Extraneous sounds in household appliances refrigerator is not just an irritating factor, but also an important signal about the state of the equipment. If your the refrigerator makes knocking noises, this cannot be ignored, since mechanical noise may hide a serious breakdown of the unit. Unlike the uniform hum of a motor, knocking often indicates a malfunction of the moving parts or an imbalance in the system.
Modern models, be it Indesit, Bosch or Atlantare designed to operate as quietly as possible. The appearance of sharp, rhythmic or chaotic blows inside the body requires an immediate response from the owner. In this article, we will analyze in detail the physics of noise, diagnose the main components and determine when you can handle it yourself and when you need to call a specialist.
The first thing to do when noise appears is to determine its nature. The knocking can be dull, loud, intermittent or constant. Understanding the nature of the sound will help narrow the range of possible malfunctions and avoid unnecessary expenses for diagnostics. If the knocking is accompanied by a sharp increase in temperature in the chambers, operation of the device should be stopped immediately.
Natural causes of knocking in the refrigeration chamber
Knocking does not always indicate a breakdown. During the cyclic operation of the refrigeration circuit, physical processes occur that may be accompanied by sound effects. Owners are often frightened by loud bangs, not knowing that this is normal for certain stages of system operation.
The main cause of natural noise is thermal expansion and contraction of materials. Internal plastic panels, the evaporator and the circuit tubes change their geometry under the influence of temperature changes. When the refrigerator goes into operation or, conversely, defrosts, a characteristic crack or click is heard, reminiscent of light blows.
It is also worth considering the operation of the system No Frost. In such models, the fan periodically turns on and starts the defrost cycle. At this point, the sound of ice or snow falling from the fan blades may be heard if the freezing was uneven. This is an absolutely normal situation that does not require intervention.
- 🔹 Thermal expansion of the plastic case and internal shelves.
- 🔹 Flow of refrigerant through the tubes (gurgling, turning into light blows).
- 🔹 Falling pieces of ice during automatic defrosting.
- 🔹 Operation of pressure relief valves in the compressor at startup.
⚠️ Attention: If after manual defrosting (defrosting) the knocking does not stop, then the reason lies deeper than just frozen ice.
It is important to distinguish between isolated sounds and a rhythmic series of beats. Single clicks every 20-40 minutes are most often associated with the thermostat or thermal expansion. If the refrigerator is knocking constantly or with a high frequency, it is necessary to move on to technical diagnostics of the components.
Diagnostics of the compressor: motor-compressor as a source of noise
The heart of any refrigerator is the compressor. It is he who ensures the circulation of freon in the system. If the knocking noise comes specifically from the motor located at the lower rear of the unit, the problem may be serious. The engine operates under high pressure, and any violations in its mechanics are immediately reflected in the acoustics.
One of the common causes of knocking is wear or breakage of the internal compressor valves. In this case, the gas, when compressed, begins to “bypass” back, creating characteristic shocks. It is also possible that the piston group or connecting rods may wear out, which leads to parts hitting the cylinder walls. In such cases, the engine usually gets very hot and hums louder than usual.
Another option is destruction of the engine mount. The compressor is mounted on springs or rubber shock absorbers to dampen vibrations. If these elements wear out or burst, the metal body of the engine begins to bang against the frame or other pipes every time you start and stop. This creates a loud metallic clang.
For accurate diagnosis, you need to remove the back cover and carefully listen to the operating unit (observing safety precautions). If, when you touch the compressor housing, vibration is transmitted unevenly, and the motor itself jerks, most likely there is a problem in the fastening or internal mechanics.
Problems with the fan in No Frost systems
In refrigerators with the system No Frost the fan is responsible for circulating cold air. It is located either in the freezer or in a special compartment behind the back wall. If the refrigerator makes knocking noisesthe blade sounds like a rattle or hits an obstacle, in 90% of cases this particular unit is to blame.
Over time, ice may build up on the fan axis or blades. This occurs due to a leak in the door seals or a malfunction of the defrost system. The ice crust shifts the balancing, and the blades begin to touch the casing walls or frozen snow, producing a loud knock.
Another reason is wear of the plain bearings or fan bushings. When the lubricant dries, the axle begins to play, and the rotating element hits the body. It is also possible that foreign objects (pieces of food, labels) get into the rotation zone of the blades.
- 🔹 Ice freezing on the blades or fan axis.
- 🔹 Drying of the lubricant and wear of the rotation sleeve.
- 🔹 Deformation of the blades from overheating or mechanical impact.
- 🔹 Loosening the fastening of the fan itself to the evaporator body.
To check this version, you need to get to the fan (usually you need to remove the back panel in the freezer). If you feel jamming or hear a crunching sound when turning by hand, the part must be replaced. Sometimes completely defrosting the refrigerator within 24 hours helps if the problem is caused only by ice.
Is it possible to lubricate the fan?
Lubricating a regular household fan in the refrigerator with WD-40 oil or machine oil is not recommended. These compounds can corrode the plastic or evaporate at low temperatures, leaving the assembly dry. It is better to replace the bushing or the entire assembly.
Malfunctions of the evaporator and capillary tube
The evaporator is a radiator hidden behind the back wall inside the chamber where freon boils. A capillary tube supplies refrigerant to it. If you hear sounds that sound like metal objects hitting each other inside the walls, the cause may be a violation of the fastening of these elements.
When the compressor vibrates, the tubes may move and touch each other or the walls of the housing. This happens especially often after transporting the refrigerator if it was not securely fixed. Thin copper tubes vibrate and make a rhythmic knock.
In more rare cases, a blockage of the capillary system or the formation of an “ice plug” occurs. The pressure in the system increases sharply, and the liquid, breaking through the blockage, creates water hammer, which sounds like strong blows. This is a dangerous condition that requires the intervention of a specialist with a vacuum pump.
| Sound type | Probable cause | Danger | Actions |
|---|---|---|---|
| Rhythmic clattering | The fan touches the ice | Medium (the motor will burn out) | Defrosting, replacing the fan |
| Loud clanging at start | The suspension is broken compressor | High (motor output) | Replacement of shock absorbers |
| Single pops | Thermal expansion | No | Observation |
| Whistling and blows | Freon leakage / blockage | Critical | Call a technician |
To eliminate tube vibration, sometimes it is enough to be careful (being careful not to pinch the copper) move them apart or install additional rubber gaskets. However, if you are not confident in your abilities, it is better not to touch the circuit, as damage to it will lead to freon leakage.
External factors and incorrect installation
Before disassembling the equipment, it is worth eliminating trivial reasons. Often the refrigerator is knocking due to improper location or contact with surrounding objects. Vibration from a running motor is transmitted to the body and can resonate with nearby objects.
Check whether the refrigerator is touching the wall, furniture or curtains. Even a minimum clearance of 1-2 cm may not be sufficient if the housing vibrates. Also make sure the floor under the refrigerator is level. If one of the legs is not firmly on the floor, the misalignment causes increased vibration and knocking.
☑️ Checking the installation of the refrigerator
Another source of noise is objects inside the cameras. Glass bottles or jars standing close to each other or to the wall begin to rattle and knock when the shelves vibrate. Sometimes the sound is so strong that it is confused with a breakdown of equipment.
⚠️ Attention: Make sure that the refrigerator is on a solid base. Soft rugs or linoleum with uneven surfaces can increase vibration, creating the effect of a “jumping” compressor.
It is also worth checking the rear grille (condenser). If it is deformed and pressed against the body or tubes, it will ring when the cooling fan operates (if this model has one) or from vibration of the unit itself. Carefully straighten the grill bars, moving them away from the metal parts.
Do-it-yourself methods for eliminating knocking
If you determine that the cause of the knocking does not require complex repairs with soldering pipes or replacing the compressor, you can try to fix the problem yourself. Most vibration and fan problems can be solved with basic tools.
First, completely defrost the refrigerator. Leave it turned off for a day with the doors open. This will help eliminate ice jams in the system No Frost and check if the knocking goes away. If after turning on the sound returns after a few hours or days, there is a mechanical problem.
If the fan is knocking, it must be removed and cleaned of ice and dirt. Check for ease of rotation. If there is play in the axis, you can try to replace the bushing, but it is easier to buy a new fan - they are inexpensive and universal for many models. When installing a new fan, make sure that the wires do not get under the blades.
In the case of vibration of the tubes or housing, use vibration-isolating materials. Special anti-vibration pads under the feet or rubber washers at the compressor mounting points can work wonders. The main thing is not to use materials that are afraid of moisture and low temperatures.
When you need to call a professional technician
Despite the desire to save money, there are situations when self-repair can lead to permanent breakdown of the equipment. If The refrigerator makes knocking noisesrelated to the operation of the compressor (internal valve knocking, piston beating), you cannot cope with this on your own. The entire motor-compressor needs to be replaced.
A technician is also needed if there is a suspicion of a freon leak or a clogged capillary system. These problems are accompanied not only by knocking, but also by changes in temperature. An independent attempt to “clean” the system or top up freon without evacuation will lead to damage to the oil and compressor.
In addition, if the refrigerator is under warranty, any intervention in the design (removing seals, disassembling the compressor compartment) will void the manufacturer’s warranty obligations. In this case, the only correct solution is to contact an authorized service center.
Remember that timely repairs are often cheaper than replacing the entire unit. If you hear unusual sounds, do not wait until the refrigerator stops freezing. Early diagnostics will save your products and budget.
Frequently asked questions (FAQ)
Why does the refrigerator make knocking noises immediately after turning on?
A knocking sound at startup is often associated with a water hammer in the compressor (liquid freon enters the cylinder) or with a sharp start of the engine due to a faulty start relay. This may also be a consequence of a broken motor suspension, which hits the body as it gains speed.
Is it dangerous to continue to operate a knocking refrigerator?
If the knocking is caused by vibration or ice, it is temporarily safe. But if the compressor is knocking (mechanical wear), then further work will lead to its jamming and complete failure. It’s not worth risking an expensive component.
Can a new refrigerator knock?
Yes, during the break-in period (the first days of operation) knocking is possible from thermal expansion of materials and grinding in of parts. Also, the new refrigerator could receive microcracks during transportation, which will appear later. If the knocking does not go away after a week, this is a reason for service.
How to distinguish the knocking of a compressor from the knocking of a fan?
The knocking of a fan is normal, crackling and depends on the operation of the No Frost system (it may appear or disappear). The knock of the compressor is more dull, metallic, often coincides with the moment the engine starts or stops and is accompanied by strong vibration of the housing in the lower part.
How much does it cost to eliminate knocking in the service?
The price depends on the cause. Replacing the fan or gaskets is relatively inexpensive. If a compressor replacement or repair of the circulation system is required, the cost can be up to 50-70% of the price of a new refrigerator. The technician will tell you the exact amount after diagnosis.