When household appliances break down or extraneous sounds appear, many owners wonder about the internal structure of the unit. There is often confusion as to what exactly circulates inside the closed circuit and why oil is needed there. Understanding the principles of operation of the refrigeration circuit helps to quickly diagnose a malfunction.
A special substance circulates inside the system, which can easily pass from a liquid to a gaseous state and back. It is this process of evaporation and condensation that allows heat to be removed from the chambers, providing a low temperature for storing food. Without this working environment the refrigerator is just a metal box.
In addition, there is always technical lubricant in the lower part of the motor. It is necessary to reduce friction of moving parts and remove heat from rubbing surfaces. Mixing these two components in certain proportions or their complete loss leads to critical breakdowns that require complex and expensive repairs.
Main substance: refrigerant and its role
The main liquid that provides cooling is refrigerantwhich in everyday life is often called freon. This substance has the unique property of boiling at very low temperatures, even at atmospheric pressure. In a closed loop, the pressure is artificially increased by the compressor, which allows the gas to condense into liquid, releasing heat to the environment through the condenser.
Passing through capillary tube, the pressure drops sharply, and the refrigerant boils in the evaporator, actively absorbing heat from the internal space of the chambers. This cycle is repeated continuously until the thermostat registers that the set temperature has been reached. Modern models can use different brands of gases, each of which has its own physical and chemical properties.
⚠️ Attention: Refrigerants are colorless and odorless, but some of them are heavier than air and can displace oxygen in poorly ventilated areas. If you suspect a leak, you must immediately open the windows and provide fresh air.
It is important to understand that the amount of refrigerant is strictly regulated by the manufacturer. Excess or deficiency of the substance disrupts the thermal balance of the system. Refilling can lead to increased pressure and destruction of tubes, and underfilling can lead to overheating of the motor and insufficient cooling.
Why is the refrigerant called freon?
Term "Freon" is a trade name given by DuPont, but in everyday life it is attached to all types of refrigerants. In fact, there are different classes of substances: chlorofluorocarbons, hydrochlorofluorocarbons and others.
The second important component: compressor oil
Inside the sealed compressor casing, in addition to gaseous or liquid refrigerant, there is always compressor oil. It is not directly involved in heat exchange, but performs the critical function of lubricating the piston group, bearings and other rubbing parts of the electric motor. Without this fluid, the mechanism would quickly fail due to friction and overheating.
A feature of modern refrigeration systems is that the oil is partially dissolved in the refrigerant and circulates with it throughout the entire circuit. For this purpose, special synthetic compounds are used that do not precipitate and do not clog the narrow passages of the capillary tube. Older models with R12 freon used mineral oils that were not suitable for new types of gases.
If a leak occurs in the system, part of the lubricant often leaves along with the gas. Visually This can be seen by greasy spots on the tubes or near the compressor. An attempt to simply add gas without restoring the oil level or replacing the compressor can lead to jamming of the piston group.
- 🛢️ Mineral oil - used in old refrigerators with R12 freon, is highly hygroscopic.
- 💧 Synthetic oil (POE) - used with modern refrigerants, resistant to oxidation and mixing.
- 🔄 Semi-synthetics - an intermediate option found in transitional models of equipment.
When replacing a compressor, the technician always adds fresh oil, since the old one could lose its properties or be contaminated with combustion products of the windings. Viscosity Oils are selected strictly for the specific type of refrigerant and engine model.
Types of refrigerants used
Over the decades of development of the refrigeration industry, the compositions of working fluids have changed several times. This was due to the requirements of environmental safety and energy efficiency. Early models ran on ammonia or R12 freon, which destroyed the planet's ozone layer. Now the market is occupied by safer analogues.
Modern eco-friendly gases, such as R600a (isobutane), have excellent cooling properties, but are flammable. This imposes special requirements on the tightness of the system and the qualifications of the repairmen. Other types, for example R134a, do not burn, but require the use of synthetic oils.
The table below shows the main differences between the popular types of refrigerants used in household appliances:
| Type refrigerant | Chemical name | Environmental friendliness | Features |
|---|---|---|---|
| R12 | Dichlorodifluoromethane | Harmful (ozone depleting) | Used in older models up to the 90s |
| R134a | Tetrafluoroethane | Ozone safe | Requires synthetic oil, does not burn |
| R600a | Isobutane | Eco-friendly | Flammable, requires little substance, quiet operation |
| R407C | Mixture of gases | Safe for ozone | Often used in climate control technology |
The transition to new types of refrigerants has reduced the energy consumption of refrigerators. However repair such systems have become more complex, as they require evacuation and precise filling by weight, and not by pressure.
How to determine a leak of working fluid
You can independently understand that the refrigerant has left the system by indirect signs. First of all, pay attention to the temperature in the chambers. If the food in the freezer begins to thaw, and the main compartment is warm, although the compressor is running continuously, this is a sure sign of a leak. The second sign is the appearance of the evaporator. In models with a “crying” evaporator or a No Frost system, during normal operation the tubes or plate should be evenly covered with frost or condensation. If a “bald spot” (an area without frost) or frosting is visible only at the entrance, it means there is little freon in the system. leakage.
The second sign is the appearance of the evaporator. In models with a “crying” evaporator or a No Frost system, during normal operation the tubes or plate should be evenly covered with frost or condensation. If a “bald spot” (an area without frost) or frost is visible only at the entrance, it means there is not enough freon in the system.
⚠️ Attention: Never try to find a leak with an open flame. Many modern refrigerants (R600a) are explosive when mixed with air, which can lead to a fire.
The appearance of the compressor may also indicate a problem. If it works non-stop and gets very hot (to the point where it hurts to touch), this indicates that it is broken. The motor tries to compensate for the lack of refrigerant by working more intensely, which leads to its overload. heat transfer broken. The motor tries to compensate for the lack of refrigerant by working more intensely, which leads to its overload.
Why you can’t add liquid yourself
Many users mistakenly believe that restoring the functionality of the refrigerator is simply “topping up gas,” similar to refilling the air conditioner in a car. This is a dangerous misconception. The refrigeration circuit is a closed system, and in good condition there should be no leaks. If the gas is gone, it means that a a hole hole has formed in the tube or evaporator.
Simply adding refrigerant without eliminating the cause of the leak is pointless - it will come out again in a few days or weeks. Moreover, the entry of air and moisture into the system during handicraft refueling leads to the formation of acids that corrode the metal from the inside, and blockage of the capillary pipeline with ice plugs.
For quality repairs it is necessary:
- 🔍 Find the leak using a leak detector or soap solution.
- 🔧 Eliminate damage (soldering, replacement of unit).
- 💨 Vacuum the system to remove moisture and air.
- ⚖️ Fill the system strictly according to the weight indicated on the nameplate.
Use cylinders with "universal" Freon substitutes that are sold on the Internet often lead to the final failure of the compressor. Composition Such mixtures are unknown and may be incompatible with the oil in your refrigerator.
Process of professional refilling of the system
The procedure for restoring tightness and charging refrigerant requires special equipment. The master connects a pressure gauge station and a vacuum pump to the process pipe. First, the system is checked with nitrogen under high pressure to make sure there are no other hidden leaks.
Then the air is pumped out of the circuit for 20-30 minutes. This is a critical step because moisture in the air will turn into ice at low temperatures and block circulation. After evacuation, liquid refrigerant is charged liquid refrigerant through a scale, since the volume must be maintained to the nearest gram.
☑️ Signs of a quality repair
After refilling, the system starts up, and the master controls the suction pressure and discharge, as well as the temperature of the nodes. Only after ensuring stable operation is the service pipe sealed. The whole process takes from 1 to 3 hours, depending on the difficulty of access to the evaporator.
Frequently asked questions (FAQ)
Can the liquid in the compressor run out on its own?
No, the refrigerant is not consumed during operation, like gasoline in a car. It's a vicious cycle. If the gas has escaped, it means that the tightness of the circuit has been compromised (through corrosion, mechanical damage, burst seam). The system needs to be looked for and soldered.
Is it dangerous to breathe freon vapors?
In low concentrations typical of household leaks, modern freons (R134a, R600a) are not toxic. However, they displace oxygen. If there is a large leak in a small room, suffocation may occur. When heated, old freons can emit phosgene, a poisonous gas, so you should not be near an open fire near a running or leaking refrigerator.
Why did the refrigerator begin to freeze worse after refilling?
Most likely, the repair technology was violated. Possible reasons: evacuation was not done (moisture remained), the wrong type of gas was filled, the amount was incorrectly selected (underfilling or overfilling), or the capillary tube is clogged with oil breakdown products.
How much does it cost to replace the liquid in the refrigerator?
The cost consists of the price of the refrigerant itself, the cost of work on finding leaks, soldering and vacuuming. The price is not fixed and depends on the model of the refrigerator and the difficulty of access to the evaporator (sealed in foam or open).