A modern household refrigerator is a complex thermodynamic system, the operation of which is impossible without a substance circulating inside a sealed circuit. Many equipment owners mistakenly believe that inside the tubes there is simply compressed air or steam, but in fact, a special one is used, which is capable of changing its state of aggregation at different temperatures and pressures. It is this process of phase transition from liquid to gas and back that allows heat to be removed from the internal chamber and released into the environment. refrigerant, capable of changing its state of aggregation at different temperatures and pressures. It is this process of phase transition from liquid to gas and back that allows heat to be removed from the internal chamber and released into the environment.
If you are wondering what is put into the refrigerator, it is important to understand that we are not talking about one component, but about a strict combination of the working fluid and the lubricant. Freon (as refrigerants are often called in everyday life) must have certain physical properties in order to work effectively in the compressor, condenser and evaporator. Without the correct chemical composition, the system either will not cool or will fail in a matter of minutes.
In this article we will analyze in detail what substances are used in modern and old models of refrigeration units. You will learn why you cannot mix different types of gases, what role compressor oil plays and what to do if the system has lost its seal. It is critically important to know the exact brand of refrigerant indicated on the nameplate of your device, since charging with the wrong gas can lead to an explosion or fire.
Main working fluid: types refrigerants
The main component that circulates through the tubes is the refrigerant - a volatile liquid with a low boiling point. In household refrigerators of the last century and the early 2000s, R12 (difluorodichloromethane) was widely used. This substance was considered ideal because of its inertness and safety, but it was later discovered that it destroys the Earth's ozone layer. Therefore, its production was prohibited by the Montreal Protocol.
R12 was replaced by R134a (tetrafluoroethane), which became the standard for most refrigerators produced from the mid-90s to the 2010s. This gas does not destroy the ozone layer, but has a high global warming potential. In modern models, especially in No Frost systems and inverter compressors, mixtures such as R600a (isobutane) are increasingly used. It is a hydrocarbon gas that is very effective but highly flammable.
⚠️ Caution: R600a (isobutane) is explosive when concentrated in air. Repairing such systems requires special equipment and non-sparking tools. Do not try to bleed gas yourself or solder pipes without pumping out!
Differences between refrigerants lie not only in the chemical formula, but also in operating pressure and compatibility with oils. Replacing one type with another is possible only with a complete rework of the system (replacing the compressor, flushing the circuit and replacing the filter-drier), which is not economically feasible in domestic conditions.
Lubricants materials for the compressor
The second critical element that is “charged” into the system along with the gas (or that is already in the compressor) is oil. It is necessary to lubricate the rubbing parts of the motor-compressor, remove heat and ensure the tightness of the gaps between the piston and the cylinder. The main feature of refrigeration oils is their ability to dissolve in the refrigerant and return back to the compressor without getting stuck in the evaporator.
For different types of freons, fundamentally different oil bases are used. For old systems on R12 and modern systems on R134a, synthetic polyester oils (POE) or highly purified mineral oils are used. They are hygroscopic, that is, they actively absorb moisture from the air, which makes their replacement a complex procedure that requires evacuation of the system.
In systems operating on hydrocarbons R600aspecial mineral oils with low viscosity or alkylbenzene are most often used mixtures. They are less demanding on humidity, but they cannot be mixed with polyester analogues. An attempt to add “just some oil” will lead to the formation of an acidic environment, varnish deposits and rapid failure of the compressor.
- 🛢️ Mineral oils: used with R12 and partially with R600a, are not hygroscopic, but do not mix well with modern synthetic freons.
- 💧 Polyester (POE): required for R134a and R410a, have excellent lubricity, but require absolute dryness of the system.
- ⚗️ Alkylbenzene (AB): transitional type of oils, often used in retrofitting (conversion) of old systems for new refrigerants.
How to determine the type of refill of your refrigerator
Before thinking about repair or refilling, you need to accurately identify the substances used in your model. Manufacturers are required to indicate this information on a special marking plate (nameplate). Usually it is located inside the refrigerator compartment on the side wall, on the back wall or on the plinth at the front.
On the nameplate you should be interested in the fields Refrigerant or Refrigerantwhere the brand of gas is indicated (for example, R600a), and the field Charge or Filling weight, which shows how many grams of the substance should be in the system. The type and amount of oil is also often indicated, although in household repairs it is changed along with the compressor.
It is important to pay attention to the color marking of the service pipe (if there is one) or gas cylinder, although there are no cylinders in the finished product. R134a is characterized by a light blue label color, while R600a is characterized by red or orange, warning of a fire hazard.
| Refrigerant type | Chemical base | Ignition potential | Typical application |
|---|---|---|---|
| R12 | Freon (CFC) | Non-flammable | Old refrigerators (before 1995) |
| R134a | HFC (HFC) | Not flammable | Most refrigerators (1995–2010) |
| R600a | Hydrocarbon | Highly flammable | Modern energy-efficient models |
| R404A | Mixture HFC | Non-flammable | Industrial and freezers |
Refilling process and necessary tools
Refilling a refrigerator is not just “pumping” gas, like into a car tire. This is a technological process that requires vacuum and precise dosage. The technician must first find and repair the leak, otherwise the new gas will escape within a few days or weeks. Then the system is subjected to deep evacuation to remove air and moisture.
To carry out the work, specialized tools are used: a vacuum pump, a pressure gauge station (manifold), electronic scales and a supply of refrigerant in the cylinder. Scales are necessary because refueling is carried out strictly by mass (in grams), and not by pressure, since the pressure depends on the ambient temperature.
☑️ Tools for refueling
The process is as follows: a hose from a vacuum pump is connected to the service pipe. The pump is turned on for 15–30 minutes, creating a vacuum at which water in the system boils and evaporates even at room temperature. Only after this the valve of the freon cylinder opens and the gas is released into the system under the control of the scale.
⚠️ Attention: The pressure parameters in the system are dynamic and depend on the condensation temperature. It is impossible to judge the lack of freon only by the pressure gauge readings without analyzing the compressor current and the temperature at the outlet of the evaporator.
Signs of a leak and the need for maintenance
How to understand that the gas has “gone”? The sealed circuit of the refrigerator is designed to operate for 10–15 years without refueling. If you notice that the refrigerator has started to work worse, this is an alarming signal. Unlike a car, where oil or antifreeze consumption may be normal, in a refrigerator a leak is always a malfunction.
Symptoms of a lack of refrigerant can vary. In systems with a crying evaporator, the water on the back wall stops freezing. In No Frost systems, the formation of frost on the evaporator inside the housing stops, and the chamber becomes warm. In this case, the compressor can work continuously, trying to gain temperature, and become very hot.
- ❄️ Weak cooling: products begin to deteriorate, the temperature in the chamber is higher than the set temperature.
- 🔊 Constant hum: the motor hums without interruption, without turning off for rest.
- 🔥 Hot condenser: the grille at the back (or on the sides) is only partially hot or completely cold.
- 💧 Lack of cycle: in two-compressor models, one of the compressors does not start or runs idle.
Often a leak occurs in the foamed part of the housing (internal tubes of the evaporator) or at the point where the tubes enter the cabinet (corrosion). In the first case, repairs are complicated and expensive, in the second, it is enough to overcook the joint. Diagnostics requires experience and equipment.
Is it possible to refuel the refrigerator yourself?
Theoretically, it is possible if you have access to gas and tools. However, without searching for leaks and vacuuming, the system will quickly fail. Moisture remaining in the circuit will turn into an ice plug in the capillary, blocking circulation.
Environmental aspects and the future of refrigerants
The refrigeration industry is in the process of constant transformation. After the abandonment of R12, the world was faced with the problem of the greenhouse effect from R134a. Now we are seeing a transition to natural refrigerants, such as R600a (isobutane) and R290 (propane). They do not affect the planet's climate, but require increased care during production and disposal.
Leading manufacturers are already testing new mixtures with even lower global warming potential. The future belongs to substances that are completely safe for the atmosphere, even if they are flammable. This dictates new safety standards: reducing the amount of gas charged, using intrinsically safe electronics and improving ventilation in places where equipment is installed.
Owners of old refrigerators should think about their recycling. Old freons released into the atmosphere due to improper disassembly cause enormous harm. By handing over equipment to specialized points, you contribute to the correct processing of hazardous substances.
Is it possible to mix different types of freon?
It is strictly forbidden. Mixing R134a and R600a (or R12) will change the thermodynamic properties of the mixture, increase the pressure in the system and, most likely, cause destruction of the compressor or explosion. In addition, different freons require different oils, which can coagulate upon contact.
Why does the refrigerator not cool after refilling?
There may be several reasons: an incorrectly selected dose (too little or too much gas), the presence of an air lock in the system, a clogged capillary tube or moisture in the circuit. There may also be a malfunction of the compressor itself, which does not create the required pressure.
How often do you need to change freon in a refrigerator?
In a working refrigerator, freon never needs to be changed. This is a closed system. If the gas has gone somewhere, it means a hole (leak) has formed. Simply “adding” gas without eliminating the cause of the leak is a temporary measure that will extend the life of the unit by several weeks.
Is freon from a household refrigerator dangerous for humans?
Modern freons (R134a, R600a) in small quantities contained in a household refrigerator (50–150 grams) are not toxic after short-term inhalation. However, R600a is explosive. Old R12, when in contact with an open flame, can form phosgene, a chemical warfare agent. Therefore, heating the tubes with an open fire is prohibited.