The question of what exactly makes the refrigerator cold seems simple only at first glance. For most users, it's just a white cabinet that somehow magically keeps food fresh. However, behind this everyday comfort lies a complex physical processbased on the laws of thermodynamics and the constant movement of substances.
The refrigerator compartment does not produce cold in the usual sense of the word, like, for example, ice in the freezer. Instead, it removes heat from the internal volume and transfers it out into the environment. Understanding this principle is critical for proper operation and fault diagnosis.
In this article we will examine in detail which units and components are responsible for creating low temperatures. You will learn why, without a compressor, refrigerant, and proper heat exchange, the system will stop working, and what happens inside the circuit every second.
Physical principle: heat absorption
To understand what makes a unit cool, you need to understand the basic law of physics: cold is not matter or energy that can be “added.” Cold is just lack of heat. The operation of a refrigerator is based on the ability of a liquid to actively absorb thermal energy from the environment during evaporation.
A special substance circulates inside the system - refrigerant. In a certain section of the circuit, called the evaporator, the pressure drops sharply. This causes the liquid to boil at very low temperatures, instantly turning into a gas. It is at this moment that active heat absorption occurs active heat absorption from the food and air inside the chamber.
⚠️ Attempts to speed up cooling by setting the temperature on the thermostat too low will not increase the freezing rate, but will lead to overload of the compressor and increased consumption electricity.
Gas, saturated with heat, is removed from the evaporator and compressed, after which it releases the accumulated energy through the radiator on the rear wall. This cyclic process creates the necessary microclimate for food storage.
The role of the compressor: the heart of the system
The main engine of the entire process is the compressor. This is an electromechanical pump that creates a pressure difference in the system, forcing the refrigerant to move in a closed circuit. Without this unit, the circulation of the substance is impossible, and heat exchange stops.
The compressor sucks in low-pressure gaseous refrigerant from the evaporator and compresses it. When compressed, the gas is heated and sent under high pressure to the condenser. Modern models can be equipped with inverter motorsthat operate smoothly, unlike older linear analogs that turn on at full power.
If you hear a characteristic hum or vibration emanating from the rear lower part of the case, then the “heart” of the system is working. However, silence when the light is on and the fan is running often indicates a breakdown of the start relay or the motor windings.
Refrigerant: working fluid of the cycle
The substance that is directly responsible for the transfer of thermal energy is called refrigerant or freon. For a long time, chlorine-based compounds were used, but due to their harm to the environment, the industry switched to safer mixtures, such as R600a (isobutane) or R134a.
These gases have a unique property: they are able to change their state of aggregation (from liquid to gas and back) at temperatures available for domestic use. The amount of refrigerant in the system is strictly regulated by the manufacturer.
If even a microscopic leak occurs in the circuit, the cooling efficiency drops. The compressor starts working non-stop, trying to compensate for the lack of working fluid, but the temperature in the chambers does not drop to the required values.
Why can’t you refuel the refrigerator yourself?
Refilling requires not only gas, but also evacuation of the system. The remaining moisture or air in the circuit will lead to the formation of an ice plug and failure of the compressor in a short time.
Condenser and capillary tube
After compression in the compressor, the hot gas enters the condenser. This is a lattice radiator, usually located on the rear wall or built into the side panels. This is where heat transfer occurs heat transfer into the atmosphere of the kitchen.
Passing along a long condenser coil, the gas gradually cools and turns into a liquid state. The flow then enters the capillary tube. This is a very narrow channel that serves as a throttle - it sharply reduces the pressure before entering the evaporator.
It is at the exit from the capillary tube, where the pressure drops, that the refrigerant boils. If the capillary becomes clogged with oil breakdown products or moisture, circulation is disrupted and the refrigerator stops cooling, although the compressor may hum.
Evaporator: where the cold is born
The evaporator is the very unit that directly cools the internal volume of the chamber. Depending on the defrosting system, it can be hidden behind a plastic panel (in the system No Frost) or be an open coil with shelves (in drip systems).
The air from the chamber is forced or naturally circulates around the cold evaporator tubes, giving off its heat to the refrigerant. In models with no frost, this process is monitored by a fan, which drives air through the evaporator and distributes it through the channels.
Frost or ice always forms on the surface of the evaporator, since moisture from the air of the products condenses on the cold walls. Periodic defrosting (automatic or manual) is necessary to remove this ice crust, which works as heat insulator and interferes with effective cooling.
Thermostat and control sensors
To prevent the refrigerator from turning food into ice monolith, a control element is needed. In classic models, this role is played by a thermostat - a mechanical device with a bellows that responds to changes in temperature.
When the air in the chamber cools, the gas in the bellows is compressed, the contacts open, and the compressor turns off. As the temperature rises, the process repeats. Modern digital models use electronic sensorswhich transmit data to the control module.
Thermostat malfunction is a common cause of problems. If it is “stuck” in the “on” position, the refrigerator will freeze until it stops. If the contacts do not close, the equipment simply will not start and the products will deteriorate.
Below is a table describing the main components and their effect on the cooling process:
| Component | Function | Symptom malfunction |
|---|---|---|
| Compressor | Creates pressure, drives freon | Does not turn on, hums, but does not start |
| Refrigerant | Transfers heat | Leakage, lack of cold when the engine is running |
| Condenser | Gives heat to the room | Hot bottom, cold top (or vice versa) |
| Thermostat | Regulates operating cycles | Does not turn off or does not turn on at all |
☑️ Symptoms that require calling a technician
Heat removal and ventilation systems
The efficiency of a refrigerator directly depends on how well it transfers heat. This requires free air circulation around the housing. Many users make the mistake of building equipment into a niche without gaps or moving it close to the wall.
If the heat cannot escape into the kitchen atmosphere, it remains inside the system. The pressure in the condenser increases, the compressor works at the limit of its capabilities, trying to push the refrigerant, but heat exchange it is broken. This leads to overheating and emergency shutdown.
Ventilation inside the chamber also plays an important role, especially in No Frostsystems. Clogged air ducts or a faulty damper can lead to ice in the freezer and heat in the refrigerator compartment, although the unit is working properly.
⚠️ Attention: The distance from the back wall of the refrigerator to the wall or furniture must be at least 5-7 cm to ensure normal air convection.
The influence of external factors on cold
A refrigerator is not an isolated system, it depends on environmental conditions. Room temperature, direct sunlight, proximity to heating devices - all this affects how quickly and efficiently it will cool.
In a hot room, the temperature difference between the condenser and the air decreases, which reduces the efficiency of heat transfer. The compressor has to work longer to reach the set parameters. In winter, on the contrary, if the refrigerator is placed on an unheated veranda, the oil in the compressor may thicken.
Frequent opening of doors also makes its own adjustments. Warm, moist air enters the chamber and needs to be cooled and dried. This increases the load on the evaporator and requires more time to restore the temperature.
Diagnostics: why the cold disappeared
If you notice that food has begun to deteriorate faster, and there is no frost on the walls (or, conversely, a “fur coat” has formed), which means there is a failure in the system. Primary diagnostics helps to understand why exactly the unit stopped cooling.
Check whether the light is on and whether the fan is working. Place your hand on the side walls - they should be slightly warm. If the housing is cold but warm inside, there may be a freon leak or a clogged capillary tube.
If the compressor runs non-stop and there is no cold, this may indicate a loss of tightness in the circuit or a loose door seal. In this case, the cold simply “evaporates” out faster than it is created.
Why does the refrigerator freeze but does not turn off?
Most often this indicates a refrigerant leak. The compressor tries to compensate for the lack of gas by constantly working, but cannot reach the required pressure to stop the thermostat. Also, the reason may be a worn door seal or a breakdown of the thermostat itself.
Is it possible to use a refrigerator at temperatures below +10°C?
Most manufacturers do not recommend operating equipment at temperatures below +10°C (for example, on a balcony in winter). The oil in the compressor thickens, lubrication deteriorates, which leads to rapid wear of parts. In addition, problems may arise with defrosting the evaporator.
What to do if it is warm in the refrigerator compartment, but normal in the freezer?
This is a classic sign of a malfunction of the No Frost system (the air supply channel is frozen or the fan is broken) or a freon leak (if the model is dual-circuit). It is also worth checking the air flow control damper.