The situation when the refrigerator stops freezing, but the compressor runs non-stop, often indicates a refrigerant leak. Owners of household appliances who are faced with a similar problem often look for a way to restore the unit’s functionality on their own. However, the process filling the refrigerator with freon is technically complex and requires specialized equipment. Simply adding gas without evacuation of the system or using the wrong type of refrigerant can lead to irreversible damage to the compressor.
The main guideline for the master in the process of charging the system is pressure in the circuit. It is this parameter, along with the current consumption of the compressor electric motor, that allows you to determine the optimal amount of refrigerant. It is important to understand that pressure is an unstable value and directly depends on the ambient temperature and the type of gas used. Therefore, blindly following numbers from the Internet without taking into account temperature coefficients can be a fatal mistake.
In this article we will analyze in detail the technology for filling the refrigeration circuit, paying special attention to working with a pressure gauge station. You will learn how to properly prepare the system, what pressure standards exist for different brands of freon and why R600a requires more careful handling than R134a. Typical mistakes that beginners make when trying to carry out repairs with their own hands will also be considered.
Necessary tools and workplace preparation
Before starting any manipulations with the refrigeration circuit, you need to prepare a specialized tool. Without pressure station (manifold) it is impossible to carry out high-quality refueling, since it is impossible to visually determine the amount of gas in the system. The master's standard kit should include a vacuum pump, a scale for weighing the cylinder (although filling by pressure is the main topic, weight control is the best way to double-check) and a set of hoses of the appropriate diameter.
Particular attention should be paid to the tightness of the connections. Any microcrack in the hose or loose valve will allow air and moisture to enter the system, which will cause the formation of ice plugs or acidic compounds. To work with different types of freon, different hoses may be required, since the rubber structure differs in permeability for different gas molecules.
- 🔧 Manometric manifold with a set of hoses (blue, red, yellow).
- 🔧 Vacuum pump to remove air and moisture from the circuit.
- 🔧 Refrigerant cylinder of the appropriate brand (R134a, R600a or R12).
- 🔧 High-precision electronic scales (optional, for dual control).
- 🔧 Rolling tool and pipe cutter (if replacement of sections of the main line is required).
⚠️ Attention: Freon R600a (isobutane) is an explosive gas. All work with this refrigerant must be carried out in a well-ventilated area, away from open fire and sparking electrical appliances. A spark from a conventional switch can cause ignition.
Preparing your work area also means making sure there is good lighting and easy access to the back of the refrigerator. The compressor must be securely fastened, and all connections must be cleaned of dust and (oil contaminants) so that the oil leak that often accompanies a freon leak can be noticed in time.
Diagnostics of the system and detection of leaks
Refilling freon "by eye" or just "just in case" is categorically unacceptable. Before connecting the cylinder, you need to make sure that there are no leaks in the system, otherwise all the gas will leave in a few days or weeks. Primary diagnostics begin with a visual inspection of the pipes and soldering spots for oily stains. Oil is a companion of freon in a closed circuit, and where there is oil, there is a hole.
If visual inspection does not yield results, the system must be pressurized with nitrogen. This allows you to create excess pressure, which will help find even microscopic fistulas. The use of oxygen or ordinary air for pressure testing is prohibited, as this may lead to an explosion or oxidation of the internal parts of the compressor.
The process of finding a leak using a pressure gauge allows you to evaluate the tightness of the system over time. If the pressure drops, it is necessary. use a soap solution or an electronic leak detector to localize the problem. Only after eliminating all defects and soldering can you proceed to the next stage.
⚠️ Attention: Never try to find a leak with an open flame (lighter) in a system where gas could presumably remain. This can lead to an explosion or the formation of toxic phosgene when freon is burned.
The process of evacuation of the refrigeration circuit
Evacuating is a critical step that is often ignored by beginners, considering it a waste of time. However, nothing should remain in the system except pure freon. The air contains moisture, which freezes at low temperatures, forming an ice plug in the system. capillary tube. This blocks the circulation of the refrigerant, and the refrigerator stops cooling.
In addition, moisture reacts with oil and freon, forming acids that corrode the compressor windings from the inside. Vacuum pump allows the pressure in the system to be reduced to a minimum, which causes water to boil and evaporate even at room temperature. The duration of the process depends on the power of the pump and the volume of the system, but usually ranges from 15 to 30 minutes.
To connect the pump, use the yellow hose of the pressure gauge station. After connecting, you must open the valve on the manifold and start the pump. The arrow of the low pressure gauge (blue) should go into the negative zone. If the arrow does not drop or slowly returns up after. stopping the pump, this indicates a leak in the system.
☑️ Evacuation checklist
It is important to complete the process correctly: first close the valve on the manifold, and only then turn off the pump. If you do the opposite, oil from the pump can be drawn back into the refrigerator circuit, which will spoil the properties of the refrigerant.
Technology for charging freon using a pressure gauge
The most crucial point is direct filling the refrigerator with freonAfter evacuation, the refrigerant cylinder is placed on a scale (to control the quantity), and the yellow hose is connected to it a little before opening the valve on the cylinder. open it slightly to force the air out of the hose, and quickly close it.
Refilling is done through the service pipe, usually located on the compressor. Freon is supplied in small portions. First, the system is filled in the liquid phase (the container is upside down), but this must be done very carefully to prevent water hammer. compressor. It is better to add the main volume of gas in the vapor phase (cylinder up) while the compressor is running.
Pressure control is carried out using a low pressure gauge (blue). It is necessary to wait until the readings stabilize. The warmer it is, the higher the pressure. For example, at R134a at 25°C pressure is considered normal. 0.3–0.4 MPa (3–4 Bar), but the exact values must be checked with the table.
Why can’t you fill a full cylinder at once?
If you supply too much liquid freon into the system instantly, the compressor will try to compress the liquid, which will lead to mechanical destruction of the valves or even jamming of the piston group. This is called hydraulic. impact.
During the refueling process, it is necessary to constantly monitor the current consumption of the compressor using current clamps. If the current increases above the rated value indicated on the engine tag, it means that the system is overfilled, and some of the gas must be bleed. Overloading the compressor can cause it to overheat and burn out the windings.
Table pressure and temperature. dependencies
Understanding the relationship between pressure and temperature is the key to successful refueling. The boiling pressure of freon directly depends on its temperature. Below is a reference table for the most common refrigerants at +25°C ambient temperature. This data will help you navigate when setting up the system.
| Freon type | Pressure (Bar) at +25°C | Pressure (Bar) at +30°C | Features |
|---|---|---|---|
| R134a | 3.0 – 3.5 | 4.0 – 4.5 | Synthetic oil, requires good vacuum |
| R600a | 0.8 – 1.2 | 1.3 – 1.6 | Explosive, low operating pressure |
| R12 | 2.5 – 3.0 | 3.2 – 3.8 | Outdated, used in old equipment |
| R404a | 4.5 – 5.0 | 5.5 – 6.0 | High pressure, industrial refrigerators |
It is worth noting that the data in the table relevant for static pressure (when the compressor is turned off and the system is balanced) or for the initial phase. In dynamics, with the compressor running, the readings may differ. It is critically important to understand that suction (low) and discharge (high) pressures are different values, and the table usually refers to saturation pressure at a given temperature.
If the room is cold (for example, +15°C), then the pressure in the system will be lower. You should not try to “finish” freon up to summer standards in winter, this will lead to refilling. Always take into account the temperature coefficient.
Final check and sealing of the system
After achieving optimal pressure and current, it is necessary to correctly complete the procedure. The hose from the pressure gauge is quickly disconnected from the service pipe. At this moment, a small stream of gas may escape from the hole - this is normal, this forces the air out of the hose. The pipe on the compressor must be bent immediately (if it is a copper tube) or welded.
The most reliable method of sealing is soldering with silver-containing solder. The use of threaded valves (“shredders”) is allowed only as a temporary measure or in systems where periodic service refilling is provided, which is not typical for household refrigerators. The soldering area must be cleaned and treated with an anti-corrosion compound.
- 🧊 Check the uniformity of cooling of the evaporator (the entire evaporator should be cold).
- 🧊 Make sure there are no vibrations or extraneous noise from the compressor.
- 🧊 Check the temperature of the condenser (grid) back) - it should be warm.
- 🧊 Let the refrigerator run for several hours to stabilize the temperature.
⚠️ Attention: If after refilling the condenser (grid at the back) remains cold or warm only at the very beginning, and the evaporator does not freeze evenly, there may be an air lock in the system or the capillary tube is clogged with debris. Repeated diagnostics are required.
The final stage includes installing the refrigerator in place and loading it with food. It is not recommended to load the full volume of products at once - let the unit come into operation for 4-6 hours.
Frequent errors and precautions
One of the most A common mistake is to use freon that is not intended for this refrigerator model. Replacing R134a to R12 or vice versa without changing the oil and thoroughly flushing the system will lead to compressor failure. Oils for different freons have different chemical bases (mineral, polyolester) and may not mix, forming clots.
Ignoring the cleanliness of the instrument is also common. One drop of water or dust getting into the circuit can ruin the whole job. The filter drier, which is installed in front of the capillary tube, has a limited resource and, if the installation technology is not correct, may not cope with the volume of moisture.
Do not forget that modern refrigerators can be equipped with electronic control systems that block the start of the compressor if anomalies are detected in the operation of the sensors. In such cases, after mechanical repairs, you may need to reset errors through the service menu.
Is it possible to fill the refrigerator with freon yourself without equipment?
Absolutely not. Without a vacuum pump, you will not remove moisture, which will cause the capillary to freeze. Without a pressure gauge, you will not be able to control the process, which can lead to pipe rupture or compressor failure. This is not a case where you can get by with “folk methods.”
Which freon is better: R134a or R600a?
It is impossible to say that one is better than the other. R600a more environmentally friendly and economical, but explosive. R134a safer in terms of combustion, but requires higher pressure and is sensitive to moisture. You need to refill strictly with the type indicated on the nameplate of your refrigerator.
Why does the refrigerator freeze after refilling, but does not turn off?
Most likely, freon was underfilled or air remained in the system. The cause may also be a leak in the circuit (the gas left after a week) or a malfunction of the thermostat. If the compressor is running around the clock, this is an alarming signal.
Is it necessary to change the oil in the compressor when refueling?
During normal refueling, after eliminating the leak, the oil does not need to be changed if it has not lost its properties (has not turned black, has not become viscous). The oil changes only when the compressor burns out or when switching to another type of freon, which requires a different chemical base of the oil.