A sudden loud knock in the refrigerator can disturb the peace in any apartment, especially if it happens at night. Extraordinary sounds often indicates that processes are occurring inside the system that require your immediate attention. Ignoring the problem can lead to more serious damage and expensive repairs.
Many users mistakenly believe that refrigeration equipment should work absolutely silently, but this is not entirely true. The normal operating process is accompanied by a quiet hum, gurgling of freon and periodic clicking of the relay. However, if the unit begins to make loud knocks, reminiscent of a jackhammer, or a strong metallic clang, this is already beyond the norm.
In this article we will analyze in detail all the possible causes of knocking, from basic installation errors to complex technical malfunctions. You will learn in which cases you can handle it yourself, and when you need to call a specialist. It is critical not to ignore strong vibrations of the compressor, as this can lead to ruptured tubes and leakage of refrigerant.
Primary diagnosis: installation and vibration of the case
Before you panic and look for a phone number service center, it is necessary to exclude the most common but common causes. Often loud knocking occurs due to the incorrect position of the refrigerator body relative to the floor. If the unit is unstable, the operating compressor causes resonance, causing the entire housing to rattle and hit walls or furniture.
Carefully inspect the area around the equipment. The gap between the back of the refrigerator and the wall should be sufficient for air circulation. If the case touches a wall, it will make a dull thud when it vibrates. Also check whether the internal shelves or products are touching each other, which may rattle due to the operation of the motor.
⚠️ Attention: If the refrigerator is placed on an uneven floor, the vibration of the compressor increases significantly. This not only creates noise, but also leads to accelerated wear of the engine bearings.
To fix the problem, it is necessary to level the equipment. The bottom of the refrigerator usually has adjustable feet. By rotating them, achieve a stable position in which the unit does not wobble with a slight push. Use a building level for precise adjustments.
Compressor malfunctions: when the motor requires attention
If everything is in order with the installation, but the refrigerator is knocking As before, the problem may lie in the heart of the unit - the compressor. It is this unit that is responsible for the circulation of the refrigerant. Over time, engine parts wear out and it starts to run louder. A characteristic metallic knock often indicates wear of internal valves or bearings.
In modern models with inverter compressors the noise may be less noticeable, but if a clear knock is heard, this is an alarming signal. In older single-compressor models, the starting relay often fails. It may click, but if the sound develops into frequent crackling or banging, it means that the mechanism is stuck or burned out.
It is also worth paying attention to the mounting bolts of the compressor itself. Due to constant vibration, they can weaken, and the engine will begin to “walk” inside the housing, hitting the walls of the casing. In this case, it is enough to simply tighten the fasteners, but this must be done carefully so as not to strip the threads.
How to distinguish the knock of a compressor from other sounds?
The knock of a compressor is usually rhythmic and coincides with the moment the engine is turned on or off. If the sound appears only at startup and quickly subsides, this may be normal valve operation. Constant clanging indicates mechanical damage.
Problems with the No Frost system and fan
Owners of refrigerators with the system No Frost often encounter noise that is absent in models with a drip defrosting system. Such units are equipped with fans that circulate cold air. If the fan begins to hum or knock, this is usually due to freezing or foreign objects.
Ice growing on the fan blades or on the walls of the evaporator can interfere with rotation. As a result, the blades touch the ice, producing a characteristic crackling or knocking sound. This often happens if the door seal is broken or defrosting is rarely carried out (if it is provided for in the instructions for your model).
In addition, the rotating elements may touch wires or fasteners if they have moved out of their places. In this case, you will need to disassemble the back panel of the freezer or refrigerator for visual inspection. Be careful: before any manipulations inside the chambers, be sure to disconnect the device from the network.
The influence of contents and internal fittings
Sometimes the source of noise turns out to be surprisingly simple. A loud knock can be made by itself dishes or products standing on the shelves. Glass bottles, coming into contact with each other due to vibration, can ring, and plastic containers can hit the walls.
Check the door shelves. If they are overloaded with heavy cans, they may make noise when opening or closing, or due to the vibration of the motor. Pay special attention to egg trays and bottle holders - loose objects in them often become a source of annoying noise.
Also inspect the drawers. If they are not fully inserted into the guides or their wheels are worn out, they may rattle when air moves or vibrates. Take out all the contents and listen to the operation of the refrigerator when empty - this will help localize the problem.
☑️ Checking the internal space
Table for diagnosing sounds and their causes
For ease of identifying the malfunction, we have compiled a summary table. It will help you compare the nature of the sound with the probable cause.
| Sound type | Probable cause | Difficulty of eliminating |
|---|---|---|
| Thud knocking when starting | Normal piston operation group | Not required |
| Metal clanging | Loose compressor fastenings | Low |
| Crackling and grinding | Ice getting into the fan (No Frost) | Medium |
| Frequent clicking | Start relay malfunction | High |
| Case rattling | Incorrect installation, touching walls | Low |
By analyzing the data from the table, you can initially assess the situation. If the sound matches the last point, you can easily do it yourself. If we are talking about relays or internal mechanical damage, it is better not to take risks.
When you need to call a specialist
There are situations when independent repair refrigeration equipment is not only ineffective, but also dangerous. If, after eliminating external factors (leveling, checking products), the loud knocking does not stop, the problem probably lies deep in the system.
A particularly alarming symptom is a change in the nature of the compressor operation: it can turn on for a couple of seconds, make a knock, and immediately turn off. This indicates a hydraulic shock in the system or a jammed motor. Attempts to start it many times can finally finish off the unit.
⚠️ Attention: Never try to open a sealed circuit yourself or change the compressor without special equipment. This requires evacuation of the system and charging with freon, which is impossible to do at home.
You also need professional help if you hear hissing combined with knocking. This may indicate a refrigerant leak. Inhaling freon vapors in a closed room is harmful to health, and operating equipment without gas will cause the compressor to burn out.
Noise prevention and proper care
In order refrigerator to serve for a long time and quietly, it is important to follow the operating rules. Regularly check the cleanliness of the condenser (grids at the back), as dust and animal hair worsen heat transfer, causing the motor to work with overload and increased noise.
Monitor the condition of the rubber seals on the doors. If they become dry or dirty, the door does not close tightly, warm air enters the chamber, and the No Frost system or compressor begins to work more intensely, creating more noise. Wipe the seals with a soft cloth.
Do not overload the shelves with heavy objects and ensure the even distribution of products. This will reduce the vibration load on the housing. Periodically check the tightness of the fasteners if your refrigerator is on a vibrating floor or in an area of heavy traffic.
Is it possible to lubricate the compressor?
It is strictly forbidden to lubricate the compressor from the outside or try to add oil through the holes. Inside, a special compressor oil mixed with freon is used, and the ingress of foreign substances or an imbalance will lead to breakdown.
Frequently asked questions (FAQ)
Why does a new refrigerator knock loudly when first turned on?
When first started, the compressor may work in increased mode, picking up the temperature. It is also possible for the shipping bolts to vibrate if they are not removed (although modern models are often supplied without them). If the knocking does not go away after 24 hours, contact the store.
Is it normal for the refrigerator to click after it is turned off?
Yes, this is absolutely normal. The clicking sounds are produced by a thermal relay or by the expanding/contracting plastic of the housing due to temperature changes. This is not a sign of a malfunction.
Can a refrigerator knock due to power surges?
Power surges can cause a hum, but are rarely the cause of a mechanical knock. However, unstable power can cause the start relay to malfunction, causing frequent clicking and starting attempts.
What to do if the knocking noise appears after defrosting?
Make sure that you have completely removed water and ice from the fan pan. If there is ice left inside, it could shift and begin to interfere with the blades. Let the refrigerator stand turned off for a few more hours.
Does the filling level of the refrigerator affect the noise?
An empty refrigerator may be noisier due to the lack of sound absorption by the food. Full shelves dampen vibration. However, overflow, which interferes with air circulation, will cause the motor to work louder.