Loss of cold in the refrigerator is always stressful, because food supplies are at risk. When the compressor runs without stopping, and the temperature inside the chamber remains at room temperature, an experienced user immediately suspects a leak refrigerant. Many owners of household appliances are thinking about doing their own repairs, wanting to save on calling a technician or simply out of interest in the design of the unit. However, the process of restoring the tightness of the system and filling with gas requires not only special tools, but also a deep understanding of the physical processes.
Before taking active steps, it is necessary to clearly understand that Freon (refrigerant) is not just gas, but the working fluid of the refrigeration machine, circulating under pressure. Modern refrigerators, whether classic or complex systems, use different types of gases, most often R600a (isobutane) or R134a. An error in choosing a substance or a violation of the filling technology can lead to breakdown of the compressor or, in the case of isobutane, to an explosive situation. Atlant or complex systems No Frost from Liebherr, use different types of gases, most often R600a (isobutane) or R134a. An error in the choice of substance or violation of the filling technology can lead to compressor failure or, in the case of isobutane, to an explosive situation. Tightness circuit is the first thing that needs to be ensured before manipulating the gas.
In this article we will analyze in detail the technical side of the issue, explain why simply “adding gas” from a can is often not enough, and describe the process of vacuuming the system. You will learn what tools are required for the job, how to determine the type of refrigerant from the nameplate, and why system pressure is a critical parameter. Remember that quality diagnosis always precedes repair, and ignoring this stage negates all further efforts.
Diagnostics of leaks and preparation of equipment
The first step in the process of restoring the functionality of the refrigerator is to find a place where where the gas left the system. Just like that, for no reason, freon it doesn’t go anywhere, since the circuit is sealed. Most often, leaks occur in the foamed part of the housing (evaporator) or in the condenser (black grille at the back). To detect fistulas, technicians use a soap solution or special leak detectors that react to refrigerant vapors. Visual inspection of the tubes for oily stains can also indicate a problem, since the gas circulates along with the compressor oil.
To carry out the work, you will need a specific set of tools, which are rarely found in an ordinary home workshop. Without vacuum pump and pressure station (collector) there is no point in starting work. You will also need a pipe cutter, a copper pipe rolling machine, a soldering torch and, of course, a cylinder with a suitable type of freon. The use of unsuitable equipment can lead to moisture entering the system, which will cause the formation of ice plugs and failure of the capillary tube.
⚠️ Attention: Before starting any work on soldering or disassembling the refrigerator, be sure to disconnect the unit from power grid! Working with open flames and electrical components at the same time is strictly prohibited.
It is also important to prepare the workplace. The refrigerator must be moved away from the wall, providing access from all sides. If the model is equipped with the No Frostsystem, partial disassembly of the interior may be required to access the evaporator. Make sure the area where you will be working is well ventilated, especially if you plan to work with flammable gas R600a. The concentration of gas in the air should not exceed permissible standards.
Types of refrigerants and their features
Understanding exactly what gas is used in your refrigerator is critical to the success of the operation. In modern household refrigerators, the two most common types of refrigerants are: R134a (tetrafluoroethane) and R600a (isobutane). R12 (freon) used to be widely used, but it is banned from production due to its destructive effects on the ozone layer. It is strictly forbidden to mix different types of gases, since they have different chemical structures, boiling pressures and, most importantly, different oils for lubricating the compressor.
R134a refrigerant is standard for most middle-class refrigerators. It is non-flammable, but requires the use of synthetic oil POE (polyester), which is very hygroscopic, that is, it actively absorbs moisture from the air. Even a small amount of moisture entering a system with R134a leads to the formation of acid, which corrodes the motor windings and clogs the capillary. The pressure in the system with this gas is higher than that of analogues, which requires more careful checking of connections for leaks.
Isobutane (R600a) is becoming increasingly popular due to its energy efficiency and environmental friendliness. However, it explosive gas. Its concentration in the air of only 1.3% already creates an explosive mixture. Therefore, when filling the refrigerator with isobutane, it is prohibited to smoke, use sparking tools, and turn on the light in an unventilated area. The amount of gas in such systems is very small (often less than 100 grams), so an error in dosage of even 10 grams can be fatal to the performance of the unit.
| Parameter | R134a (Tetrafluoroethane) | R600a (Isobutane) | R12 (Dichlorodifluoromethane) |
|---|---|---|---|
| Flammability | Non-flammable | Flammable | Non-flammable |
| Oil type | POE (synthetic) | Mineral | Mineral |
| Pressure (at 25°C) | ~6.5 bar | ~3.5 bar | ~6.0 bar |
| Environmentally friendly | Safe for ozone | Safe for ozone | Destroys the ozone layer |
When choosing a cylinder for refilling, always rely on the markings on the nameplate of the refrigerator, which is usually located on the back wall or inside the chamber. Using gas with an unsuitable chemical composition will lead to incorrect operation of the thermostat and possible destruction of the compressor seals. Never try to fill the refrigerator with automobile freon or lighter gasas their composition and impurities are not intended for long-term operation in high-precision refrigeration circuits.
The process of vacuuming the system
Vacuuming is perhaps the most important step in the entire refueling procedure, which is most often ignored by beginners. After soldering new tubes or replacing the filter-drier, air and moisture vapor remain inside the circuit. The air contains nitrogen and oxygen, which do not condense at the operating temperatures of the refrigerator, creating a so-called “air lock”. This leads to a sharp increase in discharge pressure, overheating of the compressor and improper heat transfer.
To remove air, a vacuum pump is used, which is connected to the service fitting through a pressure manifold. The process is as follows: after all connections are soldered or threaded, a pump is connected to the system. Turning on the unit allows gases to be drawn out of the circuit. The pressure should drop to a deep vacuum (usually below -0.1 MPa or 750 mmHg on a vacuum gauge). The evacuation time depends on the volume of the system, but usually ranges from 15 to 30 minutes.
☑️ Evacuation checklist
Moisture is the main enemy of the refrigeration system. At low temperatures in the capillary tube, it turns into ice, completely blocking the circulation of freon. Vacuuming allows you to lower the boiling point of water, turning it into steam and removing it from the system. If a vacuum pump is not used and the gas is simply vented to force out the air, the effectiveness of this method is extremely low and the risk of moisture ingress remains high. High-quality draining guarantees a long life for the compressor.
⚠️ Attention: After reaching a vacuum, you cannot simply turn off the pump without first closing the valve on the manifold. Otherwise, the oil from the pump may be drawn back into the refrigerator circuit, which will require a complete flushing of the system.
Refrigerant charging technology
After successful vacuuming, the refueling stage begins. Accuracy is important here, especially when it comes to isobutane. There are two main charging methods: by mass and by pressure/temperature. Refilling by mass is considered the most accurate and professional. To do this, a cylinder with freon is installed on an electronic scale, and exactly as much gas is released into the system as indicated in the technical documentation (for example, 65 grams). Overfilling or underfilling is equally harmful to performance.
If scales are not available, experienced craftsmen rely on the suction pressure and temperature of the evaporator housing. However, this method requires experience and an understanding of how a specific refrigerator model behaves. Gas is supplied in small portions while the compressor is running. It is important to ensure that the liquid phase of freon does not enter the compressor, only the gaseous phase. To do this, the cylinder is sometimes turned over (if filling with the liquid phase through a receiver) or held upside down, but the process is monitored very carefully.
Nuances of filling R600a
When working with isobutane, it is better to fill in the liquid phase through the bottom of the cylinder, but in very small portions, allowing the gas to evaporate in the heat exchanger before entering the compressor. This minimizes the risk of water hammer. Also, all connections must be made by soldering; any threaded connections inside the circuit with R600a are undesirable due to the risk of sparking and leaks.
During the refueling process, it is necessary to constantly monitor the current consumption of the compressor. It must not exceed the ratings indicated on the engine tag. If the current increases but no cold appears, there may be an air lock in the system or a clogged capillary tube. You should also feel the condenser: it should warm up evenly from top to bottom. The presence of cold spots on a hot grate may indicate a blockage or incorrect amount of refrigerant.
Operation control and sealing
After the required amount of gas has been charged, you need to disconnect the charging station. At this point, it is important to act quickly and accurately to minimize gas loss and air entry. The service pipe through which the refueling was carried out is cut or sealed. If the cutting method is used, the cut area is immediately clamped and sealed. Any microscopic gap will become a path for a new leak, and all the work will go down the drain.
The final stage is to check the tightness of all connections made. To do this, use a soap solution, which generously lubricates the soldering areas and joints. The appearance of even small bubbles indicates a defect. You can also use an electronic leak detector, which “beeps” when freon vapor is detected. After checking, the refrigerator is left turned on for several hours to stabilize the pressure and temperature.
Normal operation of the refrigerator is characterized by cyclicity: the compressor turns on, cools the chambers to the set temperature, then turns off and rests. If the refrigerator runs non-stop, there may not be enough freon or there is air in the system. If it turns off too quickly, without having time to gain cold, it is likely to overcharge with gas. The optimal operating mode is selected experimentally, but is based on factory standards.
Frequent errors and risks when refueling yourself
Refilling the refrigerator yourself is full of risks that you should know about in advance. One of the most common mistakes is neglecting to replace the filter drier. This element collects moisture and oil breakdown products. When the circuit is opened, the old filter is saturated with moisture from the air in seconds and stops working. Installing a new filter drier is mandatory for any depressurization of the system, otherwise moisture will quickly kill the compressor.
Another common problem is the use of the wrong oil. If the system contained R134a (requires synthetic POE oil), and the technician filled in mineral oil, or vice versa, separation of fractions will occur. The oil will stop returning to the compressor, causing it to seize due to dry friction. In addition, synthetic oils are aggressive to some types of rubber and plastic, so the compatibility of materials must be checked.
⚠️ Attention: Improper disposal of old freon is prohibited by law in many countries. Do not simply release remaining gas into the atmosphere. Although the volumes in household refrigerators are small, environmental responsibility lies with every owner of the equipment.
Also, do not forget about the safety of electrical wiring. During operation, you often have to remove the back panel where the wires and relays are located. Rough handling of the tool may damage the insulation. Before turning on for the first time after repair, carefully check the integrity of all electrical connections and the reliability of grounding of the case.
Is it possible to fill a refrigerator with a regular syringe or a can without a scale?
Theoretically, you can try to get into the pressure, but without a scale it is very difficult to determine the exact amount of gas. Modern refrigerators, especially those with R600a, require gram accuracy. Overfilling will lead to high pressure and load on the compressor, while underfilling will lead to insufficient cold. Using a syringe does not provide control over the gas phase (liquid or vapor), which is dangerous for the compressor.
How long should the refrigerator operate after refueling until it reaches temperature?
After refueling, the refrigerator may require from 2 to 6 hours for the first full cooling cycle and stabilization of the temperature. It is not recommended to load products at this time. If after 6-8 hours of operation of the compressor the temperature in the chambers has not dropped to normal values, it means that there is a malfunction in the system (an air lock, a clogged capillary, an incorrect amount of freon).
Why does the freezer work after refilling, but the refrigerator does not?
This is a common symptom of an incorrect amount of refrigerant (most often underfilling) or the presence of an air lock in the system. The problem may also lie in a malfunction of the sensors or the air distribution damper (in No Frost systems). If there is little freon, it has time to evaporate in the first circuit (freezer) and does not reach the second (refrigerator).
Is it dangerous to change freon yourself if there are children in the house?
The refilling process involves the use of gases that can be dangerous if inhaled in high concentrations, and tools (burner) that create an open fire. If you are not a professional, the risk of making mistakes is high. It is better to carry out work in the absence of children and in a well-ventilated area (garage, yard). After completing the work, be sure to check the connections for leaks.