused by vibration or resonance, operation is possible. But if the sound comes from the compressor (metallic clanging), further work can lead to its complete failure.
Why does an old refrigerator knock more than a new one?
Over time, rubber shock absorbers wear out, fastenings become loose and play appears in moving parts. This is a natural process of aging equipment, which increases vibration and noise.
Does the filling level of a refrigerator affect noise?
Yes, an empty refrigerator can be noisier due to the lack of objects that absorb sound waves. However, a crowded refrigerator can interfere with air circulation, causing the compressor to work harder.
How often should you defrost the refrigerator to avoid knocking?
For systems No Frost defrosting is rarely required (as needed or 1-2 times a year for hygiene). For a drip system - every 4-6 months. Ice can block fans and cause knocking.
Is it dangerous to ignore knocking in the compressor?
Yes, it is dangerous. A knocking sound may indicate that the compressor is overloaded. This leads to increased energy consumption and the risk of fire or complete breakdown of the unit.