Many owners of household appliances, faced with an increase in temperature in the refrigeration chamber, immediately wonder how to charge freon into the refrigerator with their by hand. Refilling refrigerant is a complex technological process that requires not only special equipment, but also a deep understanding of the principles of operation of a closed cooling cycle. Simply “topping up” gas like air into car tires will not work here due to the physical properties of the substances used.
Before considering the technical side of the issue, you need to clearly understand that R600a (isobutane) and R134a, which are most often used in modern models, they require pinpoint precision when dosing. Excess or deficiency the working substance in the system will lead to compressor failure or a complete lack of cold. In this article we will analyze in detail all the stages of professional refueling so that you understand the scale and complexity of the work.
It is worth noting right away that tightness of the circuit is the main condition for the longevity of the unit. If a leak occurs, then simply pumping gas without finding and eliminating the leak will only give a temporary effect. That is why the answer to the question “how is freon refilled” always begins with diagnostics and soldering, and not with connecting the cylinder.
Diagnostics of the system and search for leaks
The first stage of any repair related to the refrigerant is to identify the cause of it losses. Freon leak can occur in hidden places, for example, in the foamed part of the case or in the solder joints of the capacitor. The technician uses a leak detector or soap solution to visualize the gas exit. If the system is completely empty, this often indicates serious damage to the circuit.
During the diagnostic process, the integrity of compressor and filter driers is checked. Leaks often occur at the joints of metal tubes or in corrosion zones. To accurately determine the location of the defect, the system can be pumped with nitrogen under pressure to listen for a characteristic whistle or record a drop in readings on the pressure gauge.
⚠️ Attention: The use of open flame to search for leaks is strictly prohibited, especially if flammable isobutane could remain in the system. This may lead to an explosion.
Once a defect is detected, it is eliminated. If the evaporator tube is damaged, it is often necessary to replace the entire assembly or install an external shut-off valve. The quality of soldering seams is checked again with nitrogen pressure before starting the main work on evacuation.
It is important to understand that copper tubes they require careful handling. When heating with a torch, it is necessary to use flux and solder containing silver to ensure a reliable connection. A poorly soldered seam will become the site of a new leak after a few months of operation.
Necessary equipment and tools
To perform refrigerant recovery work, you will need a specialized set of tools, which are rarely found in everyday life. The main element is vacuum pumpnecessary to remove moisture and air from the system. Without deep evacuation, the residual moisture will turn into ice and clog the capillary tube.
Also gas station with a manometric manifold. It allows you to control suction and discharge pressure in real time. For accurate dosage of a substance, especially when refilling is carried out by weight, high-precision electronic scales with 1 gram increments are required.
The list of required equipment includes:
- 🔧 Gas burner with a set of nozzles for soldering copper tubes.
- 🌡️ Manometer (blue and red valves) for pressure control.
- 💨 Nitrogen cylinder for purging and pressure testing of the system before refueling.
- ⚖️ Electronic scales for weighing cylinder with freon during the injection process.
Special attention should be paid filter-drier. Whenever the system depressurizes, this element must be replaced, since it adsorbs moisture from the air and loses its properties. Using an old filter is a gross mistake leading to rapid breakdown.
The process of evacuation of the refrigeration circuit
Evacuation is a critical stage on which 90% of the success of the entire operation depends. Removing air and water vapor is necessary to prevent the formation of a so-called “air lock” in the system. It interferes with the normal circulation of the refrigerant and causes overheating of the compressor.
The process begins by connecting the vacuum pump to the service fitting. After turning on the equipment, gas pumping begins. The duration of the procedure depends on the power of the pump and the volume of the system, but usually ranges from 30 minutes to 1 hour. It is important to take your time so that the moisture has time to evaporate even from hard-to-reach places.
The quality of evacuation is monitored using a low pressure gauge. The arrow should go into the “green zone” and fix there. If, after turning off the pump, the pressure begins to increase, this indicates leakage of the system or the presence of moisture, which is actively evaporating.
| Parameter | Normal | Deviation | Consequence |
|---|---|---|---|
| Vacuum pressure | less than 0.1 mbar | Above 0.5 mbar | Residual moisture, ice plug |
| Pumping time | 30-60 min | Less than 15 min | Incomplete air removal |
| Stability | Arrow stands | The pressure is rising | Leakage or boiling of moisture |
After reaching the required vacuum, the valve is closed and the pump is turned off. The system should “stand” under vacuum for about 15-20 minutes to check for leaks. Only after making sure that the pressure does not rise, you can move on to the next stage.
Refrigerant charging technology
There are two main ways of introducing the working substance into the system: by weight and by pressure (current). Refilling by weight is considered the most accurate and professional. The nameplate (usually located inside the refrigerator) indicates the exact type and number of grams of refrigerant that needs to be pumped.
The process is as follows: a cylinder with freon is installed on the scale, the readings are recorded. The valve on the manifold opens and gas is supplied to the system. The operator monitors the change in the weight of the cylinder. As soon as the difference reaches the value specified in the instructions (for example, 130 grams), the supply stops.
☑️ Refilling algorithm by weight
If refueling is carried out by pressure, the technician is guided by the pressure gauge readings and the operation of the compressor. The suction pressure must correspond to the boiling point of freon in the evaporator. For R134a this is approximately 0.8-1.2 bar, and for R600a the pressure is lower and is often in the vacuum zone or near zero.
It is important to note that isobutane (R600a) is heavier than airso it accumulates at the bottom of the chamber, requiring special care when checking for leaks. When filling with this gas, the compressor is often turned on so that the gas is sucked through the nozzle, and not supplied under high pressure, in order to avoid water hammer.
After filling the system with gas, the service pipe is clamped with a special tube and sealed. This is the final stage of sealing. The soldering area must be checked with a soap solution for bubbles.
Operation control and testing
After completing the filling, it is necessary to start the refrigerator and monitor its operation for at least 30-40 minutes. The main indicator of correct freon dosage is the temperature of the compressor housing and the nature of its operation. It should not overheat (be hot, but not scalding) and should not work non-stop.
The technician checks the uniform cooling of the evaporator. A “snow coat” or frost should appear in the freezer over the entire surface, and not just at the entrance of the tube. In the refrigerator compartment, the temperature should drop to the set values (+4...+5°C).
⚠️ Attention: If after refueling the compressor runs continuously for more than an hour and the temperature does not drop, there may be air left in the system or the amount of refrigerant is incorrect.
The absence of vibrations is also checked and extraneous noise. Gurgling in the tubes is acceptable in the first minutes, but then the flow should become stable. The pressure on the pressure gauge (if it is connected for the test) should stabilize.
Why can’t you mix different types of freon?
Mixing different refrigerants (for example, R134a and R600a) leads to a change in the chemical and physical properties of the mixture. This can cause an explosive reaction, destruction of the compressor rubber seals and complete system inoperability. The mixture cannot be restored or adjusted correctly.
Typical errors and risks of self-repair
Attempts to perform filling the refrigerator on your own often end in failure of the equipment. The main mistake is ignoring the vacuum stage. An attempt to squeeze out air with freon itself (“blowing”) is ineffective, since freon is heavier than air and cannot completely displace it from the system.
Another common problem is excess of refrigerant. Beginners often pour gas “by eye,” which leads to the condenser filling with liquid freon. As a result, the compressor tries to compress the liquid, which leads to