Why the refrigerator knocks periodically: diagnostics and solutions

The situation when the refrigerator begins to make extraneous sounds always causes concern among the owners. It is especially alarming if the equipment works properly, the products do not spoil, but periodic knocking it appears and then disappears. This sound can be quiet and barely noticeable or loud, reminiscent of hammer blows, and most often it signals problems in the operation of internal mechanisms.

Before calling a technician or looking for a new unit, it is important to understand the nature of the noise. In some cases, this is a normal workflow associated with the expansion of materials or the operation of automation. However, often metal clanging or dull knocks indicate wear of parts, problems with compressor mounting or malfunctions in the refrigerant circulation system. Understanding the source of the sound is the first step to saving your budget for repairs.

In this article we will analyze in detail all the possible causes of knocking, methods of self-diagnosis and situations where professional intervention is indispensable. You will learn to distinguish safe sounds from signs of serious damage, which will help extend the life of your household appliances.

Natural causes of knocking during operation

A knock in the refrigerator does not always indicate a breakdown. Modern technology, especially models with the No Frostsystem, is equipped with many automatic systems, the operation of which can be accompanied by sound effects. Users often confuse these normal sounds with a malfunction, although in fact the unit is operating normally.

One ​​of the most common reasons is thermal expansion and contraction of materials. The inner walls of the chamber and the evaporator are made of plastic and metal, which can produce a characteristic crackling or clicking sound when the temperature changes sharply. This is absolutely normal, especially immediately after turning on the refrigerator or after the defrosting cycle, when the temperature of the parts changes most actively.

It is also worth considering the operation of the defrost system. In models with automatic defrosting, the heating element periodically turns on or the valves switch, which may be accompanied by the sounds of liquid flowing or clicks. If the knocking occurs rarely and is not accompanied by other symptoms, such as heating of the case or lack of cold, most likely your appliance is just “talking.”

It is important to note that new refrigerators may make more noise during the break-in period. Grinding in the moving parts of the compressor and stabilizing the pressure in the system can take from several days to a week. If during this time the nature of the noise does not change and does not become aggressive, there is no cause for concern.

Problems with the compressor and fan motor

If natural causes are excluded, the next candidate for inspection is the heart of the refrigerator - the compressor. It is this that creates the pressure for the circulation of the refrigerant. Periodic knocking, especially when starting or stopping the engine, often indicates wear of internal components or problems with the fastening of the unit itself.

One ​​of the common causes is wear compressor suspensions. The motor is suspended on springs inside the casing, and over time the metal gets tired or breaks. As a result, when starting up, the compressor housing begins to bang against the walls of the casing, producing a loud metallic clang. Rubber shock absorbers that dampen vibration may also wear out.

In more serious cases, knocking may indicate mechanical damage to the internal parts of the compressor, for example, the piston group. This often occurs due to water hammer when liquid freon enters the cylinder instead of gas. In such a situation, the knocking will be accompanied by vibration of the entire body of the refrigerator and, possibly, unstable cooling.

Do not forget about the fan, if it is provided for in the design of your model (usually in systems No Frost). Foreign objects caught in the blades or frozen ice may cause an intermittent knocking or humming noise. A rotating fan can touch wires or casing elements, creating a rhythmic sound.

Faults in the refrigerant circulation system

The pipeline through which the refrigerant moves is a complex system of copper tubes. Normally, the movement of freon is silent or accompanied by a quiet gurgle. However, if you hear a distinct knock or knock, this may indicate that the tubes are in contact with each other or with the walls of the refrigerator body.

When the compressor operates, vibration occurs, which is transmitted to the entire circuit. If the tubes are not secured tightly enough or the fastening has become loose over time, they begin to hit the metal parts of the housing or each other. This knocking is often periodic and intensifies at moments of maximum load on the engine.

Another reason may be a clog in the capillary tube or filter drier. When refrigerant passes through a narrowed cross-section, turbulence and pressure surges occur, which can be accompanied by sounds similar to blows or whistles. In such cases, a decrease in cooling efficiency is often observed.

It is important to check the condition of the condenser (grids at the back of the refrigerator). If it is located too close to a wall or floor, vibrations from the running compressor can be transmitted to it, causing rattling and knocking. It is enough to simply move the refrigerator away from the wall or place rubber pads under the legs of the condenser.

The influence of improper installation on the noise level

Often the reason for periodic knocking lies not in a breakdown, but in a banal violation of installation rules. A refrigerator is an appliance that requires a strictly horizontal position. If the unit is skewed, the load on the compressor is distributed unevenly, which leads to increased vibration and knocking.

Check the adjustable feet of the refrigerator. They must be unscrewed so that the body is stable and does not wobble when pressed lightly. If one of the legs does not touch the floor or, conversely, the refrigerator is skewed to one side, this will inevitably cause resonance and knocking when the motor is running.

You should also pay attention to the distance to the walls and furniture. The minimum gap should be 5-10 cm on all sides. If the refrigerator is pressed tightly against a wall or cabinets, vibration will be transmitted to them, causing rattling and increased noise. In addition, insufficient ventilation can lead to overheating of the compressor and a change in the nature of its operation.

The floor at the installation site also plays a role. Wooden or soft linoleum floors may resonate with the vibration of the refrigerator. In such cases, it is recommended to use special anti-vibration pads under the legs, which dampen vibrations and prevent the equipment from “walking.”

Diagnostics: how to determine the source of the sound

To effectively eliminate the problem, it is necessary to determine exactly where the sound is coming from. Carry out initial diagnostics, carefully listening to the operation of the unit in different modes. This will help narrow down the range of possible causes and understand whether you need to call a technician.

Try to lightly press the refrigerator body in different places. If the knocking stops or changes in tone, then the problem is vibration of the case or the panels are not fitting tightly enough. You can also gently (with caution!) hold the compressor with your hand while it is running - if the knocking noise disappears, then the problem is in its suspension.

Use the table below to quickly classify sounds and possible causes:

Pay attention to frequency. If the knocking noise only occurs when turning on or off, this narrows the search to inrush currents or thermal expansion. Constant knocking during operation often indicates mechanical friction or beating of parts.

Do-it-yourself methods for eliminating knocking

If you determine that the cause of the knocking does not require complex repairs with replacement of components, you can try to eliminate it yourself. The main rule is to act carefully and not use excessive force so as not to damage the fragile elements of the system.

Start by checking the compressor mounts. Remove the back cover (after turning off the power!) and inspect the suspension springs. If one of them comes off, it can be put back in place. If the spring breaks, it will need to be replaced, which is more difficult. Also check if the tubes are loose - they can be carefully pushed aside or secured with a clamp.

In models No Frost defrosting often helps. If the fan touches ice, turning off the refrigerator completely for 10-12 hours will allow the ice to melt. After this, the knocking should disappear. If the problem is the wear of the fan bearing, it will have to be replaced.

To reduce vibration of the case, you can use anti-vibration pads under the legs. They are sold in hardware stores and are inexpensive. Also make sure that nothing is loose inside the chambers: shelves, drawers or bottles can rattle from vibration, creating the illusion of knocking inside the unit.

When you need to call a professional technician

Despite the possibility of self-diagnosis, there are situations where the intervention of an unqualified user can only cause harm. If you are not confident in your abilities or have discovered serious mechanical damage, it is better to entrust the repair to a specialist.

Calling a technician is required if the knocking is accompanied by the following symptoms:

• ⚡ The compressor hums, but does not start, and a relay click is heard.
• 🔥 Rear the wall of the refrigerator becomes very hot or, on the contrary, remains cold.
• 💧 Traces of oil appeared around the compressor or on the floor under the equipment.
• 📉 The temperature in the chambers no longer corresponded to the set values.
• 🔊 The knocking became constant and very loud, causing shaking floor.

⚠️ Attention: If you hear a burning smell or see sparking in the compressor area, immediately unplug the refrigerator and do not try to turn it on again until the technician arrives.

Professional help is also needed if the compressor needs to be replaced or the system needs to be refilled with refrigerant. These works require special equipment, knowledge and licenses. An independent attempt to open the circuit can lead to a freon leak and final failure of the equipment.

Remember that timely repairs are often cheaper than replacing the entire unit. If your refrigerator is under warranty, any independent repair may result in denial of warranty service.

Prevention and operating rules

To reduce the risk of knocking and extend the life of the refrigerator, it is important to follow the operating rules. Regular defrosting (for models without No Frost) will prevent the build-up of ice, which can block the fan or create a load on the compressor.

Keep an eye on the loading level of the chambers. An overloaded refrigerator operates in increased mode, which increases vibration and wear of parts. Do not place hot foods inside - this causes a sharp expansion of air and a load on the cooling system, which can also cause knocking.

Regularly check the cleanliness of the condenser at the back of the refrigerator. Dust and animal hair collected in the grille impair heat transfer, causing the motor to work longer and more intensely. Cleaning with a vacuum cleaner every six months is a simple procedure that makes life much easier for your equipment.

⚠️ Attention: Characteristics and maintenance requirements may vary depending on the model and year of manufacture. Always check the official manufacturer's instructions for your specific device.

Following these simple recommendations will help you avoid most noise and knocking problems. Remember that paying close attention to the “well-being” of your refrigerator allows you to notice the problem at an early stage and solve it with minimal costs.