A sudden cessation of refrigeration in the chamber, when the compressor continues to hum and the condenser remains cold, often indicates a critical violation of the refrigerant circulation. In most cases, the cause is a banal blockage of the capillary tube, which, due to its microscopic diameter, becomes clogged with oil breakdown products or oxides. Independent cleaning of this unit is a technically complex procedure that requires not only a special tool, but also an understanding of the principles of operation of the closed circuit of the refrigeration machine.
Before taking active steps, you must be clearly aware of the risks: breaking the tightness of the system without subsequent evacuation and refilling with freon will lead to the fact that the unit will stop freezing completely. However, if you have basic skills in working with copper pipes and are ready to strictly adhere to the technology, then it is quite possible to restore permeability capillary tube at home. This article will help you understand the causes of blockages and methods for eliminating them.
Diagnostics of blockages and signs of obstruction
The first symptom that is worth paying attention to is the abnormal behavior of the compressor and the temperature conditions inside the chambers. If the motor-compressor works almost non-stop, trying to gain temperature, but it is warm inside the refrigerator, and there are no characteristic heating and cooling zones on the rear grille (condenser), this is a sure sign that freon is not circulating. In its normal state, the condenser should be hot at the top and warm at the bottom, while with a clogged capillary it remains cold or barely warm along its entire length.
Another important indicator is listening to the operation of the system. When a working unit is turned on, a characteristic gurgling or hissing sound is heard, caused by the flow of liquid refrigerant through throttling device. If after startup there is dead silence, and after a while the protection relay clicks and the compressor stalls, it means that the discharge pressure has reached a critical point due to the inability to pump gas through the narrowed section. This condition requires immediate intervention.
To accurately localize the problem, technicians often use the method of feeling the filter-drier. In working condition, this element should be warm, but if the pipe entering it is hot, and the filter itself or the outlet from it is cold (sometimes even covered with frost), then the blockage is located precisely in the area of the capillary inlet or inside the filter itself. It is critically important not to confuse the blockage with a freon leak, since if there is a leak, the compressor, on the contrary, will be cold and work with overheating due to lack of cooling of the windings.
- 🔍 The compressor operates continuously, but is not turned off by the thermostat.
- 🌡️ The condenser (grid at the back) remains cold or at room temperature.
- 🔇 Absence of the characteristic sound of refrigerant circulation (gurgling) when running motor.
- ❄️ The appearance of local icing on the filter drier or at the capillary soldering point.
Necessary tools and workplace preparation
High-quality cleaning of the refrigeration system is impossible without specialized equipment, in particular, without a vacuum pump and manometric station. Attempts to blow through the system with your mouth or a bicycle pump will not yield results, since effective cleaning of moisture and small particles requires the creation of a deep vacuum, unattainable by household methods. You will also need a torch (gas or oxy-acetylene), a kit for soldering copper pipes with solder and flux, and a cylinder of dry nitrogen for purging.
Particular attention should be paid to preparing the workspace. All operations involving refrigerant and open flame should be carried out in a well-ventilated area, away from flammable objects. Since there may be residual freon in the system, when the pipes are heated, it can release toxic compounds, so the presence of forced ventilation or working in the open air are mandatory safety conditions. Also prepare a container with oil to check the compressor if you need to pump it separately.
The list of required tools includes a pipe cutter to avoid the formation of copper shavings inside the pipe, and a rolling machine if sections of the line need to be replaced. Using a hacksaw for metal is strictly prohibited, since the smallest chips that get into capillary tubewill instantly create a new, irremovable blockage, and the whole procedure will have to be started again. Save your nerves and time by using the right tool the first time.
⚠️ Attention! Before starting any work, be sure to disconnect the refrigerator from the electrical outlet. Working with electrical components and an open flame at the same time creates a risk of electric shock or fire.
Pressure nitrogen cleaning technology
The most effective and safe way to remove mechanical blockages is to flush the system with dry nitrogen. This inert gas does not react with oil and system components, and high pressure (usually from 10 to 15 atmospheres) allows you to dislodge the plug from oxides or paraffin. To implement this method, it is necessary to disconnect the capillary tube from the evaporator and the filter-drier, gaining access to both ends, and then connect the hose of the nitrogen cylinder to the entrance to the capillary.
The purging process requires caution: the gas supply should be carried out in short pulses so as not to damage the thin walls of the tube and not to create dangerous back pressure in other components. If the blockage is dense, you can gently heat the intended area (usually the entrance to the capillary or filter) with a burner while simultaneously applying nitrogen. Thermal expansion of copper and softening of wax deposits, combined with gas pressure, often work wonders in restoring permeability.
It is important to understand that after successful purging, the system remains open, and atmospheric air containing moisture inevitably enters. Therefore, immediately after restoration of patency, it is necessary to install a new filter-drier and carry out the vacuum procedure. Ignoring this step will lead to the fact that the moisture will freeze again in the capillary after a short time, forming an ice plug, and the refrigerator will stop working.
Why can’t you use oxygen for purging?
The use of pure oxygen or compressed air from a conventional compressor is strictly prohibited. Oxygen in combination with refrigeration oil at high pressure and temperature forms an explosive mixture, and the air from the compressor contains moisture, which will destroy the system from the inside.
Flushing the system and replacing the filter drier
If mechanical purging did not help or the nature of the blockage indicates the presence of acids and oil breakdown products (which often happens after combustion of the compressor windings), a complete flushing of the circuit is required. For this, a special solvent is used that is compatible with the system materials, for example R141b or specialized liquids. Washing is carried out by cyclically feeding a solvent through the system under pressure, followed by thorough drying with nitrogen.
An obligatory step for any intervention in a sealed circuit is replacing the filter-drier. This small element, filled with zeolite or molecular sieve, is responsible for absorbing moisture and acids circulating in the system. After opening the circuit, the sorbent in the filter is instantly saturated with moisture from the air and loses its properties, so reusing the old filter is unacceptable - it will become a source of problems in the near future.
When installing a new filter, it is important to observe time restrictions: after removal from the sealed package and until final soldering, no more than 15-20 minutes should pass. If you are late with soldering, it is better to throw away the old filter and get a new one, since its effectiveness is already in question. Soldering should be done quickly, using a damp rag to cool the filter housing so as not to overheat its contents.
| Type of blockage | Cause of occurrence | Remedy method | Need to change the oil |
|---|---|---|---|
| Mechanical | Copper shavings, dust, dirt | Nitrogen purge | No |
| Ice plug | Moisture in the system | Vacuum, filter replacement | No |
| Paraffin | Poor quality oil, oxidation | Warming up, washing | Desirable |
| Acid | Compressor combustion | Multiple flushing | Required |
Evacuation and refrigerant charging
After the permeability capillary tube has been restored and a new filter has been installed, the most critical stage begins - evacuation. This procedure is necessary to remove air and, most importantly, moisture from the system. Water boils at low pressure at room temperature, so creating a deep vacuum (about 300 microns) causes the moisture to evaporate and be removed by a pump. The duration of the process depends on the power of the pump and usually ranges from 30 minutes to 1 hour.
To refill with freon, it is necessary to use electronic scales, since the amount of refrigerant in modern refrigerators is measured in grams (usually from 30 to 150 grams). Overfilling or underfilling will lead to incorrect operation: in the first case, electricity consumption and the load on the compressor will increase, in the second, the unit will not freeze. The type of refrigerant (R134a, R600a) must strictly correspond to the marking on the refrigerator nameplate.
The charging process is best done with the compressor running, supplying gas in the liquid phase (by turning the cylinder over) or through the gas phase with control of the consumption current. After refueling, it is necessary to solder the filling pipe, check the tightness of the joints with a soap solution and make sure that the evaporator is cooled evenly. Only after this the system can be considered restored.
☑️ Checklist before starting
Typical errors and precautions
One of the most common mistakes is trying to clean the capillary with water or other active liquids without subsequent deep drying. The water that enters the system mixes with the oil and, when passing through the capillary, where the temperature drops, freezes, forming an ice plug. It is extremely difficult to expel this water back; it often requires repeated flushing with alcohol or a special solvent, which greatly complicates repairs.
Also, beginners often neglect to change the oil in the compressor when there is an acid blockage. If the cause is a winding breakdown, the oil turns into acid, which continues to corrode the insulation and metal parts even after cleaning. In such cases, simply replacing the compressor without flushing the entire circuit (evaporator and condenser) will lead to failure of the new motor in a few months.
Do not forget about fire safety when working with R600a (isobutane) refrigerant. This gas is explosive at a concentration in air of only 1.3%. Before carrying out soldering work on a system with R600a, you must ensure that all gas has been removed and flush the circuit with nitrogen. A spark from a soldering iron or static electricity can lead to serious consequences if gas remains in the tubes.
⚠️ Attention! If you feel unsure of your abilities or have no experience in soldering copper pipes, it is better to turn to professionals. The cost of clearing the blockage is often lower than buying a new refrigerator after a failed experiment.
Questions and answers (FAQ)
Is it possible to clean the capillary tube with a syringe with solvent?
Theoretically, you can try to force the solvent through the capillary using powerful syringe, but the effectiveness of this method is low. The pressure created manually is often not enough to break through a dense clog, and the volume of solvent is small to fully flush the entire system. In addition, in this way it is impossible to remove solvent and moisture from hard-to-reach places in the evaporator.
How to determine that the capillary is clogged with paraffin and not debris?
Paraffin clog is often of a “floating” nature: the refrigerator may periodically begin to freeze after a long period of storage (when the paraffin cools and shrinks), and then stop again. Mechanical blockage is usually permanent. An accurate diagnosis is made after opening the system and visually inspecting the contents of the filter.
Is it necessary to change the compressor if the capillary is clogged?
The clog itself does not require replacing the compressor if it is working properly. However, if the blockage is caused by combustion of the windings (acid attack), then the compressor is no longer faulty and requires replacement along with a complete revision of the system. In case of mechanical blockage or moisture, the motor can be left if it creates normal pressure.
How long does the cleaning and refueling procedure take?
For an experienced technician with ready-made equipment, the process takes from 1.5 to 3 hours, including time for vacuuming. At home, without experience and taking into account the search for tools, repairs can take a whole day. The main thing is not to rush with soldering and carefully monitor the tightness.