A sudden stop in the refrigerator compartment while the freezer is working properly often indicates a serious problem in the refrigerant circulation system. This condition, when capillary tube stops passing freon due to a blockage formed inside, is called “capillary blockage” in the professional environment. An independent solution to this problem requires not only specific tools, but also an understanding of the physics of the processes occurring inside a sealed circuit.
Before taking active steps, you must clearly understand that the system is charged refrigerant under pressure, and the entry of moisture or air into the circuit can completely remove the unit from building. In this article, we will look at how to diagnose the problem, what methods exist to fix it, and when you really need to call a specialist with a vacuum pump. Understanding these nuances will help you avoid fatal mistakes during repairs.
There is a common misconception that cleaning is possible without opening the system, but this is not the case. To access the problem area, a partial depressurization circuit will be required, which automatically implies subsequent evacuation and refilling with freon. If you are not ready for these procedures, further reading is for informational purposes only.
Diagnostics of capillary tube blockage
The first sign that capillary is clogged is the uncharacteristic behavior of the compressor. It can work continuously without turning off, trying to gain temperature, or it can turn on for a short time with a characteristic click and buzz, and then go into thermal protection. In this case, a complete absence of cold or, in rare cases, uneven cooling may be observed inside the chambers.
Visual inspection of the condenser grille (radiator) on the rear wall also gives important clues. In normal operation, it should heat up evenly over the entire area. If you observe that only the area next to the compressor is heating up, and the rest of the grille is cold, this is a sure sign that freon circulation is broken. Another method of checking is listening to the operation of the system. With the compressor running, listen for sounds coming from the evaporator area (usually the back wall inside the chamber or a hidden element). The absence of characteristic hissing or gurgling, which indicates gas flow, confirms the presence of a plug. freon circulation broken.
Another verification method is to listen to the operation of the system. With the compressor running, listen for sounds coming from the evaporator area (usually the back wall inside the chamber or a hidden element). The absence of a characteristic hissing or gurgling sound, which indicates gas flow, confirms the presence of a plug.
⚠️ Attention: If the compressor gets very hot (more than 90°C) and turns off after 1-2 minutes of operation, under no circumstances try to start it again immediately. Let it cool, otherwise the motor windings will burn out, and repairs will become economically unfeasible.
For accurate diagnostics, technicians often use the method of cutting off the tubes one by one. When the capillary tube is disconnected from the filter drier, gas under pressure should burst out with a characteristic whistle. If there is no gas outlet or it is barely noticeable, then the blockage is localized in this particular unit.
Causes of blockages and their types
Understanding the nature of the blockage is critical for choosing a method for eliminating it. Two main types of plugs can form in the refrigerator cooling system, each of which requires its own approach to elimination.
The first type is oil-paraffin blockage. It occurs due to the natural aging of the oil that circulates along with freon to lubricate the compressor. Over time, the oil oxidizes, thickens and precipitates, especially at the narrowest point of the system - the capillary tube. This process accelerates when the compressor overheats or the equipment is idle for long periods.
The second type is ice plug. It is formed due to the presence of moisture in the circuit. Water can get into the system due to poor-quality previous repairs, if the technician did not use a vacuum pump or broke the seal when filling. Passing through the capillary, where the temperature drops sharply, moisture freezes and blocks the passage.
There are also mechanical blockages caused by the ingress of decomposition products, metal shavings (when the compressor wears out) or flux residues after soldering into the system. Such cases are less common, but are the most difficult to eliminate.
It is important to note that the ice plug can sometimes be temporarily “broken” by heating, but without vacuuming the problem will return in a few days or weeks. An oil blockage often requires more radical measures, such as purging with nitrogen or completely replacing the capillary unit.
Necessary tools and preparation
Refrigerator repair is working with high pressures and chemically active substances. To perform the task efficiently, you will need a specialized set of tools, which are rarely found in everyday life.
The basic set of the master includes:
- 🔧 Turner (gas or oxygen-acetylene) for soldering copper tubes.
- 🌬️ Nitrogen cylinder and a reducer for purging the system and creating pressure.
- 🔌 Vacuum pump to remove moisture and air from the circuit.
- ⚖️ Scales for precise dosage of freon.
- 🔪 Pipe cutter and a rolling tool for working with copper.
You will also need consumables: new filter-drier (its replacement is required whenever the system is opened), solder and flux. Using an old filter is unacceptable, since its adsorbent is already saturated with moisture and will not be able to perform its function.
☑️ Preparation for repair
Without the presence of nitrogen and a vacuum pump, this repair cannot be undertaken sense. Attempts to clean the system “by eye” or by blowing with your mouth will only lead to moisture and oxygen entering, which will cause oil oxidation and the formation of acids inside the circuit.
Methods for cleaning the capillary system
There are several proven methods for removing blockages, the effectiveness of which depends on the type of plug and the equipment available. Let's consider them from the least labor-intensive to the more complex.
Warming and purging with nitrogen. This method is most effective against oil-paraffin plugs. The entry point of the capillary tube into the filter drier is heated red-hot by the burner. At the same time, nitrogen is supplied through the cut-off compressor tube at a pressure of 10-15 atmospheres. A sharp temperature change and high pressure knock out frozen paraffin.
Use of solvents. In some cases, technicians use special liquids to flush the refrigeration circuit (for example, R141b or specialized alcohols). The liquid is poured into the tube, left for a certain time to dissolve the deposits, and then blown out with nitrogen. This method requires extreme caution, since solvent residues can damage the insulation of the compressor windings.
Replacing a capillary tube. If cleaning does not produce results or the tube is damaged by corrosion, it is completely replaced. This is a complex process that requires the selection of a tube of a strictly defined length and diameter, since the pressure in the system depends on these parameters.
Why can’t you use oxygen for purging?
The use of oxygen or compressed air from a compressor for purging is strictly prohibited. Oxygen combines with compressor oil to form an explosive mixture. When heated by a burner, this can lead to a powerful bang inside the system and injury to the technician. Use only inert gases such as nitrogen.
It is worth remembering that after any of these procedures it is necessary to install a new filter drier. The old element will not be able to remove moisture, which will inevitably enter the system during repairs, and the ice plug will form again.
Step-by-step instructions for removing the blockage
The repair process requires a strict sequence of actions. Violation of technology at any stage can nullify all efforts.
1. Preparation and cutting. The refrigerator is disconnected from the network. Using a pipe cutter, the capillary tube is cut off at the entrance to the filter drier and at the exit from the evaporator. The compressor filling tube is also cut off.
2. Warming and purging. The burner heats the area where the capillary enters the evaporator and the filter itself. At the same time, nitrogen is supplied to the low pressure line. The pressure should be increased gradually, monitoring the integrity of the seams. If the blockage is oil, black slurry will come out of the tube.
3. Replacing the filter. The old filter drier is removed. The new filter is soldered into place. It is important to work quickly to minimize contact of the adsorbent with atmospheric air.
4. Evacuation. A vacuum pump is connected to the system. The process of pumping out air should last at least 30-40 minutes until a deep vacuum is achieved. This will remove all moisture from the system.
5. Refilling. After evacuation, the system is charged with freon strictly according to the scales, according to the passport data of the refrigerator model. Excess or lack of refrigerant is equally harmful to the operation of the unit.
Below is a table with typical parameters for different types of refrigerants that may be encountered during repairs:
| Refrigerant type | Pressure evaporation (bar) | Features | Cylinder marking color |
|---|---|---|---|
| R134a | 1.0 - 1.5 | Non-flammable, requires synthetic oil | Light blue |
| R600a | 0.5 - 0.8 | Explosive, requires mineral oil | Red |
| R12 | 1.5 - 2.0 | Outdated, prohibited for use | White |
Common errors and precautions
Independent repair of refrigerators involves risks. Most often, mistakes are made due to haste or lack of understanding of physical processes.
One of the main mistakes is insufficient vacuum. Many novice craftsmen believe that 10 minutes of pump operation is enough. However, moisture contained in the oil and on the walls of the tubes evaporates slowly. The remaining water will freeze in the capillary after a few days of operation.
Another mistake is using the wrong oil. Freon R134a requires polyester (synthetic) oil, which is hygroscopic (absorbs moisture). For R600a and R12 - mineral. Mixing oils or using the wrong type will result in the formation of a dense sediment and re-clogging.
⚠️ Warning: Freon R600a (isobutane), used in many modern refrigerators, is a flammable gas. All soldering work when using this refrigerant should be carried out only after complete evacuation of gas from the system and thorough ventilation of the room. A spark from a burner in a gas-filled room can cause an explosion.
It is also dangerous to exceed the pressure when purging with nitrogen. Copper tubes and an evaporator (especially aluminum) may not withstand pressure above 20-25 atmospheres, which will lead to rupture and the need for expensive replacement of components.
Frequently asked questions (FAQ)
Is it possible to clean the capillary without nitrogen and a vacuum pump?
Theoretically, you can try to blow out the system with your mouth or a can of water compressed air, but this will not give long-term results. You will not be able to remove moisture, which is the main cause of ice jams. Such a “repair” will extend the life of the refrigerator from several hours to a couple of days, after which the problem will return.
How much does it cost to replace a capillary tube in a service?
The price varies depending on the region and model of the refrigerator, but usually consists of the cost of work, a new filter, freon and a capillary tube. On average, this can range from 30% to 60% of the cost of a new budget refrigerator.
Why did the refrigerator start to freeze worse after cleaning?
Most likely, the dosage of freon was violated (underfilling or overfilling) or there was air left in the system. It is also possible that the compressor has lost performance due to wear and tear, and cleaning only exposed this problem. Repeated diagnostics using a pressure gauge station is required.
How often should the filter-drier be changed?
The filter-drier is a disposable element. It is changed every time the refrigerator circuit is opened (replacing a compressor, removing a blockage, a leak). Reusing an old filter is prohibited.
Can a capillary become clogged due to low-quality freon?
Yes, using cheap, unrefined freon with a high content of impurities and acids can lead to the rapid formation of deposits inside the system. Always use refrigerants from trusted brands in original containers.