The situation when extraneous sounds arise in turned off refrigerator the owner often confuses and causes anxiety. It would seem that if the compressor is not working and the unit is disconnected from the network, silence should reign inside. However, the physical processes inside the system do not stop instantly, and many of them are accompanied by characteristic acoustic effects.
Hissing, gurgling or whistling can be either an absolutely natural consequence of pressure redistribution in the tubes or a sign of a serious problem. Understanding the nature of these sounds will help you distinguish the normal operation of residual mechanisms from a critical breakdown that requires the intervention of a technician. depressurization of the circuit. Understanding the nature of these sounds will help you distinguish the normal operation of residual mechanisms from a critical breakdown that requires the intervention of a technician.
In this article we will analyze in detail the physics of the processes occurring in refrigerator compartment after a shutdown and identify the real causes of the noise. You will learn why it is important to pay attention to the accompanying signs and how to correctly diagnose the condition of the equipment.
⚠️ Attention: If the hissing is accompanied by a strong smell of gas or you feel a leak, immediately ventilate the room and do not turn on electrical appliances to avoid sparks.
Physics of the process: residual pressure and refrigerant
The main cause of sounds in a switched-off unit is freon (refrigerant), which continues to circulate or change its state of aggregation even after the compressor has stopped. At the moment of shutdown, a significant pressure difference remains in the system between the high and low pressure zones.
Gas tends to equalize this difference by passing through the capillary tube and throttle device. It is this process that is often accompanied by a quiet hissing or whistling sound. This phenomenon is especially typical for models with inverter compressors or a complex heat removal system.
In addition, the liquid refrigerant remaining in the evaporator begins to actively boil as the temperature rises, which also generates characteristic sounds. If the refrigerator was turned off recently, such manifestations are considered the norm and usually last no more than 10-15 minutes.
It is important to consider that that the speed of these processes depends on the ambient temperature and the amount of refrigerant in the system. If the sound changes to a loud whistle and does not stop for a long time, this may indicate that the pressure is being released through a microcrack.
Natural causes: defrosting and thermal expansion
Hissing is not always associated with gas. When the refrigerator is turned off, the process of defrosting accumulated ice and frost begins. Melt water, flowing down drainage channels or dripping onto metal elements, can create sounds reminiscent of hissing or quiet boiling.
It is also worth considering the effect thermal expansion. The plastic elements of the internal lining, shelves and metal tubes of the evaporator compress or expand when the temperature changes. This movement of materials is often accompanied by crackling, clicking and short hissing sounds.
Why does plastic crack?
Plastic and metal have different coefficients of thermal expansion. When suddenly heated after the refrigerator is turned off, the materials deform at different rates, creating acoustic noise.
Such sounds are especially often observed in models with a system No Frost, where there are a lot of plastic air ducts and dampers. If you hear a hissing sound that appears and disappears, most likely, this is simply the design of the device “living.”
- ❄️ Melting ice in the drainage system creates gurgling and hissing sounds as water drains.
- 🌡️ Heating of the metal tubes of the evaporator causes expansion of the metal and a characteristic crackling.
- 💨 The movement of air masses inside the chambers when the temperature changes can imitate wind noise.
- 🧊 Thawing of products with a high water content also contributes to the overall sound background.
Alarm signals: refrigerant leak
Most a serious cause of hissing when turned off is refrigerant leak. If a crack or fistula has formed in the circuit, gas under residual pressure begins to escape. Unlike standard pressure equalization, this process can last for hours.
Often a leak is accompanied not only by sound, but also by other signs. Carefully inspect the interior walls of the chamber and the rear grille. If you notice oily spots or traces of lubricant, this is a sure sign that compressor oil is coming out along with the gas. Attention: Freon itself may have no odor, but the oil circulating in the system has a specific technical aroma. The appearance of a burning or chemical smell is a reason for urgent diagnosis. compressor oil.
⚠️ Attention: Freon itself may have no odor, but the oil circulating in the system has a specific technical aroma. The appearance of a burning or chemical smell is a reason for urgent diagnosis.
It can be difficult to determine a leak by ear, since the sound can be very quiet. However, if the hissing intensifies when you press on certain parts of the tubes or the position of the unit changes, the likelihood of depressurization is high.
If the refrigerator stops freezing after you heard a long whistle, and the compressor works without stopping (or does not turn on at all), then the diagnosis is almost obvious - is broken tightness the system.
The influence of the No Frost system and drainage
In refrigerators with the system No Frost there are more mechanisms that can make sounds. There are fans, defrosting heating elements and complex air duct systems. Even when turned off, residual moisture in the drain pan can react with system elements.
A clogged drain hole often causes water to accumulate and slowly evaporate or flow over, creating sound effects. When melting, an ice plug in the water drainage channel can produce sounds similar to hissing or whistling air.
| System element | Nature of sound | Probable cause | Danger |
|---|---|---|---|
| Evaporator | Quiet hissing, gurgling | Boiling of freon residues | Low |
| Drain channel | Gurgling, squelching | Draining of melt water | Low |
| Circuit tubes | Whistling, hissing | Gas escape through a crack | High |
| Plastic case | Crackling, clicking | Thermal expansion | None |
Checking drainage is the first thing to do before calling the master. It is enough to defrost the refrigerator completely (within 24 hours) and check whether the water flows into the special hole on the back wall.
Diagnostics: how to distinguish normal from breakdown
To understand whether you need to worry, carry out simple diagnostics. First of all, evaluate the duration of the sound. A short hissing (up to 15 minutes) after switching off is normal situation. A long, incessant whistle requires attention.
The second criterion is the efficiency of operation before shutdown. If the refrigerator froze normally, there was no ice on the walls and no foreign odors, then the likelihood of serious damage is reduced. If the equipment has already behaved strangely, hissing may be the final symptom.
☑️ Primary diagnosis of noise
It is also worth paying attention to the behavior of the compressor when turned on (if you decide to turn on the unit again). If it starts with difficulty, hums, but does not cool, and the hissing continues - these are signs compressor malfunction or lack of freon.
Use a soap solution to check suspicious areas if you have visually found a potential leak. Apply foam to the tube connections (accessible without disassembling) and watch for the appearance of bubbles.
⚠️ Attention: Do not use open flames (lighters, candles) to search for freon leaks! This can lead to an explosion or fire, since many refrigerants are flammable.
When you need to call a technician
Independent repair of refrigerators associated with a sealed circuit is practically impossible without special equipment. If you have diagnosed a leak, you will need sealing the crackevacuating the system and charging with new refrigerant.
A call to a specialist is required if:
- 🛠️ You find obvious oil stains on the tubes or inside the chamber.
- 👃 There is a persistent chemical smell or the smell of burnt insulation.
- 📉 The refrigerator stopped gaining temperature after defrosting.
- 🔊 The hissing turns into a loud whistle and does not stop for days.
Attempts to seal the tubes with ordinary glue or sealant will not yield results, since the pressure in the system and the properties of the materials require professional soldering and specific consumables.
Is it possible to use a refrigerator with a leak?
It is impossible to operate such a refrigerator. The compressor will work hard, trying to compensate for the lack of cold, which will lead to its combustion. In addition, the products will spoil.
Prevention and proper care
To minimize the risks of problems with tightness and sound comfort, it is important to properly care for the equipment. Regular defrosting (even for the system No Frost once a year) helps keep the drainage clean.
Avoid sudden temperature changes when washing the refrigerator. Do not pour hot water on cold shelves and walls - this causes microcracks in the plastic and deformation of metal elements, which can lead to noise in the future.
Watch the position of the unit. If the refrigerator is not level, vibrations during compressor operation (until the moment it is turned off) can weaken the fastenings of the tubes, which will eventually lead to their breakage or cracks.
Why does the refrigerator hiss immediately after defrosting?
After defrosting, a lot of moisture remains in the system, which begins to actively evaporate when turned on for the first time. There is also a sharp change in pressure in the circuit. This usually goes away within an hour of operation.
Is the hissing of freon dangerous to health?
Modern refrigerants (R600a, R134a) in low concentrations, which can be released during a microcrack, are not toxic to humans. However, R600a (isobutane) is explosive if accumulated in a confined space, so ventilation is necessary.
Can a new refrigerator hiss?
Yes, new models can “make noise” when setting the temperature settings for the first time. The refrigerant actively moves through the tubes and the pressure is adjusted. If the sound is not accompanied by a burning smell, this is normal.
What to do if the hissing does not stop for several days?
If the sound continues for more than 24 hours after turning it off or on, this is almost guaranteed to indicate a leak. It is necessary to disconnect the device from the network and call a technician to look for the fistula.
Does the temperature in the room affect hissing?
Yes, in a hot room the processes of refrigerant boiling and ice melting are more intense, which can enhance the acoustic effects. Also in summer, the compressor works longer, and residual effects after shutdown may be more pronounced.