Failure of the refrigerant circulation system often leads to the fact that the refrigerator stops freezing, although the compressor continues to hum. In such cases, technicians often diagnose a blockage or mechanical damage capillary tube, which is the “artery” of the entire cooling system. Replacing this element is not an easy task, requiring special tools and skills, but theoretically feasible for an experienced home craftsman.
The process of restoring the functionality of the unit Indesit or Atlant begins with an understanding of the operating principle. The refrigerant passes through a long thin copper coil where a sudden drop in pressure and temperature occurs. If this path is blocked by ice, debris or oxides, circulation stops. When replacing the capillary tube, it is critical to maintain the exact length and diameter of the new part, since the pressure in the system and the efficiency of the compressor depend on this.
Before proceeding with dismantling, it is necessary to empty the refrigerator of food and disconnect it from the power supply. You will need time to prepare the workplace, as the procedure will take several hours. You should not expect an instant result; haste in this matter is the main enemy of the quality of the repair.
Fault diagnosis and preparation
The first sign of problems with the capillary system is often uneven cooling of the chambers. The evaporator may be only partially covered with frost, or gurgling can be heard in the system, followed by complete silence. In some cases, swelling can be seen on the back side of the condenser, which indicates high pressure due to obstruction of the line.
To accurately determine the diagnosis, it is necessary to palpate the tubes of the operating compressor. If the discharge pipe is hot and the return pipe is cold or at room temperature, this is a sure sign of a blockage. It is also worth paying attention to filter drier: if it is icy to the touch, it means that moisture or dirt has blocked the passage of the refrigerant.
Preparation for repair includes unsoldering old connections and draining residual oil from the compressor. This must be done carefully so as not to damage other components of the unit Bosch or Liebherr. Be sure to prepare a container for used oil, as it may contain acidic impurities.
⚠️ Attention: Before starting work, make sure that there is no open fire in the room. The refrigerant leaving the system can be flammable or toxic depending on the type of freon (R134a, R600a).
Necessary tools and materials
High-quality repairs are impossible without specialized equipment. You will need a gas torch with a solder kit, a pipe cutter, a flange and, most importantly, a vacuum pump with a pressure gauge station. Without the latter device, it will not be possible to replace the capillary tube correctly, since the system must be perfectly sealed and dry.
It is important to purchase a new capillary in advance, which in its characteristics matches your compressor. Parameters internal diameter and lengths must match the original. You will also need new fittings, solder (silver or copper-phosphorus) and, of course, a new filter drier, which is changed every time the system is depressurized.
Remember to have a rag and solvent ready to clean the soldering areas. Copper oxides can cause re-clogging if not removed thoroughly. You should work in a well-ventilated area, using personal respiratory protection.
Removing the old capillary and washing
The process begins with carefully unsoldering the capillary tube from the filter-drier and evaporator. Heat the connection evenly with a torch, avoiding overheating of adjacent plastic parts of the housing. After depressurization, the old capillary is removed, often along with the heat exchanger if it is glued to the back wall.
Particular attention should be paid to flushing the system. If the cause of the breakdown was combustion of the compressor winding, acid could remain inside. Flushing is carried out with nitrogen under pressure or special solvents, blowing the circuit in both directions. This will remove residual oil and mechanical inclusions.
During dismantling it often turns out that the old capillary was damaged by corrosion. In this case, it is necessary to clean the attachment points of the new element. For models Stinol or Nord the tube is typically adjacent to the back wall, which will need to be carefully separated without damaging the insulation.
☑️ Preparation for soldering
Installing a new tube and soldering
Installation of a new element requires precision. The capillary tube must be laid along the contour of the old one, observing the bend radii. Sharp creases are unacceptable, as they will cut off the freon flow. Fixation is done with aluminum pads or heat-resistant glue, depending on the design of the evaporator.
Soldering of connections is carried out using flux, but its amount should be minimal. When heated, excess flux can get inside the tube and cause a new blockage. First, the connection to the filter drier is soldered, then to the evaporator. It is important not to overheat the filter itself by holding it with a damp cloth.
To ensure proper operation, it is often necessary to solder an additional section of copper tube (crimping) between the capillary and the filter. The length of this section is selected experimentally or according to factory specifications. This helps stabilize the refrigerant flow and reduce noise.
| Parameter | Value / Description | Impact on operation |
|---|---|---|
| Capillary diameter | 0.6 - 0.9 mm | Determines the throughput |
| Tube length | 2.5 - 4.5 meters | Influences condensation pressure |
| Soldering temperature | 600 - 750 °C | Necessary for solder spreading |
| Nitrogen pressure | 10-15 bar | Used for purging |
⚠️ Attention: The filter drier cannot be kept open in the air for more than 15 minutes. It instantly absorbs moisture, which will lead to the formation of an ice plug in the system a few days after startup.
Evacuation and refrigerant charging
After soldering all connections, the most critical stage begins - evacuation. A vacuum pump is connected to the service fitting, which should run for at least 30-40 minutes. The purpose of the process is to remove air and water vapor from the circuit, which would boil at low temperatures, disrupting the operation of the refrigerator.
Evacuation quality control is carried out using a low pressure gauge. The needle should go to the “green zone” (below zero) and remain stable there after the pump is turned off. If the pressure begins to increase, it means that there is a leak in the system that needs to be found and eliminated.
Refilling is done strictly by scale, using the data from the nameplate on the refrigerator body. An excess or lack of freon is equally harmful to compressor. The refrigerant is introduced into the operating system (with the compressor turned on) through the low pressure fitting in a gaseous state.
Why can’t you fill with liquid freon?
Filling with liquid freon into the compressor can cause a hydraulic shock that will instantly destroy the valves or piston group of the motor. Always evaporate freon before entering the compressor.
Typical replacement errors
One of the most common mistakes is using a capillary tube of the wrong length. Even a slight deviation can cause the refrigerator to either “underfreeze” or work with overload. In the case of models Samsung or LG this often causes sensor error and protection.
Another common problem is poor soldering. If the solder has not flowed on all sides or a void has formed, freon leakage will occur after several months of vibration. It is also dangerous to use a large amount of flux, which turns into solid coke deposits inside a narrow tube.
Some craftsmen forget to purge the system with nitrogen before soldering. Copper oxides formed during heating without gas protection will inevitably enter the new capillary. This will lead to repeated repairs as soon as possible, since the system will be clogged again.
Checking tightness and starting
The final stage is checking the assembled system under pressure. After filling with freon, all connections are generously lubricated with soap solution. The appearance of bubbles will indicate the location of the leak. If everything is clean, the refrigerator is turned on and monitored for several hours.
Normal operation is characterized by uniform heating of the condenser (grid at the back) and cooling of the evaporator inside the chamber. The temperature should rise smoothly. If the compressor works without stopping and does not turn off by the thermostat, the amount of freon may be selected incorrectly.
During operation, unstable operation may be observed in the first day. This is due to the system reaching operating mode and oil distribution. However, if the freezer does not reach temperature in 5-6 hours, the procedure will probably have to be repeated.
Is it possible to replace the capillary tube without a vacuum pump?
Theoretically, there are methods of “displacing” air with freon, but they are extremely ineffective and do not guarantee the removal of moisture. Without a vacuum pump, there is a high risk of ice blockage forming in the filter after a week of operation. Professional repairs require vacuuming.
Which solder is best to use for soldering?
For copper-copper connections, copper-phosphorus solder without flux is optimal. If you are soldering copper to steel (for example, a discharge tube), you definitely need silver solder with a silver content of at least 15-20% and an appropriate flux.
Why does the refrigerator hum loudly after replacing the capillary?
Extraneous sounds may indicate liquid (oil or freon) getting into the compressor cylinder, which often happens when refueling is incorrect. Also, the cause may be vibration of an incorrectly secured new tube against the housing or cabinet walls.
Does it need to be replaced if the capillary is clogged?
Not always. If the blockage is caused by oxides or moisture, the compressor can be left. But if the cause is a winding breakdown and oil burning (acid background), then replacing the compressor is mandatory, otherwise the new capillary will also quickly fail.