A modern refrigerator is a complex unit where each element plays a critical role in maintaining food freshness. Many owners of household appliances come across the term “circuit” in instructions or when talking with a technician, but do not fully understand its physical essence.
In fact, in the design of a cooling device there are several closed systems, which are often called circuits. This may be refrigeration circuitthrough which freon circulates, or defrost circuitpreventing the formation of an ice crust. Understanding their purpose helps to quickly diagnose breakdowns.
In this article we will analyze in detail what circuits are present in your refrigerator, how they interact with each other and why failure of one of them leads to failure of the whole system.
Main refrigeration circuit and its purpose
The main task of any refrigeration unit is to remove heat from the inner chamber to the outside. The main refrigeration circuit, which is a closed system of tubes, is responsible for this process. It is within this circuit that there is continuous circulation of the refrigerant (freon), which changes its state of aggregation, taking away thermal energy.
Circulation of the substance is impossible without a compressor, which acts as the heart of the system, creating the necessary pressure. Gaseous freon is compressed, heated and sent to the condenser (usually a grille on the back or sides of the housing), where it releases heat into the room and condenses into liquid.
Next, the liquid refrigerant passes through capillary tube or a choke, where the pressure drops sharply, and enters the evaporator. Here freon boils at low temperatures, which ensures cooling of the internal volume of the chamber.
If the main circuit is damaged, the refrigerator stops cooling, since the freon evaporates and the compressor runs in vain. Restoring the tightness requires professional soldering and vacuuming of the system.
⚠️ Attention: An independent attempt to solder the main circuit tubes without a vacuum pump and a pressure gauge station will lead to rapid failure of the compressor due to moisture and air entering the system.
No Frost system and defrost circuit
Owners of equipment with the system No Frost often wonder why ice does not form inside, although moisture does not disappear from the food. A special defrost circuit (or automatic defrosting system) is responsible for the absence of frost. Unlike older models, where ice accumulated on the back wall, here the evaporator is hidden behind a plastic panel.
During operation, moisture settles on the evaporator, turning into frost. Periodically, based on a signal from a timer or electronics, it turns on Defrost heating element. It heats the evaporator, melting the ice. The resulting water flows through the grooves into a special tray above the compressor, where it evaporates naturally.
The most important element here is the defrost sensor and thermal relay. They control the temperature of the evaporator so that the heating element does not overheat and melt the plastic parts of the chamber. If this circuit fails, a “fur coat” builds up in the freezer, and food begins to spoil.
Often users confuse the defrost circuit with the main cooling circuit, but these are two independent electrical circuits working in tandem. A malfunction of one of them disrupts the temperature balance.
Thermal circuit (anti-condensation tube)
One of the most mysterious elements for the average person is the so-called thermal circuitwhich is often called an anti-condensation tube. If you have ever felt the sides of a running refrigerator and felt warmth, then this circuit is working properly. Its main task is to prevent the formation of condensation on the outer surface of the case.
Inside the walls of the refrigerator, along the perimeter of the doorway, there is a tube into which hot freon enters immediately after the compressor. Passing along this path, the gas gives off some of the heat to the walls, preventing them from cooling below the dew point.
Without this element, in humid conditions (high air humidity), drops of water would constantly appear at the ends of the door and around the seal. This would lead to corrosion of the metal, swelling of the chipboard and the appearance of mold.
In modern models Indesit, LG or Atlant engineers often replace the hot circuit with electric heaters or completely abandon them for the sake of energy efficiency, but the principle remains the same - the fight against moisture.
Why do the sides heat up?
The side walls can heat up to 50-60°C during the first hours of operation of a new refrigerator or during intensive loading of food. This is the normal operation of the thermal circuit, which removes excess heat. If only one point heats up or a burning smell is heard, this is a sign of a faulty electrical wiring.
Comparison of circuit types in different systems
Different models of refrigerators use different combinations of the described systems. Understanding which contour is dominant in your model helps you properly care for your equipment. For example, in full systems No Frost the main emphasis is on ventilation and defrosting, and in drip systems - on the correct operation of the main cycle.
Below is a table showing the differences in the operation of circuits depending on the type of cooling system.
| System type | Main circuit | Defrost circuit | Thermal circuit |
|---|---|---|---|
| Static (Drip) | One evaporator per chamber | Natural defrost when the compressor stops | Often present (the sides get hot) |
| No Frost (Refrigerator compartment) | Separate circuit or damper | Heating element + timer + sensor | May be absent (ventilation) |
| No Frost (Freezer) | Open evaporator | Required regular defrosting | Often replaced with electrics |
| Full No Frost | Two independent contour | Automatic for both compartments | Optional |
As can be seen from the table, the complexity of the design directly affects the number of potential points of failure. The more elements in the circuit, the higher the requirements for assembly quality and operating conditions.
Diagnostics of circuit malfunctions
You can determine which circuit has failed using indirect signs. If the refrigerator hums but does not cool, most likely the problem is in the main refrigeration circuit (freon leak or capillary blockage).
If a huge block of ice has formed inside the chamber, and the food in the upper tiers is warm, then it is broken work defrost circuit. Ice blocks the cold air supply channels, and the fan stops effectively moving air through the chamber.
The appearance of water on the floor under the refrigerator or drops on the inner walls near the door often indicates problems with the drainage system or the heating circuit. Water does not have time to evaporate or condensation is not prevented.
For accurate diagnostics, technicians use leak detectors to search for freon leaks and multimeters to check the resistance of heating elements and sensors. A visual inspection is also important: swelling of the back wall or a yellow coating of oil may indicate the location of the breakdown.
☑️ Primary diagnosis of the refrigerator
The influence of operating conditions on service life
The service life of the circuits directly depends on how you use the refrigerator. Frequent opening of the doors disrupts the humidity balance, forcing the system No Frost to work in increased mode, which reduces the life of the defrosting heating element.
Placing the refrigerator close to the wall or in a niche without gaps leads to overheating of the condenser. The compressor is forced to work longer, the pressure in the circuit increases, which can lead to rupture of thin tubes or failure of the motor.
Using aggressive chemicals to wash the internal chambers can damage the plastic elements covering the evaporator or corrode metal parts. It is important to use only recommended products.
⚠️ Attention: Never use sharp objects (knives, screwdrivers) to chip ice in the freezer. One careless movement can pierce the aluminum evaporator, and the main refrigeration circuit will lose its seal instantly.
Repair and restoration of tightness
If a leak is diagnosed in the heating circuit (the sidewalls have stopped heating, condensation has appeared), craftsmen often decide to seal (cut off) this area. For domestic use, this is acceptable, since it does not interfere with the main cooling function, only slightly increasing the risk of condensation in wet weather.
Repairing the main circuit is a labor-intensive process. It includes searching for leaks, soldering (or replacing the section), installing a new filter-drier, vacuuming the system for 30-40 minutes and filling with freon of a strictly defined brand and weight.
Restoring the defrost system usually requires replacing a burnt heating element, timer or sensor. These items are consumables and wear out over time. It is important to select spare parts that correspond to the specific model of the refrigerator.
High-quality repairs can extend the life of the unit by 5-7 years. However, if (corrosion) has affected more than 30% of the evaporator surface, it is often more advisable to consider purchasing new equipment.
Is it possible to operate a refrigerator if the sides do not heat up?
Yes, it is possible. The absence of heating of the side walls only indicates that the thermal (anti-condensation) circuit is not working. This does not affect the cooling process of products. The only negative is the possibility of drops of moisture appearing at the ends of the door in very humid rooms.
Why does the refrigerator take a long time to reach the temperature after defrosting?
After complete defrosting and turning on the network, the refrigerator takes time (from 2 to 6 hours) to reach operating mode. At this time, the refrigerant is circulating in the main circuit, but has not yet reached the required concentration and pressure for effective cooling of the entire volume.
Is the appearance of oil around the tubes at the back of the refrigerator dangerous?
Yes, this is a dangerous symptom. The oil in the refrigeration circuit circulates along with freon to lubricate the compressor. If you see oil stains on the pipes or at the base of the compressor, it means that the system has become depressurized and there is a refrigerant leak. You cannot operate such a refrigerator.
How often do you need to defrost a refrigerator with the No Frost system?
Technically, the system No Frost does not require manual defrosting to remove ice, as it does it automatically. However, manufacturers recommend turning off the device once every 6-12 months for general cleaning, disinfection and checking the drainage holes for blockages.