The situation when the refrigerator stops freezing and the compressor hums idle or is completely silent often leaves the owner with a choice: call a technician or try to solve the problem on his own. Freon charging is this a technically complex process that requires not only special equipment, but also an understanding of thermodynamics. Many home craftsmen underestimate the risks associated with working under pressure and using chemicals, which can lead to equipment breakdowns or injuries.
Nevertheless, with a theoretical basis and a minimum set of tools, the procedure for replacing the refrigerant is feasible in a garage or home workshop. It is important to understand that this is not just about “topping up” gas, as in a car air conditioner, but about a complete replacement of the circulation circuit with preliminary vacuumization of the system. R600a and R134aused in modern models require special care due to their flammability or sensitivity to moisture.
Before you begin Before taking active action, it is necessary to conduct a thorough diagnosis. Often the lack of cold is caused not by a freon leak, but by a malfunction of the thermostat, start relay or compressor. If you are convinced that the tubes are dry and there is no pressure in the system, then restoring the tightness and charging with refrigerant become the only way out.
Diagnostics of leaks and preparation of the workplace
The first stage is always search for the location of depressurization. Freon is odorless and colorless, so it is impossible to detect it visually without special equipment. Most often, leaks occur in solder joints, on the evaporator (“crying” or foamed) or in the condenser grille at the back of the unit. For detection, use a soap solution or an electronic leak detector.
If bubbles do not appear and the pressure drops, a microcrack may be hidden in the foam layer of the housing. In such cases, craftsmen often decide to install an external evaporator (“crying” plate) instead of restoring the internal circuit. This allows you to avoid the labor-intensive process of opening the thermal insulation and its subsequent restoration.
Preparation of the workplace is critical for safety. The area should be well ventilated, as many modern refrigerants are heavier than air and can displace oxygen, creating a suffocation risk. It is also necessary to exclude sources of open flame, especially if you plan to work with isobutane (R600a).
⚠️ Attention: Working with refrigerants requires the use of protective glasses and gloves. Contact with liquid freon on the skin causes instant frostbite of tissue, comparable to a thermal burn.
To successfully carry out the work, you will need to collect the following arsenal of tools:
- 🛠️ Vacuum pump to remove moisture and air from the circuit.
- 🛠️ Manometric station (manifold) with hoses of the corresponding color.
- 🛠️ Cylinder with freon of the required brand (indicated on the compressor nameplate).
- 🛠️ Gas burner with solder and flux for soldering copper tubes.
- 🛠️ Electronic scales for precise dosing of refrigerant.
Necessary equipment and types of refrigerants
Choosing the right refrigerant is the foundation for a successful repair. Mixing different types of freons is strictly prohibited, as this leads to a chemical reaction, the formation of acids and rapid failure of the compressor. The marking is usually applied to a metal plate (label) attached to the compressor housing or inside the refrigeration chamber.
Modern household refrigerators are most often filled with two types of substances: R134a (tetrafluoroethane) and R600a (isobutane). The first is a safe analogue of the banned freon-12; it is non-flammable, but requires careful drying of the system. The second is a hydrocarbon that has excellent cooling performance, but is explosive when the concentration in air is more than 3%.
| Refrigerant type | Chemical name | Danger | System pressure |
|---|---|---|---|
| R134a | Tetrafluoroethane | Safe, does not burn | Average |
| R600a | Isobutane | Explosive, flammable | Low |
| R12 | Dichlorodifluoromethane | Outdated, harmful to the environment | High |
| R404a | Mixture of fluorocarbons | Does not burn, but displaces oxygen | High |
In addition to the gas itself, the quality of the oil in the compressor is critically important. If freon leaks for a long time, part of the compressor oil could also leave the system along with it, which will also need to be topped up. The type of oil must strictly correspond to the type of freon: for R134a synthetic polyester oil (POE) is used, and for old-style mineral oils it is not suitable due to the different chemical structure.
The process of soldering copper tubes and inserting a valve
After detecting and eliminating the leak (or replacing the evaporator), it is necessary to provide access to the system for pumping out air and pumping in gas. To do this, a Schrader service valve is cut into the compressor process tube (usually it is the shortest and has a sealed end). This allows you to connect the hoses of the pressure gauge station without breaking the seal in the future.
The soldering process requires skill. Copper melts at a high temperature, so the tube must be heated evenly, using filler material containing silver for greater weld strength. It is important not to overheat the soldering area so that oxide deposits do not form inside the tube, which can subsequently clog the capillary.
When installing the Schrader valve, make sure that the valve needle does not rest against the wall of the tube ahead of time, blocking the passage. After soldering the fitting, you need to check the quality of the connection under pressure by releasing a little gas or using nitrogen.
⚠️ Attention: When soldering next to the foamed body, use a damp cloth or heat-dissipating gel so as not to melt the polyurethane foam insulation and damage the plastic inner box of the refrigerator.
Safety precautions when working with open flames and gas require having a fire extinguisher on hand. Even if you are working with non-flammable freon, there may be other flammable materials in the room.
Evacuating the system: a critical stage
Many beginners make the fatal mistake of skipping the evacuation step or performing it insufficiently well. There should be no air and, most importantly, moisture left in the system. Water that gets into the refrigerant circuit freezes in the capillary tube, forming an ice plug that blocks circulation.
In addition, moisture reacts with oil and freon, forming aggressive acids that corrode the compressor windings from the inside. The vacuum process should last at least 30-40 minutes for household refrigerators. The vacuum pump creates a vacuum at which water boils and evaporates even at room temperature.
To control the process, use a low pressure gauge (blue). The needle should drop below zero, into the vacuum zone. If, after turning off the pump, the arrow begins to creep up, it means that there is a leak in the system, and the soldering must be repeated.
☑️ Evacuation checklist
There is a method of “purging” with freon when there are several systems once filled with gas and vented, displacing the air. However, this method is considered less efficient and more wasteful than using a quality vacuum pump. For a home handyman, having a pump is a prerequisite for quality repairs.
Technology for charging freon by weight and pressure
There are two main charging methods: by weight (weights) and by pressure/current. The most accurate and recommended by manufacturers is the weight filling method. The compressor nameplate always indicates the exact number of grams of refrigerant (for example, 65 g or 120 g). A deviation of more than 5-10 grams can lead to incorrect operation.
To implement this method, a freon cylinder is placed on an electronic scale. After taring the scales (taking into account the weight of the hose), the valve opens and gas enters the system. As soon as the scales show the desired value minus the weight of the hose, the supply is stopped. When working with R600a the cylinder often has to be turned over to supply the liquid fraction, but this requires extreme caution.
The pressure filling method is less accurate and depends on the ambient temperature. The pressure in the low-pressure system when the compressor is running must correspond to the boiling point of freon. For example, for R134a at an evaporation temperature of -20°C, the pressure will be about 1.1-1.2 bar. However, relying only on a pressure gauge is risky without experience.
Why can’t you fill it “by eye”?
The amount of freon affects the boiling point. If there is not enough gas, the compressor will work non-stop, trying to gain temperature, and will burn out. If there is a lot of gas, liquid freon can enter the compressor, causing water hammer and mechanical destruction of the piston group.
During the refueling process, the refrigerator must be turned off. Gas is introduced into the system, then the compressor is turned on for a short time (1-2 minutes) to distribute the gas, and turned off again to adjust the dose. The cycle is repeated until the nominal value is reached.
Operation control and sealing of the system
After the required amount of refrigerant is loaded, it is necessary to start the refrigerator in test mode. You need to monitor not only the temperature in the chambers, but also the temperature of the condenser (grid at the back) and the return tube. The condenser should be hot along its entire length (or 2/3), and the tube at the outlet of the evaporator (return) should be slightly warm or at room temperature.
If the return tube becomes covered with frost or “sweats” right up to the compressor, this is a sign of an excess of freon or a blockage. If the tube is dry and warm, and there is not enough cold, there is not enough freon. In the case of R600a due to the small amount of gas in the system (only 50-70 grams), an error of 10 grams is already critical.
The final stage is sealing. The Schrader service valve is clamped with a special clamp (pipe cutter-clamp) right at the base while the compressor is running (to create pressure in the tube). The tip of the tube is then sealed with a torch. The soldering area must be checked with a soap solution for bubbles.
⚠️ Attention: Do not use automotive sealants or “stop leaks” for refrigerators. These chemical additives contain substances that, after a few months, turn into acid and kill the compressor, and also clog the filter drier.
After making sure it is tight, wipe the soldering area and install the refrigerator in a permanent place. Full restoration of the temperature regime can take from 4 to 12 hours, depending on the volume of the chambers and the ambient temperature.
Frequently asked questions (FAQ)
Is it possible to fill a refrigerator with freon from an air conditioner can?
No, it is not possible. Car air conditioners use freon R134a, which is chemically similar to some refrigerator ones, but the oils and additives in them are different. In addition, the pressure and required purity of the substance in a domestic refrigerator are much higher. Using the wrong gas is guaranteed to disable the equipment.
How much does it cost to fill a refrigerator with freon yourself?
The cost consists of the price of the equipment (pump, station, burner - from 10,000 rubles, if you buy new) and the price of the gas itself (a R600a or R134a cylinder weighing 1-2 kg costs about 2000-4000 rub.). For a one-time refueling of one refrigerator, buying tools is not economically feasible; it is cheaper to call a specialist.
What to do if after refueling the refrigerator freezes but does not turn off?
This may indicate several problems: there is still a leak (poor soldering), a blockage in the capillary system, a malfunction of the thermostat or sensor, or an incorrect quantity Freon. It is necessary to check the compressor current and temperature in different parts of the circuit for diagnostics.
Is freon from an old refrigerator dangerous?
Old model freons (for example, R12) are not toxic in themselves in small doses, but they destroy the ozone layer. Modern freons (R600a) are explosive. Inhaling freon vapor in large quantities causes suffocation, as the gas displaces oxygen. Therefore, any work should be carried out in a ventilated area.