The desire to turn an ordinary refrigerator into a full-fledged freezer often arises when it is necessary to store large volumes of meat, fish or preparations for the winter. Many owners of household appliances are wondering whether it is possible to artificially lower the temperature in the main chamber to -18°C or lower without buying a separate freezer. Theoretically, this is possible, but in practice such a modification requires deep intervention in the design and control system.
Standard single-compartment refrigerator designed to maintain positive temperatures, usually in the range from +2°C to +8°C. Its insulation, compressor power and evaporator design are not designed to withstand extreme cold. An attempt to force the device to operate in deep-freeze mode will lead to increased load on the engine and may cause its premature failure.
In this article we will look at the technical aspects of such a modification, analyze the physics of the cooling process and evaluate the real risks. You will learn why simply turning the thermostat knob is not enough and what engineering solutions are used to achieve ultra-low temperatures in domestic conditions. It is important to understand that any intervention in the refrigerant system requires qualifications.
Fundamental differences between refrigeration and freezer compartments
To understand the complexity of the task, you need to understand the physics of the refrigeration circuit. The main difference is not only in the set temperature, but also in the thermal insulation case. Freezers have a thicker layer of polyurethane foam, since the difference between the internal temperature (-18°C) and external (+25°C) is more than 40 degrees. In a conventional refrigerator, this difference is much less.
The second critical factor is area and design evaporator. Freezers use a system No Frost or a powerful tubular evaporator that can remove large amounts of heat in a short time. In the refrigerator compartment, the evaporator is often hidden behind the back wall or designed as a coil optimized for gentle cooling rather than blast freezing.
⚠️ Attention: Reducing the temperature in the main chamber below +4°C will cause food in the upper tiers to freeze and be damaged. their structure, and the compressor will work without stopping, which is fraught with overheating of the windings.
It is also worth mentioning the refrigerant. Although both devices may use similar freons (for example, R600a or R134a), the system pressure and boiling point of the refrigerant in the freezer are set differently. Throttling of the flow in the capillary tube is selected for a specific operating temperature.
Mechanical adjustment of the thermostat
The simplest, but least effective way to try to lower the temperature is to adjust the mechanical thermostat. Inside the device there is a bellows that responds to changes in the volume of gas or liquid when the temperature changes. Turning the adjusting screw rod changes the spring tension, shifting the temperature threshold for turning off the compressor.
However, this method has severe limitations. The design of thermostats, such as TAM-133 or K-59, provides an operating range corresponding to the refrigeration chamber. Even with the maximum minus setting, the sensor can turn off the compressor when it reaches -5°C...-8°C, which is not enough for full freezing.
- 🔧 Find the adjusting screw under the plastic thermostat handle (usually requires removing the handle).
- ❄️ Turn the screw clockwise half a turn, waiting 2-3 hours between adjustments.
- 🌡️ Use an external thermometer to monitor the actual temperature inside the chamber.
- ⚠️ Do not unscrew the screw all the way - this may lead to “sticking” contacts or the inability to turn off the compressor.
If your refrigerator is equipped with an electronic control, the situation becomes more complicated. The controller is programmed with factory limits. An attempt to deceive the temperature sensor (thermistor) by adding resistance can lead to a system error and transition to emergency mode.
How does a thermostat work?
There is a gas or liquid inside the sealed capsule. When cooled, they contract, the membrane bends and opens the electrical contacts, turning off the compressor. The adjustment changes the force required for this bend.
The need to strengthen thermal insulation
If you managed to achieve low temperatures, the next step will be to combat heat gain. Standard refrigerator walls 3-4 cm thick will begin to actively freeze, which will lead to the formation of condensation ("dew") on external surfaces and icing of the seals.
For effective operation in freezer mode, it is necessary to increase the insulation layer. This can be done by covering the internal walls (if volume allows) or external surfaces with an additional layer penofol or extruded polystyrene foam. However, this will reduce the useful volume of the chamber.
Particular attention should be paid sealing rubber. At extremely low temperatures, standard rubber becomes tanned and no longer provides a seal. Cold air will go out, and warm air will flow in, forcing the compressor to work continuously.
In some cases, enthusiasts resort to completely replacing the door leaf with a thicker one taken from an old freezer, but this requires complex rehanging of the hinges and adjusting the dimensions.
Replacement refrigerant and capillary tube
This is the most difficult and dangerous stage, requiring professional equipment and skills. Reaching temperatures below -18°C in a system not designed for this often requires changing the refrigerant to a mixture with a lower boiling point or changing the length of the capillary tube. The capillary tube acts as a choke, creating a pressure difference between the condenser (high pressure) and the evaporator (low pressure). The length and diameter of the tube are calculated by engineers for the specific compressor performance and evaporator volume. Changing these parameters will upset the balance of the system. capillary tube.
The capillary tube acts as a throttle, creating a pressure difference between the condenser (high pressure) and the evaporator (low pressure). The length and diameter of the tube are calculated by engineers for the specific compressor performance and evaporator volume. Changing these parameters will upset the balance of the system.
Mineral / AlkylbenzenePolyol Ester (POE)| Parameter | Refrigerator | Freezer | Risk during alteration |
|---|---|---|---|
| Boiling point | -30°C...-35°C | -45°C...-50°C | Insufficient cooling |
| Discharge pressure | Average | High | Circuit rupture |
| Oil in the compressor | Oil incompatibility |
In addition, it is necessary to take into account the compatibility of the oil and refrigerant. Using an unsuitable mixture can lead to coking of the oil passages and jamming of the compressor after a short time.
⚠️ Attention: Replacing freon yourself is prohibited by law in many countries due to environmental regulations. In addition, working with gas under pressure without a license is life-threatening.
Risks for the compressor and service life
The main victim of such modernization is the compressor. Working at the limit of its capabilities or beyond the design regime, it is subjected to colossal overloads. The temperature of the motor windings can reach critical values, which leads to destruction of insulation and interturn short circuit.
In deep freezing mode, the compressor operating time increases to 90-95% of the total time (high switching factor). In normal mode, this figure is about 40-50%. The service life of rubbing parts (piston group) is exhausted 3-4 times faster.
The risk of water hammer is also high. If the liquid refrigerant does not have time to completely evaporate in the evaporator due to changed heat exchange conditions, it will enter the compressor, which can instantly damage it.
Alternative solutions and conclusions
Taking into account all the technical difficulties, risks and costs, converting a refrigerator into a freezer often turns out to be economically impractical. The cost of labor, new materials and potential repairs may exceed the price of a used freezer.
If you still need to store food at low temperatures, consider the following options:
- 🏪 Buying a separate chest freezer or cabinet (the most reliable option).
- 🛠 Installing an external one temperature controller (thermal relay) for precise control of cycles, if the risk of breakdown does not bother you.
- ❄️ Using dry ice in an insulated container inside the refrigerator for temporary storage.
In conclusion, it is worth noting that modern two-chamber refrigerators already have a "Fresh" or "Zero" zone, where the temperature is close to 0°C, but They are not a full-fledged freezer. Engineers created these devices for different tasks, and mixing their functions leads to a compromise in the quality of work.
☑️ Is it worth remodeling?
Frequently asked questions (FAQ)
Is it possible to install a thermostat from a freezer into a refrigerator?
Theoretically, it is possible if the fit dimensions and bellows type match. However, the temperature range of the new thermostat may not correspond to the thermophysical properties of your evaporator, which will lead to incorrect operation or freezing of the melt water drainage channel.
Why does the refrigerator not freeze below -5 degrees?
This limitation is inherent in the design of the evaporator and the power of the compressor. The heat exchange area is insufficient to remove heat at such a temperature delta. An attempt to force the process will only lead to fouling of the evaporator and stopping the air circulation.
Is it dangerous to keep a refrigerator on the balcony in winter for freezing?
Yes, it is dangerous. At temperatures below +10°C, the oil in the compressor thickens, which leads to dry starting and breakdown. In addition, moisture can damage the electrical system. Use the device only in a heated room.
How much electricity will the converted refrigerator consume?
Electricity consumption will increase by 2-3 times. The compressor will work almost without interruption, trying to compensate for heat inflows through insufficiently thick walls.