A decrease in cooling efficiency or a complete stop of the refrigerator Ariston often indicates a critical blockage in the refrigerant circulation system. The capillary tube, which has an extremely small internal diameter, is the most vulnerable element, where moisture or oil breakdown products turn into an ice or hard plug. Without timely intervention, the compressor begins to work with overload, and the chamber stops freezing, which requires immediate technical intervention.
Restoring the patency of the main line is a complex process that requires not only specialized equipment, but also a deep understanding of the physics of the refrigeration circuit. In this article, we will analyze in detail the methods for determining the localization of a blockage, the technology of purging with highly pressed nitrogen and the nuances of replacing the filter-drier, without which high-quality repairs are impossible.
The principle of operation and the reasons for capillary clogging
The capillary tube in the refrigeration unit performs the function of a choke, creating the necessary vacuum before evaporator. It is here that a sharp drop in the pressure of liquid freon occurs, which leads to its active boiling and absorption of heat from the refrigerator chambers Ariston. The length of this element can reach several meters, and the diameter is a fraction of a millimeter, which makes the system sensitive to any foreign inclusions.
The main cause of obstruction is most often moisture that got into the circuit due to poor-quality previous repairs or leakage. Interacting with the refrigerant and oil, water forms acidic compounds that corrode metals and create solid deposits. Ice plug forms at the narrowest point of the capillary, completely blocking the freon flow and stopping the cooling cycle.
The second common reason is Compressor engine oil degradation. During prolonged operation or overheating of the unit, the oil loses its properties, oxidizes and precipitates in the form of paraffin or resinous deposits. These substances gradually accumulate, narrowing the flow area of the tube to a critical minimum, which is especially typical for older models of refrigerators.
⚠️ Attention: An attempt to start a refrigerator with a clogged capillary without eliminating the cause will lead to overheating of the compressor and its eventual failure due to operation on a vacuum or excessive back pressure.
Diagnostics of the system condition requires a careful analysis of symptoms. If you notice that the condenser (grid at the back) heats up unevenly or only in the upper part, and the temperature in the refrigerator compartment is higher than normal, this is a sure sign of a circulation problem. Also an alarming factor is the intermittent operation of the engine with frequent stops.
Diagnostics and localization of the blockage
Before taking active cleaning actions, it is necessary to accurately determine the location and nature of the blockage. Professional craftsmen use the method of alternately cutting off sections of the system and monitoring the pressure with a pressure gauge station. To begin with, the refrigerator Ariston is disconnected from the network, and the refrigerant is taken out through a puncture of the process pipe.
After evacuating the system and filling it with nitrogen under pressure up to 10-12 atmospheres, the technician listens to the noise. If, after turning off the compressor, the hissing of gas stops instantly, it means that the permeability of the capillary tube is impaired. Localization is narrowed by unsoldering the filter-drier: if, when opening the circuit from the condenser side, a strong whistle of the escaping gas is heard, it means that the filter itself or the entrance to the capillary is clogged.
For a more accurate determination, use the method of purging individual sections. Having disconnected the capillary from the evaporator, check whether it can be blown through the mouth or a compressor (with caution). Resistance to air flow should be noticeable, but uniform. If the air does not pass at all or passes with difficulty only after strong pressure, a complete or partial blockage is diagnosed.
It is important to distinguish between an ice plug and a mud plug. Ice is often temporary and can thaw during prolonged inactivity, but when restarted it forms again due to residual moisture. The dirt plug is stable and requires mechanical or chemical cleaning of the entire line.
Necessary tools and workplace preparation
High-quality cleaning of the capillary tube is impossible without specialized equipment. Amateur methods such as blowing with your mouth or using car tire compressors will not provide the necessary pressure and can drive moisture even deeper into the system. You will need a professional kit for working with refrigeration equipment.
The key element is a dry nitrogen cylinder equipped with a reducer. It is nitrogen that is used for purging, since it is inert, does not support combustion and, most importantly, does not contain moisture, unlike compressed air. The pressure during purging can reach 30 atmospheres, so all connections must be tight and reliable.
- 🛠️ Manometric station with a set of hoses for monitoring the pressure in the system.
- 🔥 Gas burner with solder for soldering copper tubes and replacing the filter.
- 💨 A cylinder with dry nitrogen and a reducer to create high pressure when purging.
- 🧪 New filter drier that matches the model of your refrigerator Ariston.
- 🔪 Pipe cutter and roller for preparing the ends of copper tubes.
It is also necessary to prepare a container to collect old oil that may leave the system during purging. The workplace must be well ventilated, since when copper pipes are heated, oil residues may burn out and form an unpleasant odor. Don't forget about personal protective equipment: gloves and goggles.
☑️ Preparing to repair the refrigerator
Technology for purging the capillary tube with nitrogen
The cleaning process begins with depressurization contour. After releasing the residual refrigerant pressure, it is necessary to unsolder the filter drier on the condenser side. This is a critical moment, since it is the filter that often takes the brunt of contaminants. The old filter is disposed of, a new one is not installed yet.
Next, a hose from a nitrogen cylinder is connected to the free end of the condenser through a reducer. The pressure is gradually raised to 10-15 atmospheres. If patency is maintained, you will hear the characteristic noise of passing gas. If the blockage is complete, the pressure on the pressure gauge will increase, but gas will not escape. At this point, you can try to briefly increase the pressure to 20-25 atmospheres, but with caution so as not to damage the solder.
If the blockage is located deep in the capillary, the “backwash” method is used. Nitrogen is supplied from the evaporator side (after disconnecting the capillary from it) towards the compressor. This allows the plug to be pushed to the side where there is least resistance, often directly into the process connection or through a disconnected filter. Countercurrent Blowing Particularly effective for removing oil plugs.
⚠️ Attention: When backflushing through the compressor, make sure that the suction pipe not directed at the face, since a stream of old oil and dirt can fly out along with the air.
In particularly difficult cases, when nitrogen cannot cope, craftsmen use special solvents, pouring them into the tube and leaving them for several hours to soften the resinous deposits. However, this method is risky, as it requires perfect subsequent flushing and vacuuming, otherwise the chemistry will destroy the system from the inside.
Can compressed air be used?
Using conventional compressed air from a compressor is highly not recommended. The air always contains moisture, which, if it enters the system, will freeze again in the capillary, exacerbating the problem. In addition, oil from the tire inflation compressor can contaminate the circuit even more. Only dry nitrogen!>
Replacing the filter-drier and assembling the system
Successfully cleaning the capillary tube does not make sense without replacing the filter-drier. This element is responsible for retaining microscopic particles of moisture and dirt. The old filter is already saturated with moisture and is not able to perform its functions, so reusing it or trying to “calcinate” it is pointless and will lead to a relapse in a short time.
The new filter is selected strictly according to the parameters of the refrigerator Ariston: the outer diameter of the tubes, the type of refrigerant (R134a, R600a) and overall dimensions. Installation is carried out quickly to minimize contact of the filter interior with atmospheric air. Before soldering, the ends of the copper tubes are stripped and inserted into the filter until they stop.
| Refrigerant type | Tube diameter (mm) | Compatibility | Soldering features |
|---|---|---|---|
| R134a | 6 / 8 | Most Ariston models | Requires quick soldering |
| R600a | 6 / 6 | Modern models | Caution with open flame |
| R12 (old) | 8 / 8 | Vintage models | Can be replaced with a universal one |
| Universal | 6 / 8 | Selected according to location | Requires adapters |
The filter must be soldered carefully, without overheating, so as not to melt the solder inside the filter itself or burn through the thin wall of the tube. After installing the filter, the system is assembled to its original state: the process pipe with the Schrader valve is sealed for subsequent charging.
Evacuation and charging with refrigerant
The final and most important stage is the removal of air and moisture from the system. Even after purging with nitrogen, microscopic residues of moisture remain in the tubes, which at low temperatures will turn into ice. For this, a vacuum pump is used, connected to the process pipe.
The vacuum process should last at least 30-40 minutes. The pressure in the system should drop to a deep vacuum (about -1 atm or lower, depending on the gauge scale). Only after this the station valve is closed and the pump is turned off. If the pressure gauge needle begins to creep up, it means that there is a leak in the system, and the procedure must be repeated after searching for the leak.
Refrigerant charging is carried out strictly according to the weight indicated on the refrigerator label Ariston. A lack of freon will lead to poor cooling, and an excess will lead to increased pressure in the system and possible rupture of tubes or compressor failure. Refueling is monitored using a low pressure gauge and compressor current consumption.
⚠️ Attention: The exact weight of the refill is critically important. Using pressure and temperature correspondence tables without scales does not guarantee correct operation of the system, since the pressure depends on the ambient temperature.
After refueling, the refrigerator is plugged in and its operation is checked for several hours. The uniformity of cooling of the condenser, the temperature in the chambers and the absence of extraneous noise are assessed. If all parameters are normal, the process pipe is finally sealed.
Common mistakes during self-repair
Independent repair of refrigerators often ends in failure due to neglect of technological nuances. One of the most common mistakes is neglecting to replace the filter drier. Amateur craftsmen often limit themselves to blowing, believing that they have removed all the debris, but the filter remains wet and continues to release moisture into the system.
Another mistake is using an open flame near gas cylinders or when working with R600a (isobutane) refrigerant, which is flammable. Although the gas is usually released at the time of soldering, residues in the oil can ignite. Safety Should be the number one priority when working with flammable substances and high pressure.
Insufficient vacuum time is also common. Ten minutes of pump operation is not enough to evaporate all the moisture from the complex labyrinths of the capillary tube and evaporator. The moisture remains in the form of steam and condenses only during the first freezing cycle, recreating the ice plug.
Do not forget about the quality of soldering. Using the wrong solder or flux can lead to the formation of oxides inside the tube, which will become a new blockage after six months. Acid fluxes are strictly prohibited for refrigeration systems, as they cause corrosion of copper from the inside.
Is it possible to clean the capillary without removing the compressor?
In most cases, cleaning is done without dismantling the compressor, by cutting off the filter and blowing in both directions. However, if the blockage is caused by decay products of the compressor oil itself or metal shavings, it may be necessary to flush the entire system, which sometimes involves temporary removal of the unit for high-quality treatment with solvents.
How much does it cost to replace a capillary tube during service?
The cost depends on the model of the refrigerator Ariston and the difficulty of accessing the evaporator. If the tube is foamed into the body, the work of replacing it (opening, welding a new one, foaming) will cost much more than simply blowing out the existing line.
Why does the refrigerator freeze after blowing, but turns off?
This may indicate that the blockage has been partially removed, or there is air left in the system, which creates an air leak traffic jam Also, the reason may be a faulty thermostat or start relay, which could suffer from power surges while the compressor is operating with a clogged system.
How long does the capillary tube last after cleaning?
Provided that the system is completely sealed, the filter is replaced and properly refilled, the service life of the capillary is not limited. Re-clogging is possible only if the circuit is depressurized or low-quality oil/refrigerant is used during repairs.