Many users perceive household refrigerator as a given, without thinking about the complex physical processes that occur inside its metal case every day. However, understanding why a refrigerator freezes can significantly extend the life of the equipment and help avoid common mistakes during operation. The operation is based on a continuous cycle of converting the refrigerant from liquid to gaseous and back, which allows heat to be removed from the chambers to the outside.
Unlike simple cooling systems, modern units use complex circulation patterns, including several circuits and electronic sensors. It is the precise interaction of mechanical and electrical components that creates an environment in which food remains fresh for weeks. Let's look at this process in detail so that you can better understand the state of your equipment.
The key element here is the refrigerant - a substance with a low boiling point that circulates in a closed circuit. Freon or its modern analogues, passing through a system of tubes, take thermal energy from the products and release it into the environment through a radiator on the back wall. This process requires constant consumption of electricity to operate the compressor, which creates the necessary pressure in the system.
The principle of the compressor and the creation of pressure
The heart of any refrigeration unit is the compressor, which is often called a motor. It is due to its operation that the pressure difference necessary for the circulation of refrigerant through the system is created. When you hear a characteristic hum or vibration, this means that the compressor compresses freon gas, increasing its temperature and pressure, after which it sends the hot gas to the condenser.
Modern models can be equipped with compressors, each of which has its own operating characteristics. Inverter models operate almost silently and do not turn off completely, but only slow down revolutions, while the classic ones start jerkily. Understanding the type of engine you have will help determine whether it is operating normally and the level of noise it produces.
It is important to note that compression efficiency directly affects the cooling rate of the chambers. If the compressor wears out or there is a freon leak in the system, the pressure drops and the refrigerator stops freezing properly. In such cases, the equipment can work continuously, trying to achieve the set parameters, which leads to overheating and breakdown.
⚠️ Attention: If the compressor works without breaks for days, and the temperature in the chambers does not drop below +10°C, this indicates a loss of tightness of the circuit or a malfunction of the thermostat. Do not try to repair the pressure system yourself without special equipment.
Why is the compressor hot?
When gas is compressed, a large amount of thermal energy is released. The normal temperature of the housing of a working compressor can reach 60-80 degrees Celsius. However, if it is hot to such an extent that it is painful to touch, or, conversely, remains icy when the engine is running, this is a sign of a malfunction.
The role of the condenser and evaporator in heat exchange
After leaving the compressor, the hot gaseous refrigerant enters the condenser. This is the same black lattice radiator that is usually located on the back wall of the refrigerator or built into the side panels. A critically important process occurs here: the gas cools down and turns into a liquid state, releasing the accumulated heat to the air in the room.
Next, the liquid passes through a filter drier and a capillary tube, where the pressure drops sharply. When the refrigerant enters the evaporator located inside the freezer or refrigerator, it boils at a very low temperature. It is at this moment that active absorption of heat from the internal volume of the chambers occurs, which creates a cooling effect.
The evaporator can be of an open type (visible plates in the freezer of old models) or hidden (in the walls of modern units with the system No Frost). The heat transfer area of these elements is designed by engineers to ensure maximum efficiency with minimal energy consumption. Contamination of the condenser with dust or animal hair can upset this balance.
Heat transfer efficiency depends on many factors, including room temperature and chamber loading density. If there is no air circulation around the condenser, the refrigerator will freeze worse. Therefore, it is not recommended to move the equipment close to the wall or cover the ventilation holes with decorative panels.
Refrigerant circulation and phase transitions
The physical basis of the refrigerator’s operation is based on the property of liquids to absorb heat during evaporation. The refrigerant passing through the capillary tube is throttled and its pressure drops. In the evaporator, it begins to actively boil, even at very low temperatures, taking energy from the walls of the chamber and the products.
After the evaporator, gaseous freon again enters the compressor, and the cycle repeats. This process is continuous and regulated automatically. It is important to understand that refrigerant is not used up and does not run out like gasoline in a car. If no mechanical damage has occurred in the system, the amount of freon remains constant for years.
In systems with two compressors or dual-circuit cooling, circulation occurs independently for the refrigerator and freezer compartments. This allows you to set different temperature conditions without mutual influence. In simpler systems with one circuit, the cold is distributed due to convection or fans.
Impaired circulation is often associated with the formation of an ice plug in the capillary tube or clogging of the filter-drier with oxidation products. In such cases, the refrigerant cannot move freely through the circuit, and cooling stops, although the compressor continues to hum.
Temperature control systems and thermostats
The control system is responsible for maintaining the set temperature. In classic models, this function is performed by a mechanical thermostat, which opens the electrical circuit when a certain temperature is reached. More modern units use electronic sensors and control modules that provide high accuracy.
The thermostat or temperature sensor constantly reads the readings inside the chambers. When the temperature rises above the set threshold, the controller gives a command to turn on the compressor. After cooling to the lower limit, the cycle stops. This cyclical operation is typical for most household models.
Electronic systems allow you to implement additional functions, such as super freezing or vacation mode. They can also diagnose faults and display error codes on the display. If the temperature sensor fails, the refrigerator may either not turn on at all or work without stopping, freezing the entire contents.
| Component | Function | Location | Signs of malfunction |
|---|---|---|---|
| Compressor | Gas compression and circulation | Bottom rear | Humming, does not start, overheating |
| Condenser | Cooling and condensation gas | Rear wall | Hot, but does not cool, cold |
| Evaporator | Freon boiling and heat extraction | Inside the chambers | Ice, no cold |
| Thermostat | Adjusting the motor on | Inside the chamber/rear | Does not turn off the motor or does not turn on |
Features of the system No Frost
Technology No Frost (Without frost) has radically changed the approach to food cooling. In such refrigerators, the evaporator is hidden in the back wall of the freezer, and cold air is circulated forcibly using a fan. This avoids the formation of an ice crust on food and walls.
The key difference is the presence of an automatic defrosting system. Periodically, according to a timer, the heating element (heating element) is turned on, which melts the ice that has formed on the hidden evaporator. The water flows into a special tray and evaporates naturally. The user does not need to defrost the refrigerator manually.
However, this system has its own characteristics. A flow of dry, cold air can dry out food faster, so it is recommended to store it in containers or film. In addition, the system requires proper operation of the drainage channels, otherwise water may flow into the chambers or under the refrigerator.
⚠️ Attention: In No Frost systems, it is strictly forbidden to pick the ice with a knife or sharp objects. Damage to the plastic evaporator box or fan will lead to expensive repairs and loss of tightness.
☑️ Diagnosis of cooling problems
The influence of external factors on cooling efficiency
The efficiency of a refrigerator greatly depends on environmental conditions. The temperature in the room where the equipment is located should not exceed the limits specified in the instructions (usually up to +32...+35°C). In hot climates, the compressor will work with increased load, which can lead to premature wear.
Direct sunlight, heat from a stove or radiator also negatively affect the heat transfer process. The condenser should give off heat freely, and if it is hot around it, the refrigerator will stop freezing. The optimal distance from the wall to the rear panel is at least 5-7 cm.
Frequently opening doors or placing hot foods inside causes the system to work in extreme mode. Moisture contained in the air quickly turns into ice on the evaporator, which reduces the efficiency of heat transfer and increases the intervals between cooling cycles.
Voltage stability in the electrical network also plays a role. Voltage surges can damage the compressor start relay or electronics. To protect expensive equipment in conditions of unstable power supply, it is recommended to use stabilizers or surge protectors.
Common reasons for decreased cooling performance
If you notice that the refrigerator freezes less than usual, there may be several reasons. The most common one is a violation of the tightness of the door seal. Over time, rubber dries out, cracks or becomes dirty, allowing warm air to enter. This causes the compressor to work almost non-stop.
Another common problem is a refrigerant leak. Even a microscopic hole in the circuit will eventually lead to the complete disappearance of freon. Symptoms are a condenser that is only a third or half hot, a quiet compressor (if it starts at all) and no cold.
A clogged capillary tube or filter drier also impairs circulation. This may occur due to moisture entering the system or oil breakdown products. In such cases, professional cleaning of the system and replacement of the filter is required, which is only possible in a service center.
Why is it warm in the refrigerator compartment and ice in the freezer?
Often this situation occurs in single-compressor models with a system No Frost. If the channel supplying cold air from the freezer to the refrigerator compartment is clogged or the damper regulator is faulty, the cold simply does not enter the upper chamber. The cause may also be a malfunction of the fan.
Can the refrigerator be used at temperatures below +10°C?
Most refrigerators of the SN-N climate class are not designed to operate in unheated rooms in winter. At low temperatures, the oil in the compressor thickens and the freon may not evaporate correctly, leading to breakdown. There are models of class T or ST, but they need to be specified in the passport.
How often do you need to defrost the refrigerator?
Models with manual defrosting require shutdown approximately once every 3-6 months, when the ice layer reaches 5 mm. Systems Drop (crying wall) in the refrigeration chamber defrost themselves every time the compressor is turned off, and the freezer in them rarely needs to be defrosted. No Frost theoretically does not require defrosting, but preventative washing once a year is useful.
Why are the walls of the refrigerator on the outside hot?
This is a normal workflow. The side walls of modern models often serve as a capacitor. Through them, heat exchange occurs with the environment. If the walls are warm or even hot (up to 50-60°C) while the motor is running, this is normal operation and not a malfunction.