Many users, faced with an increase in temperature in the refrigerator compartment, mistakenly believe that the device simply stopped producing cold due to old age or a broken compressor. However, in the vast majority of cases, the problem lies not in mechanical wear, but in the banal absence of a working substance in the circuit. It is this substance, circulating through the system, that takes heat from the interior of the chamber and releases it to the environment. Without it, the compressor will run empty, and the products will begin to deteriorate.
The process of restoring the unit’s functionality is often called “refueling,” although it is more technically correct to talk about refilling or replenishing the circuit. refrigerant. It is important to understand that a refrigerator is a closed, sealed system, and the substance inside it is not consumed like fuel in a car or water in a kettle. If the gas has disappeared somewhere, it means that a microscopic crack or depressurization has formed somewhere, which must be found and eliminated before adding a new portion.
In this article we will look in detail at what gases are used in modern and old equipment, why you can’t fill in “just anything” and what the professional process of restoring the circuit looks like.
Independent experiments with pressure cylinders are dangerous not only for health, but also for the environment, so knowledge of the theory will help you competently monitor the work of a technician or make the right decision about the advisability of repairs.
The principle of operation and the role of the refrigerant in the system
To understand what exactly the system is filled with, you need to briefly consider the physical principle of operation refrigeration cycle. The basis of the process is the ability of a liquid to boil and turn into gas at very low temperatures, if an appropriate vacuum is created. In the evaporator, which is located inside the freezer or on the back wall, the liquid refrigerant boils, actively absorbing heat from the products.
After the evaporator, the gaseous substance enters the compressor, where it is compressed, heating up sharply and turning into a state of high pressure. The hot gas then passes through the condenser (black grille at the back), where it cools and turns into liquid again, releasing heat into the kitchen. This cycle is repeated continuously while the motor is running.
The key parameter here is boiling point the working substance. It determines how low the temperature your refrigerator can produce. Different gases have different physical properties, environmental friendliness and compatibility with tube materials and oil.
⚠️ Attention: An attempt to start the refrigerator without refrigerant or with its critically low level can lead to overheating and combustion of the compressor, since oil for lubricating rubbing parts circulates with gas.
Modern models require strict adherence to dosage. Even a slight deviation from the norm of 10-15 grams can disrupt heat transfer, cause the formation of an ice plug or a “liquid shock” on the compressor. Therefore, the question “what is used” is always inextricably linked with the question “how much is needed.”
Main types of refrigerants: from Freon to Isobutane
In everyday life, all gaseous substances used in refrigerators are usually called “freon”. However, Freon is a trademark of DuPont, and is technically a group of halogenated alkanes. Over decades of industry development, compositions have changed for the sake of efficiency and ecology. Old Soviet refrigerators worked on R12which cools perfectly, but destroys the ozone layer.
Modern technology has switched to safer analogues. The most common one now is R134a (tetrafluoroethane). It is non-flammable, non-toxic under normal conditions and has good refrigeration properties. It is this gas that is used to fill most models in the mid-price segment produced in the last 20 years.
The third popular type is R600a (isobutane). This is a hydrocarbon gas that is an excellent refrigerant, but has one serious drawback - it is explosive when mixed with air. The concentration of isobutane in one refrigerator is small (about 30-60 grams), which does not pose a threat in an open space, but requires special care when soldering.
Why is R600a so popular if it is flammable?
Isobutane has high cooling capacity and low pressure in the system, which makes compressors quieter and more economical. In addition, it is cheaper to produce and does not harm the environment.
The choice of a specific type of gas depends on the design of the system and the type of compressor oil used. Mixing different types of refrigerants is strictly prohibited, as this leads to a chemical reaction, the formation of acids and complete failure of the unit.
Table of compatibility and characteristics of gases
When diagnosing a leak, the technician always looks at the nameplate (sticker) on the back of the unit, which indicates the type of gas required. Using the wrong substance may result in the refrigerator simply not being able to reach the desired temperature or the compressor working with overload.
| Refrigerant type | Chemical name | Safety | Where used |
|---|---|---|---|
| R12 | Dichlorodifluoromethane | Toxic when burned | Old Soviet models |
| R134a | Tetrafluoroethane | Safe | Modern two-compressor |
| R600a | Isobutane | Explosive | Economical models (Indesit, Beko) |
| R407C | Mixture of gases | Conditionally safe | Industrial and old systems |
It is important to note that pressure in the system, different gases also differ. For example, for R134a it is higher than for R600a. Therefore, manifolds and scales must be calibrated for the specific type of substance. An error in setting up the equipment will lead to incorrect charging.
If your refrigerator used R12, replacing it with modern analogues requires not only replacing the gas, but also completely flushing the system and changing the oil, since old mineral oils are not compatible with new synthetic refrigerants.
Why gas evaporates: searching for leaks
As already mentioned, in a working refrigerator the gas does not disappear for decades. If refueling is required, it means that the tightness of the circuit is broken. The most common places for leaks are the soldering joints of the tubes, where a microcrack may have formed over time due to vibration or corrosion. The evaporator also often suffers, especially in models with a “crying” wall, where the tubes are mounted directly into the foam of the housing.
The second common culprit is metal corrosion. Moisture that gets on the back grill of the condenser or on the tubes in the foam part will destroy the thin metal over the years. As a result, a fistula is formed through which the gas slowly but surely escapes. This process can last from several months to a year until the refrigerator completely stops freezing.
☑️ Signs of a refrigerant leak
Diagnostics of a leak is a complex process. The technician pumps nitrogen into the system under high pressure (about 10-15 atmospheres) and listens to see if air comes out. Often, a soap solution is used for searching, which bubbles at the defect site, or special electronic leak detectors that react to freon molecules.
Sometimes a leak occurs in the foamed part of the housing. In this case, the repair becomes economically unfeasible, since it requires opening the insulation or installing an external evaporator (“weeping cap”), which spoils the appearance and reduces the usable volume.
Technology for professional refilling of the refrigerator
The refilling process is not just “opening the tap and letting the gas in.” This is a strictly regulated technological operation that requires special tools. The first step is always vacuum. Before introducing new gas, all air and, most importantly, moisture must be removed from the system. Moisture in the system is lethal: freezing in the capillary, it forms an ice plug that blocks circulation.
For evacuation, a vacuum pump is used, which is connected to the service fitting. The pump runs for 20 to 40 minutes, creating a deep vacuum at which water boils at room temperature and evaporates. Only after this the system is ready for filling.
Filling is carried out strictly according to the scales. The weight of the refrigerant in grams is always indicated on the compressor or in the instructions (for example, 130g ± 5g). The technician places the cylinder on an electronic scale and releases the gas until the desired value is reached. Overfilling or underfilling is equally harmful to the operation of the unit.
After filling, the capillary tube is sealed and the system is tested for functionality over a period of time. The master must make sure that the pressure in the system is stable and the temperature in the chambers drops to the specified values.
⚠️ Attention: In systems with isobutane (R600a), all soldering work should be carried out only after complete evacuation and purging, since the residual gas can ignite from the open flame of the burner.
Cost of work and feasibility of repair
Owners are often interested in how much it will cost to restore the cold. The price consists of the cost of materials (gas, solder, filter drier) and the complexity of the work (search for leaks, access to sealed places). The gas itself is relatively inexpensive, the bulk of the amount comes from the labor of a master and the use of expensive equipment.
If the refrigerator is old (over 10-12 years old) and the leak occurred in the foamed part of the body, repairs can cost up to 50-70% of the price of a new device. In such cases, it is often more profitable to purchase new equipment that will be more energy efficient and quiet.
However, if the problem is in an accessible place (for example, a pipe has burst in a visible place or a valve has failed), then repairs are completely justified. A modern high-quality compressor can operate for 15-20 years, and there is no point in changing it because of a trifling hole in the tube.
It is also worth considering the warranty. After professional refilling, service centers usually provide a guarantee from 6 months to 2 years on the work performed and the tightness of the system.
FAQ: Frequently Asked Questions
FAQ: Frequently Asked Questions
Is it possible to refill the refrigerator yourself from a spray can?
Theoretically, it is possible if you have equipment (scales, pressure gauges, vacuum pump) and soldering skills. However, without vacuuming, you will drive moisture into the system, which will kill the compressor in a couple of months. In addition, buying a freon cylinder for a one-time refill is not economically feasible.
Why did the refrigerator stop freezing after defrosting?
If you defrosted the unit with a knife or sharp objects and accidentally pierced the wall, a hissing sound started and the smell of almonds or chemicals appeared - you have broken the evaporator. The gas is out, soldering and refueling are needed. If you just defrosted and waited, the thermostat or start relay may have burned out.
How often do you need to change or add freon?
In a working refrigerator, freon never needs to be changed or added. It circulates in a closed loop. If the gas has disappeared somewhere, it means that an accident (leak) has occurred that needs to be repaired.
Is freon dangerous for humans?
Modern freons (R134a) are low-toxic, but in high concentrations they displace oxygen, causing suffocation. Isobutane (R600a) is explosive. Old freons (R12) release phosgene, a chemical warfare agent, when in contact with an open fire. Therefore, any work should be carried out in a ventilated area.