The question of what kind of liquid is inside the circuits of your refrigerator often arises among equipment owners when malfunctions occur or simply out of curiosity about the design of household appliances. Many people mistakenly believe that it is water or some simple cooling substance available in the nearest store. In fact, the internal “circulatory system” of the refrigerator is filled with special gases and technical liquids operating under high pressure.
Understanding the nature of these substances is critical not only for proper operation, but also for ensuring the safety of household members. Modern refrigeration units use complex chemical compounds, which, if leaked, can be dangerous, and if replaced incorrectly, can damage expensive equipment. In this article we will analyze in detail what exactly circulates inside the tubes and compressor.
The basis of the working fluid is refrigerant, often called freon in everyday life. This substance has the unique ability to change its state of aggregation at different temperatures and pressures, taking heat from the fridge compartment and releasing it into the environment. It is this cycle that allows us to keep food fresh for a long time.
The main refrigerant: what is freon
The main substance that provides cooling is freon the general name of a group of saturated aliphatic fluorinated hydrocarbons. Older refrigerator models commonly used R-12, which had excellent refrigeration properties, but was considered harmful to the planet's ozone layer. Modern manufacturers have switched to more environmentally friendly, but more complex analogues.
Today you can most often find R-134a or isobutane R-600ain household refrigerators. The latter is becoming the de facto standard due to its high energy efficiency and minimal environmental impact. However, unlike its predecessors, isobutane is a flammable gas, which imposes special requirements on the tightness of the system and the qualifications of the technicians during repairs.
The physical properties of these gases allow them to easily pass from a gaseous state to a liquid state and back. In the condenser (grid at the back), the gas cools and turns into liquid, giving off heat. Then, passing through a capillary tube and an evaporator inside the chamber, the liquid boils at low pressure, actively absorbing heat from the products.
⚠️ Attention: Freon is colorless and odorless in normal concentrations, so it is almost impossible to detect its leak by external signs without special equipment. If the refrigerator has stopped freezing, but the compressor is working, most likely the circuit has depressurized.
It is important to understand that different brands of freon are not interchangeable. Filling a refrigerator designed for R-600awith gas R-134a will lead to overload of the compressor and eventual breakdown of the unit. The condensation and boiling pressures of these substances differ, which requires strict adherence to the manufacturer's specifications.
Compressor oil: system lubrication
Unlike the refrigerant, which circulates throughout the circuit, the oil is located primarily in the compressor crankcase. However, a small part of it is always in the system in the form of a suspension, moving along with the freon flow. The main task of this fluid is lubrication the rubbing parts of the motor-compressor and removing heat from them.
There is a common misconception that any mineral or synthetic oil can be poured into the system. This is categorically untrue. The chemical composition of the oil must be strictly compatible with the type of freon used. For example, mineral oils were used for R-12 freon, which did not mix well with it.
Modern refrigerants, such as R-134a and R-600a, require the use of synthetic oils based on polyesters (POE) or polyvinyl ether (PAG). These oils are highly hygroscopic, meaning they actively absorb moisture from the air. The entry of even a small amount of moisture into a system with polyester oil can lead to the formation of acids that will destroy the motor windings and clog the capillary tube.
What happens if you mix different types oils?
Mixing mineral and synthetic oils can lead to sediment that will clog the filter drier and capillary tube. This will cause refrigerant circulation problems and compressor overheating, which will require an expensive system flush or compressor replacement.
The oil level in the compressor also plays a critical role. Its excess can lead to water hammer, since liquid, unlike gas, is not compressed. A lack of oil will cause dry friction, overheating and jamming of the piston group. That is why changing the oil on your own without vacuuming the system is prohibited.
☑️ Signs of problems with oil in the compressor
Compatibility table of refrigerants and oils
For proper maintenance and understanding which fluids are used in a particular model, you need to know their compatibility. Below is a table showing the main vapors used in refrigeration equipment of different generations.
| Refrigerant type | Type of required oil | Chemical base | Application features |
|---|---|---|---|
| R-12 (Freon 12) | Mineral | Petroleum base | Outdated, prohibited due to ozone-depleting effects |
| R-134a | Synthetic (POE/PAG) | Polyester | Requires complete tightness, is afraid of moisture |
| R-600a (Isobutane) | Mineral / Alkylbenzene | Hydrocarbon | Flammable gas, used in modern quiet models |
| R-407C | Synthetic (POE) | Freon mixture | Used in industrial and large household systems |
The table shows that the transition to new environmental standards required changes and lubricants. If your refrigerator uses R-134a, then during repairs the technician must use only the appropriate synthetic oil and a new filter-drier, since the old one could already be saturated with moisture.
Incompatibility of components is one of the main reasons for repeated breakdowns after unqualified repairs. An attempt to fill the R-600a system with R-12 oil will lead to stratification of the mixture and a lack of lubrication in critical compressor components.
Water in the system: enemy or necessity?
Many users wonder whether water can be poured into the refrigerator. The answer is clear: water is not poured into the refrigeration circuit. The ingress of water into the freon circulation system is an emergency. never water does not fill. Water getting inside the freon circulation system is an emergency.
The reason lies in the physics of the process. The system has a narrow part - a capillary tube or thermostatic valve. Temperatures there can drop below zero. If there is water in the circuit, it will freeze, forming an ice plug. This completely blocks the circulation of the refrigerant, and the refrigerator stops cooling.
⚠️ Attention: Water in the system leads to a chemical reaction with oil and freon, resulting in the formation of aggressive acids. They corrode the insulation of the electric motor windings and metal parts, causing a “copper coating” of steel surfaces and breakdown of the compressor.
The only place where liquid water is present in the refrigerator is the No Frost system (in some models) or conventional drip systems, where condensate flows into the evaporation tank. But this is water from the chamber air, and not the working fluid of the cooling system.
How to determine a leak and what to do
Understanding what kind of liquid is inside helps diagnose problems. Since freon circulates in a closed circuit, its quantity should not decrease during operation. If the refrigerator begins to freeze worse or stops turning off, there is most likely a leak.
Leakage can occur due to corrosion of the evaporator (especially in models with a foamed circuit), mechanical damage to the tubes during defrosting or vibration. In places where gas escapes, you can often (but not always) notice oily spots, since freon carries microparticles of compressor oil with it.
To find leaks, technicians use:
- 🔍 Electronic leak detectors that react to halogens.
- 🧼 Soap solution for visualization bubbles.
- 🎈 Nitrogen to create excess pressure in the system.
- 🌫️ Ultraviolet paint added to the oil (professional method).
It is extremely difficult to independently find and repair the leak, and then refill the refrigerator. This requires a vacuum pump, a pressure gauge station and a scale for gas dosing. Without evacuation, air and moisture will remain in the system, which is guaranteed to lead to compressor failure in a short time.
⚠️ Attention: Never try to pierce the pipes yourself or solder them without removing the refrigerant. The release of gas under pressure can be dangerous, and the use of an open flame near the remains of flammable freon (R-600a) can cause an explosion.
Ecology and safety during maintenance
Modern environmental requirements dictate the rules for recycling old refrigerators. Freon released into the atmosphere contributes to global warming (the greenhouse effect), even if it does not destroy the ozone layer like older brands. Therefore, when decommissioning equipment, the liquid must be pumped out by specialists.
Isobutane is particularly dangerous. R-600a. Although it is not toxic, it forms an explosive mixture with air. A concentration of only 30-40 grams of this gas in a small room in the presence of a spark (for example, from a refrigerator relay or light switch) can lead to a bang.
Therefore, the instructions for modern refrigerators contain strict warnings about prohibiting self-repair of the circuit. If you smell gas (although pure freon does not smell, sometimes odorants are added, or the smell may come from burnt insulation during a leak), you need to ventilate the room and do not turn on electrical appliances.
In conclusion, it is worth noting that the “liquid” in the refrigerator is a high-tech engineering solution that requires a professional approach. The correct mixture of refrigerant and oil ensures a long compressor life and stable temperatures for your food.
Frequently asked questions (FAQ)
Is it possible to add freon to the refrigerator if it does not freeze well?
You cannot simply “add” freon. First, you need to find and eliminate the cause of the leak, replace the filter drier, evacuate the system, and only then charge a strictly defined amount of refrigerant. Without eliminating the leak, the gas will come out again.
Is freon from an old Soviet refrigerator dangerous for humans?
Freon R-12, used in older models, is not toxic under normal conditions. However, upon contact with an open flame, it can decompose to form phosgene, a chemical warfare agent. Therefore, tubes can be soldered only after complete removal of gas from the system.
Why can’t you mix different brands of oils in a compressor?
Different oils have different chemical structures and viscosities. Mixing them can lead to loss of lubricating properties, the formation of sludge that clogs the thin channels of the system, and a chemical reaction that destroys the engine insulation.
How often do you need to change the liquid (freon) in the refrigerator?
Freon is a working fluid in a closed cycle and is not consumed. It needs to be changed only in case of repairs associated with depressurization of the circuit. In a working refrigerator, the refrigerant is never replaced.