Every owner of household appliances sooner or later wonders: why does the refrigerator make sounds that are sometimes frightening with their volume or unusualness? Operation of the refrigeration unit inextricably linked with the physical processes of compression and expansion of the refrigerant, as well as the movement of mechanical parts. The sound waves that we hear are a direct consequence of these processes, but their character can change dramatically depending on the serviceability of the components.
In normal mode modern compressors they work quite quietly, creating only an even, barely noticeable hum. However, if you hear gurgling noises, loud clicks, or metallic clanging sounds, this is a signal that should not be ignored. Understanding exactly how sound is generated inside the case will help you distinguish normal operation of the equipment from a serious breakdown that requires the intervention of a technician.
It is important to understand that complete absence of sound in a working refrigerator is just as suspicious as excessive noise, since this may indicate a stoppage compressor. In this article we will analyze in detail the acoustic map of your refrigerator so that you can accurately diagnose the condition of the device.
Physics of sound: how noise is generated in the compressor
The heart of any refrigerator is compressorwhich is a sealed an electric motor that pumps refrigerant through the system. It is in this unit that the main noise level is created, which is transmitted through the housing to the outside. Inside the compressor casing, pistons or a spiral (in inverter models) perform reciprocating movements, creating vibration.
A sound wave occurs due to a sharp change in gas pressure and mechanical impact of parts. When the motor starts, it overcomes static friction and pressure in the system, which causes a characteristic hum. Inverter models they work differently: they do not turn off completely, but only change the rotation speed, so the sound in them is more uniform and quiet, without sudden starting jerks.
Mufflers, installed on the suction and discharge pipes, are designed to dampen freon pulsation. If these elements are damaged or missing, you will hear a distinct metal rattling sound. Shock absorbers also play an important role, on which the compressor itself is suspended inside the casing - their wear leads to the transfer of vibration to the metal case.
⚠️ Attention: If you hear a loud metallic knock, similar to hammer blows, immediately unplug the device. This may indicate the destruction of the internal suspension of the compressor or the entry of a foreign object into the working chamber.
For a better understanding of the sources of sound, let's look at the main components involved in its creation:
- 🔊 Electric motor: creates the main low-frequency hum due to the rotation of the rotor.
- 🔊 Valve group: makes clicks when the valves open and close.
- 🔊 Refrigerant: moving freon creates sounds of liquid flow and gurgling.
Refrigerant acoustics: why does the refrigerator gurgle
One of the most common questions from users is the cause of gurgling sounds. Refrigerant circulation through the evaporator and condenser tubes - this is a continuous process, which is accompanied by phase transitions of the substance from the liquid to the gaseous state and back. It is these transitions that we hear as water overflows or seething.
Unlike the mechanical noise of a compressor, the sound of freon movement can persist even after the motor has turned off. This occurs due to equalization of pressure in the system: the remaining liquid refrigerant flows into the lower sections of the circuit, creating a characteristic “slurping” sound. In No Frost systems this sound may be more pronounced due to the complex branched network of tubes.
If the refrigerator makes sounds of running water, this is usually normal. However, if a hissing sound is added to the gurgling noise, this may indicate a freon leak. At the point of depressurization, gas escapes under pressure, creating a whistling sound that is difficult to miss. Also, hissing may occur during operation capillary tubeif there is a blockage in the system.
The ambient temperature also affects the acoustics. In hot weather, the compressor works harder, the pressure in the system is higher, and the circulation sounds become louder and more distinct. This is a normal situation and does not require repair.
Mechanical reasons: vibration and resonance of the housing
Often the source of annoying noise is not the unit itself, but improper installation or interaction of the housing with surrounding objects. Resonance is a physical phenomenon in which the vibration frequency the compressor coincides with the natural frequency of vibration of objects, which leads to a multiple amplification of the sound.
The first thing you need to check is the installation level of the refrigerator. If the legs are not adjusted and the housing is skewed, the compressor becomes skewed, which leads to increased vibration. Also, the refrigerator should not touch walls, furniture or curtains. Even a light touch can turn a quiet hum into a loud rattling sound.
Internal components can also become a source of noise. They can rattle:
- 🔧 Shelves and drawers: if they do not fit tightly in the grooves.
- 🔧 Bottles and dishes: standing close to each other on the door.
- 🔧 Egg trays: often vibrate from the operation of the motor.
Particular attention should be paid to the rear grille (condenser). If it is not fastened tightly or is deformed, it will vibrate in response to the operation of the compressor. Sometimes it is enough just to straighten the pipes or place a piece of rubber under the grille to eliminate the noise.
⚠️ Attention: Do not move the refrigerator close to the wall. For normal operation of the cooling system and reduction of resonance, a gap of at least 5-10 cm is required from the back wall to the furniture.
No Frost system: specific defrosting sounds
Refrigerators with the system No Frost have a more complex design, including fans and defrost heaters. This makes adjustments to the sound profile of the device. One of the characteristic sounds is the operation of the fan, which drives cold air through the chambers.
If you hear a howling or humming sound that increases when the door is opened (when the fan can change operating mode), this may indicate icing of the blades or wear of the fan bearing. In some cases, the blades touch frozen ice, creating a cracking sound.
Cyclic crackling and clicking noises in No Frost models are often associated with the automatic defrosting system. The plastic of the fan box and the metal elements of the evaporator expand and contract with temperature changes, producing sounds similar to gunshots or crackling sounds. This is absolutely normal for this technology.
Also, in the No Frost system, the sound of dripping water is often heard. This melts the ice from the evaporator during the defrost cycle and drains into the drain pan above the compressor. If the drain is clogged, water can drip directly onto the hot compressor, causing hissing.
Why does the fan make more noise in winter?
In winter, when the humidity in the room is lower, ice in the No Frost system can build up unevenly, creating an imbalance in the blades and increasing rotational noise.
Diagnostics of faults by the nature of the sound
Experienced technicians can determine the type of breakdown simply by listening to the refrigerator. Different types of faults give rise to unique acoustic signatures. For example, a loud bang when turned on may indicate a problem with the start relay, and a continuous loud hum may indicate that the compressor is running “idle” due to a freon leak.
Below is a table that helps classify sounds and their probable causes:
| Sound type | Probable cause | Urgency of repair |
|---|---|---|
| Uniform quiet hum | Normal operation of the compressor | Not required |
| Loud gurgling | Freon circulation (normal) or leakage | Observation |
| Metal clanging | Destruction of the compressor suspension | High |
| High-pitched whistle | Refrigerant leakage through a microcrack | High |
| Crackling and clicking (cyclic) | No Frost defrosting system (norm) | Not required |
It is important to note that start relay also makes sounds. When the engine starts, a clicking sound is heard, and when the engine stops, a clicking sound is heard. If the clicking sounds become very frequent (every few seconds) and the refrigerator does not start, this is a sign of a faulty relay or a jammed compressor.
Another source of sound is the capillary tube. If it vibrates and touches other tubes or the housing, a high-frequency ringing occurs. By carefully bending the tube with your hand (only when the refrigerator is turned off!), you can temporarily test this hypothesis.
☑️ Noise diagnostics
When noise becomes a problem: critical signs
There is a fine line between operating vibration and a harbinger of failure. If you notice that the nature of the sound has changed sharply and suddenly, this is a reason to be wary. New sounds always indicate a change in the operation of the mechanical or thermodynamic systems of the device.
A dangerous signal is a situation when the refrigerator hums louder than usual, but does not get cold. This means that the compressor is working overload, trying to compensate for the lack of refrigerant or low compression. In this mode, it can burn out in a matter of hours.
It is also worth paying attention to the heating of the compressor housing. If it hums and at the same time heats up to temperatures dangerous to touch, this may indicate an interturn short circuit of the windings or jamming of the compression mechanism.
⚠️ Attention: If you smell the smell of burnt wiring or plastic along with increased noise, immediately unplug the cord from the outlet. Continued operation may lead to a fire.
Sometimes the problem lies not in the refrigerator itself, but in the electrical network. Voltage surges can cause humming noise from transformers or unstable motor operation. Using a voltage stabilizer can solve the problem if the cause lies in poor quality power supply.
Understanding how the refrigerator works and what sounds it makes normally will allow you not to panic over trifles and notice a real threat in time. Regularly checking the installation level and the cleanliness of the condenser grid are the best ways to ensure quiet and long-term operation of your equipment.
Why does a refrigerator make a “ticking bomb” sound?
A sound resembling ticking or rare clicks most often comes from the thermostat. This is normal: when the temperature in the chamber reaches the set value, the contacts open (click) and the compressor turns off. When the chamber heats up, the contacts close again (click), starting the cycle again. If the clicks are very loud, perhaps the thermostat needs to be replaced or its fastening is loose.
Can an old refrigerator be quieter than a new one?
Paradoxically, but yes. Old Soviet refrigerators often ran quieter than modern budget models, as they used more massive and heavier compressors with better sound insulation of the casing. Modern lightweight models can be noisier due to savings on body materials and the use of less vibration-resistant designs, although inverter technologies are designed to correct this.
What to do if the refrigerator hums only at night?
At night, the overall noise level in the apartment drops, and the operation of the refrigerator becomes more noticeable. However, if the humming gets louder at night, check the voltage. At night, the load on the power grid drops and the voltage can rise, causing the compressor to work harder and noisier. Also check if the refrigerator is on an empty shelf or podium that resonates in the silence of the night.
How to reduce the noise of an old refrigerator with your own hands?
You can try replacing the standard legs with anti-vibration stands made of thick rubber. It is also effective to glue vibration-insulating material (bitoplast) to the inner surface of the rear metal wall (only outside the compressor!). Make sure that all shipping bolts (if any) are removed and the compressor does not touch the tubes.