Many owners of household appliances are faced with a situation where, after turning off the compressor the refrigerator makes loud cracking sounds. This effect is often called decompression, although technically the process describes the equalization of pressure in a closed system. For most users, this phenomenon seems like an alarming signal of a breakdown, but in 80% of cases it is an absolutely normal physical process.
Sudden temperature changes and changes in refrigerant pressure inside the circuit cause the metal tubes to expand and contract. It is this movement that generates the characteristic sound, which can be quite strong. Understanding the nature of the occurrence of these noises will help you distinguish the normal operation of the unit from a real malfunction that requires specialist intervention.
In this article we will analyze in detail the physics of the decompression process, consider the causes of extraneous noise and determine the limits of the norm. You will learn to independently diagnose the condition of your unit unit and understand when it is really necessary to sound the alarm.
Physics of the process: why clicks occur
The main cause of sounds during so-called decompression is work thermodynamic system refrigeration chamber. A refrigerant circulates inside the circuit, constantly changing its state of aggregation from liquid to gaseous and back. When the compressor turns off, the pressure in the system begins to equalize, and the temperature of the evaporator and condenser tubes drops sharply.
The metal from which the pipelines and heat exchangers are made tends to shrink when cooling. Since the tubes are rigidly fixed in the housing or foamed in thermal insulation, mechanical stress occurs during sudden compression. At the moment when the frictional force is overcome, an instant displacement of the metal occurs, which we hear as a loud click or crack.
⚠️ Attention: If the crack is accompanied by vibration of the housing or a hum that does not stop for more than 5 minutes after stopping the motor, this may indicate a violation of the fastening of the internal elements.
The intensity of the sounds directly depends on the temperature difference and cooling rate of the circuit. Modern models with the system No Frost can make more frequent clicks due to the presence of additional plastic elements and fans that also react to temperature changes.
Normal or pathology: how to distinguish safe noise
It is important to be able to differentiate natural decompression sounds from signs of malfunction. A sound background that occurs exclusively when the compressor stops or immediately after it starts is considered normal. These sounds are usually single or serial, but short-lived.
If you hear continuous hissing, gurgling or frequent clicks throughout the entire operating cycle, this may indicate problems. Extraordinary noise often indicate a freon leak, a clogged capillary tube or a faulty start relay.
Particular attention should be paid to the nature of the sound. Decompression crackling always has a “metallic” tint. If the sound is more like the knocking of wooden parts or the hum of a transformer, the reason lies in another node.
For a more accurate diagnosis, you can use the following table, which will help classify the sounds:
| Sound type | Time of occurrence | Probable reason | Status |
|---|---|---|---|
| Loud click | When the engine is turned off | Metal compression (decompression) | Normal |
| Quiet gurgling | At any time | Refrigerant flow | Normal |
| Frequent crackling | During operation | Frozen fan or ice | Requires inspection |
| Whistling or hissing | Constantly | Freon leakage | Repair |
Influence of design on noise level
The design features of the refrigerator model play a key role in the volume of decompression noises. Units with an open arrangement of the condenser grille (at the rear) usually make less noise, since the tubes have more freedom for thermal expansion.
In models where the entire circuit is foamed in the thermal insulation of the case, the sounds may be muffled, but due to the rigid fixation of the tubes inside the foam, the compression stress may be higher. Thermal insulation in such cases it acts as a resonator, transmitting sound to the entire body.
⚠️ Attention: In new models with inverter compressors, the nature of the noise may differ from classic linear motors due to a smooth change in pressure in the system.
It is also worth considering the material of the shelves and internal plastic panels. During sudden cooling, plastic contracts faster than metal, which generates additional clicks, which users often confuse with circuit decompression.
Why do old refrigerators crack more?
Old models often have less effective thermal insulation and more rigid tube fastenings. In addition, over years of use, the metal may have become “tired” and deformed, which enhances the shape memory effect during heating and cooling cycles.
Diagnostics of refrigerant problems
Although decompression is a normal process, it can sometimes mask more serious circulation problems. refrigerant. If the pressure in the system is disturbed, the nature of the sounds changes. For example, when there is a freon leak, the compressor tries to compensate for the lack of pressure by working longer, and decompression sounds become less frequent, but may be accompanied by hissing.
Clogged capillary tube is another reason for a change in the acoustic profile. In this case, decompression occurs unevenly and you may hear strange sounds like gunshots or pops. This is due to the fact that the gas passes through a narrow cross-section at a high speed.
For an initial check, you can carry out a simple test: put your hand on the side walls of a working refrigerator. They should be warm. If the walls are cold and the motor is humming, but there is no cold, there is probably a leak or (clogging).
Methods for reducing noise levels
If decompression sounds make you uncomfortable, especially at night, there are ways to minimize their impact. It is impossible to completely eliminate the physical process of metal compression, but you can reduce the resonance.
The first thing to do is check the installation of the refrigerator. Vibration from the compressor transmitted to the floor can amplify the sounds of decompression. Make sure that the legs of the refrigerator are adjusted and that it stands stable and does not wobble.
It is also worth checking the distance to the walls. If the refrigerator is close to furniture or a wall, the sound wave is reflected and amplified. Leave a gap of at least 5-10 cm for free circulation of air and sound waves.
☑️ Checking the installation of the refrigerator
In some cases, installing the refrigerator on a special anti-vibration substrate helps. This is especially true for models with a bottom-mounted compressor, where vibration is transmitted directly to the floor.
When you need to call a technician
There are clear criteria under which independent waiting “will go away on its own” is unacceptable. If decompression is accompanied by other alarming symptoms, you should not hesitate. Refrigerator repair may be necessary if the sounds become constant.
Pay attention to the temperature in the chambers. If you hear the usual clicking sounds, but the food has stopped freezing or, conversely, is cooling too much, this is a sign of a failure in the control system or a leak.
⚠️ Attention: Attempts to open the circuit yourself or replace the compressor without special equipment and a license to work with freon are prohibited and dangerous.
A specialist is also needed if the clicks are accompanied by a burning or plastic smell. This may indicate overheating of the starting relay or motor windings, which is a harbinger of a serious breakdown.
Why does the refrigerator crack only at night?
At night, the level of background noise in the apartment decreases, and the human ear becomes more receptive to sounds. In addition, room temperature differences may be smaller at night, which changes the dynamics of heat transfer. It often seems that the refrigerator makes noise only at night, although during the day you simply do not notice these sounds.
Can decompression damage the refrigerator?
The decompression process itself is absolutely safe for equipment. This is a natural physical phenomenon. The unit can only be damaged by ignoring accompanying symptoms, such as a freon leak or a compressor malfunction, which are disguised as ordinary sounds.
Does the volume of clicks depend on the number of products?
Yes, it indirectly depends. A full refrigerator maintains its temperature better, so the compressor turns on less often. Fewer on-off cycles means fewer decompression cycles. An empty refrigerator will “crack” more often due to frequent engine starts.