Extraneous noise, suddenly appearing in the kitchen always causes concern for the owner of household appliances. When the refrigerator is knocking, this is not just an irritating factor that interferes with a relaxing rest, but also a potential signal of a malfunction of internal mechanisms. Such sound manifestations cannot be ignored, as they can indicate both minor adjustments and serious damage to expensive components.
In this article we will analyze in detail why knocks, rumbles or periodic knocks occur during operation of the unit. You will learn to distinguish normal operating sounds from alarm signals. Understanding the nature of the noise will help you make the right decision: try to fix the problem yourself or immediately call a technician for compressor repair compressor repair.
It is worth noting that modern models, such as LG or Samsung, are equipped with inverter motors that operate much quieter than older counterparts. If your equipment makes loud noises, this is almost always an abnormality. Let's look at the main scenarios in which the unit begins to behave noisily.
Is it normal operating noise or a malfunction?
Before sounding the alarm, it is necessary to determine the nature of the sound. Many users confuse natural physical processes with breakdown. For example, the sound of bubbles bursting or a quiet gurgling sound is normal movement refrigerant through the tube system. However, the rhythmic knocking or grinding of metal on metal already requires attention.
Often owners notice that the refrigerator begins to make noise immediately after turning it on or off. This is due to the operation thermostat and starting of the engine. At the moment of start, the pistons may make a louder sound due to inertia, but it should quickly subside. If the knocking continues constantly or increases over time, this is a sign of wear of the parts.
⚠️ Attention: If you hear not just a knock, but a metallic clanging sound, accompanied by vibration of the housing, immediately unplug the device. Continuing to operate in this mode can lead to complete destruction of the compressor.
To quickly assess the situation, use the following list of signs indicating that the equipment is operating normally:
- 🔇 A quiet hum or hiss that is barely audible from a distance of one meter.
- 🌡️ Periodic turning on and off of the motor with a characteristic but quiet click of the relay.
- 💧 The sound of flowing liquid inside the chambers, which can intensify immediately after defrosting.
- 🌀 Uniform fan hum in models with the system No Frost, which does not turn into a whistle or crackling.
Installation problems and cabinet vibration
One of the most common reasons why a refrigerator knocks is improper installation. If the body of the unit is skewed or is unstable, the running motor causes resonance. The vibration is transmitted to the floor and walls, creating the effect of constant rattling or knocking of the legs on the covering.
Check the horizontal installation using a building level. Even a slight tilt can cause the door to not fit tightly and the body to vibrate. Adjustment support legs often solves the problem in a matter of minutes. In models Bosch and Indesit the legs have a threaded connection that allows you to accurately set the height.
It is also worth checking the distance to walls and furniture. If the unit is located close to cabinets, vibration can be transmitted to them, causing a response knock. Leave a gap of at least 5-10 cm on all sides for free air circulation and no contact with foreign objects.
Here are the main installation errors that lead to noise:
- 📏 Lack of horizontal position of the body, which causes frame distortion.
- 🏠 Touching the rear condenser grilles of the wall or curtains.
- 🔌 Vibration from contact with other household appliances, for example, a washing machine.
- 🪵 Installation on an uneven or sagging floor (parquet, laminate with voids).
Compressor malfunctions and start relay
If the problem is not in the installation, then most likely the problem is in the “heart” of the refrigerator - the compressor. It is this node that creates the main pressure in the system. When a refrigerator knocks during operation, worn bushings or a connecting rod mechanism inside the motor are often to blame. Over time, the metal wears out, play appears, and the piston begins to beat against the walls of the cylinder.
Particular attention should be paid to the starting relay. This small element is responsible for starting the engine. If the relay contacts are burnt or the mechanism is jammed, you may hear a loud click, followed by an attempt to start and a characteristic knocking sound. In some cases, the relay simply falls due to vibration if the fastening is loose.
| Sound type | Probable cause | Difficulty of repair | Required actions |
|---|---|---|---|
| Rhythmic metal knocking | Wear of connecting rod-piston group | High (compressor replacement) | Call a technician, pressure diagnostics |
| Loud clicking and buzzing | Starter fault relay | Low (replacement of relay) | Replacement of the relay with a similar one |
| Vibration and rattling | Loose motor fasteners | Medium (adjustment) | Tightening bolts, replacing shock absorbers |
| Whistling and knocking when starting | Problems with motor electrical | High | Diagnostics of windings |
It is important to understand that replacing a compressor is a complex process that requires evacuation of the system and refueling freon. It is impossible to perform this operation independently without special equipment. If the diagnostics showed a failure of the motor, it is better to contact a service center.
Is it possible to drive the compressor?
Transporting the refrigerator while lying down often leads to oil leakage into the refrigerant circuit. This may cause water hammer on first start-up, resulting in knocking and valve failure. Let the equipment stand upright for at least 4-8 hours before turning it on.
No Frost defrosting system and ventilation
In refrigerators with a system No Frost the fan often becomes the source of noise. The blades may touch frozen ice or a foreign object caught inside. In this case, you will hear a crackling or rhythmic knock, which intensifies when the fan is running.
It is also worth mentioning the defrost system. Occasional cracking or clicking noises may occur from plastic parts as temperature changes (thermal expansion). However, if the sound resembles the sound of falling objects, it is possible that too much ice has accumulated in the chamber defrost too much ice has accumulated, which breaks off and falls onto the heater or tray.
To eliminate noise in the ventilation system, follow these steps:
- ❄️ Completely defrost the refrigerator (at least 24 hours) to remove ice from the evaporator.
- 🌀 Check that the fan blades are clean and free of ice.
If the knocking noise resumes after defrosting, the fan bearing or its motor may have failed. In models Atlant i Stinol this is a common problem that can be solved by replacing the unit.
☑️ Fan diagnostics
Foreign objects and load on the shelves
Sometimes the reason is trivial: inside the refrigerator or freezer there are objects that move due to vibration. Glass bottles touching each other make a loud knock. Plastic containers may rattle on the shelves.
Check the stability of the glass shelves. If one of the guides is broken or the shelf is not level, it will vibrate along with the cabinet. Also pay attention to how the bottles are placed in the door - they should not touch the walls of the niche.
Here is what most often becomes the source of internal noise:
- 🍾 Glass containers standing close to each other.
- 🥣 Metal pans or molds that are not secured on the shelf.
- 🧊 Pieces of ice that have broken off from the evaporator and fallen into the water drainage chute.
- 🧊 Products frozen to the walls and vibrating during compressor operation.
⚠️ Attention: Never leave open glass jars with liquid in the freezer. When freezing, the liquid expands, the glass breaks, and fragments can damage plastic parts or get into the ventilation system.
When urgent repairs are needed
There are situations when you cannot delay repairs. If the knocking is accompanied by a lack of cold, this indicates a critical malfunction. There may be a break in the tube or a gas leak, and the compressor is running “idle”, trying to build up pressure.
Another alarming symptom is the smell of burning or scorched wiring combined with unusual sounds. This may indicate overheating of the motor windings or a short circuit in the control circuit. In such cases, operating the equipment is dangerous.
The main signs that require calling a technician:
- 🔥 The appearance of a burning or smoke smell.
- 🌡️ Complete absence of cold when the engine is running.
- 🔌 Frequent switching on and off (clocking) with a loud click.
- 💥 Loud bang or explosive sound in the rear of the unit.
Remember that timely diagnosis can save significant money. A small problem, such as replacing bushings or relays, is cheaper than replacing a burnt-out compressor or restoring a system after a leak.
FAQ: Frequently Asked Questions
Why does a new refrigerator make strange noises?
New appliances may make sounds associated with grinding in parts. Noise can also occur due to shipping bolts if they have not been removed, or due to the fact that the refrigerator did not sit sufficiently before turning on. Let it work for a few days; if the noise does not subside, check the installation.
Is it dangerous if the refrigerator hums and knocks a lot?
Yes, it is dangerous. A loud knock indicates mechanical damage to the internal parts of the compressor. Continued operation will result in permanent failure of the unit and possible refrigerant leakage. It is better to turn off the device and carry out diagnostics.
Can the level affect the knocking of the refrigerator?
Absolutely true. An incorrect level causes the frame to skew, which can cause doors to not close tightly, and the vibration of the motor increases, being transmitted to the floor and walls. Adjusting the legs is the first thing to do when noise occurs.
How often should you defrost the refrigerator to avoid knocking?
For models with manual defrosting - as ice forms (usually 1-2 times a year). For the system No Frost preventative defrosting is recommended once a year to clean the drainage and check the condition of the fan, which will prevent the appearance of unnecessary sounds.