The situation when the refrigerator compressor runs continuously, hums, but there is heat inside the chambers, often confuses the owner. In most cases, especially when it comes to older models or units after defrosting, the culprit becomes clogged capillary tube. This is a narrow line through which the refrigerant passes from high pressure to low, and even a microscopic particle of oxide or moisture can stop the circulation of freon.
You can diagnose the problem at home by characteristic signs: the condenser (grid at the back) remains cold or warm only at the outlet of the compressor, and the evaporator inside the chamber is not evenly covered with frost. An attempt to solve the problem by simply defrosting for 24 hours helps only in the case of an ice jam, but if the ice is caused by oil or decomposition products, a system is required. mechanical cleaning systems.
Before taking active steps, you must understand that working with the refrigeration circuit requires care and the presence of specific The tool Capillary tube has an internal diameter of less than a millimeter, and improper handling can lead to its deformation or complete failure. In this article we will look at proven methods for restoring patency, which are used by professional craftsmen.
Causes of blockages in the capillary system
Understanding the nature of the blockage is half the success of the repair. Most often, copper oxidation products enter the system, which are formed when oil and freon come into contact with residual moisture or oxygen. Also, the cause may be hydraulic hammeroccurred due to improper refueling, or simply aging of the compressor oil, which loses its properties and precipitates.
Moisture is a particular danger. If there is air left in the system or a low-quality refrigerant is used, water freezes in a narrow section of the capillary, forming an ice plug. Unlike mechanical debris, such a blockage can be temporary: after the compressor stops, the ice melts and the refrigerator begins to freeze again for a short time, creating the illusion of serviceability.
- 🧪 Moisture entering the circuit due to poor vacuuming.
- 🛢️ Engine oil decomposition products and oxides copper.
- 🔩 Mechanical shavings or solder remaining after a previous repair.
⚠️ Attention: The use of open fire to warm up the tubes without bleeding freon is strictly prohibited. Refrigerant vapors are toxic and, upon contact with fire, can form phosgene, a chemical warfare agent.
Sometimes the blockage is localized not in the twisted tube itself, but in inlet or in the filter-drier. The filter is designed to trap moisture and debris, but over time its capacity is exhausted, and it itself becomes an obstacle to the flow of refrigerant. In such cases, simple purging may not provide a long-term effect without replacing this element.
Necessary tools and consumables
For high-quality cleaning of the capillary, it is not enough to have only a screwdriver and pliers on hand. You will need to pressurize the system well above atmospheric pressure to pop the plug. The main tool here is a cylinder with dry nitrogenequipped with a reducer capable of regulating pressure up to 10-15 atmospheres.
If nitrogen is not available, experienced craftsmen sometimes use a compressor, but here lies the risk of introducing moisture and oil into the circuit. You will also need a torch (gas or oxy-acetylene), copper solder, flux and, of course, a new filter drier. Without replacing the filter, re-clogging will occur with a 90% probability within a month.
To flush the system from oil deposits, you will need a special one solvent. In a professional environment, R11 or specialized liquids are used, but at home, purified Galosh gasoline or alcohol are often used. It is important that the liquid is absolutely dry and does not leave greasy marks after evaporation.
Method of purging with nitrogen under pressure
The most effective and safest method for internal components is purging the circuit with nitrogen. First you need to get to the capillary tube, which is usually soldered into the evaporator or glued to it. The tube is carefully unsoldered from the filter-drier, freeing the entrance to the capillary.
Next, a hose from a nitrogen cylinder is connected to the free end of the capillary (via an adapter). The pressure is raised gradually, starting from 2-3 atmospheres, and the air outlet from the other side is controlled. If the capillary is clogged “tightly”, the pressure can be briefly increased to 10-12 atmospheres, but no more, so as not to rupture the thin walls of the tube.
Sequence of actions:1. Unsolder the capillary from the filter.
2. Connect the nitrogen gun.
3. Apply pressure 2-5 atm.
4. Monitor the blowing at the outlet.
If the blockage was broken through, you will hear a characteristic whistle of escaping gas. However, simply purging the system is not enough. Along with the gas flow, only large debris will come out of the tube, and oily deposits will remain on the walls. Therefore, the procedure is often combined with chemical washing.
☑️ Checking readiness for purging
Flush the system with a solvent
Chemical flushing is necessary when the blockage is caused by thickened oil or waxing. The solvent is poured directly into the capillary tube or supplied under pressure if a special installation is used. The liquid dissolves oil deposits and washes them out of the bends of the tube.
The process is as follows: about 10-15 ml of solvent is poured into a sealed capillary tube through a funnel or syringe. The system is then left to react for a few minutes. After this, intensive nitrogen purging is carried out to remove dissolved dirt and remnants of the chemical itself.
After washing, the capillary must be absolutely dry. To speed up the drying process, you can blow the system with warm air (but not hot air, so as not to damage the insulation), but nitrogen is preferable since it is inert and dry.
⚠️ Attention: Never use water or alcohol-containing liquids with a high water content for flushing. Residual moisture in the system will lead to the formation of acid when mixed with oil, which will destroy the compressor winding.
What are the dangers of using acetone?
Acetone is an aggressive solvent that can damage the insulation of the wires inside the motor-compressor if it gets into the housing. In addition, acetone is hygroscopic and can introduce excess moisture into the system, which is unacceptable.
Replacing the filter-drier and vacuuming
Any manipulation with depressurization of the circuit requires a mandatory replacement of the filter-drier. This small cylinder, located between the condenser and the capillary, contains zeolite, a substance that absorbs moisture. Upon contact with atmospheric air, the zeolite is instantly saturated with moisture and stops working.
The replacement process is simple: the old filter is cut off or soldered off, and a new one is installed in its place. It is important to do this quickly to minimize the time the exposed tubes are exposed to air. After installing a new filter and sealing all connections, the system must be evacuated.
Evacuation removes air and moisture vapor from the circuit. For this purpose, a vacuum pump connected to the service connection is used. The process lasts at least 15-20 minutes. The residual pressure should be about 30-50 microns (or the maximum possible for a household pump). Only after creating a deep vacuum can refilling with freon be carried out.
| Work stage | Necessary equipment | Critical parameters |
|---|---|---|
| Purge | Nitrogen cylinder, reducer | Pressure up to 10-12 atm |
| Rinsing | Solvent, syringe/funnel | Complete removal of chemicals |
| Vacuuming | Vacuum pump, pressure gauge | Residual pressure < 500 microns |
| Refilling | Scales, freon cylinder | Weight according to passport (± 5 d) |
Common mistakes during self-repair
One of the most common mistakes is an attempt to clean the capillary by simply “pumping” the system with a running compressor. This leads to overheating of the motor, since it operates without heat removal by the refrigerant, and often ends compressor wedge or winding breakdown. In addition, in this way it is impossible to create the necessary pressure to break through a serious blockage.
Another mistake is ignoring filter replacement. Even if you managed to clean the tube, the old filter will immediately release accumulated moisture back into the system. The result will be re-freezing of the capillary after a few hours or days of operation of the refrigerator.
Also, do not neglect the quality of the soldering. Using too much solder can cause it to flow into the tube, creating a new, artificial clog. The seam must be neat, and excess solder must be removed.
Is it possible to clean the capillary without a nitrogen cylinder?
Theoretically, you can use a powerful bicycle pump or compressor, but the efficiency will be low. A pressure of 2-3 atmospheres rarely breaks through a dense oil blockage. In addition, the compressor forces moisture and oil into the system, which aggravates the situation. It is better to use the services of a service center where nitrogen is available.
How much does it cost to clean the capillary in the service?
The price depends on the model of the refrigerator and the type of refrigerant. On average, the work of a master, taking into account materials (nitrogen, filter, freon, soldering) ranges from 3,000 to 6,000 rubles. Self-repair is cheaper, but requires the purchase of equipment (burner, pump, cylinders), which can cost more than one service.
Why does the refrigerator freeze poorly after cleaning?
Perhaps there is moisture left in the system that has frozen in the capillary, or the blockage has not been completely removed. Also, the cause may be improper refilling of freon (underfilling or overfilling) or the presence of air in the circuit due to poor evacuation.
Is it necessary to change the compressor oil when cleaning?
When simply cleaning the capillary, the oil in the compressor is not changed, unless the system has been completely flushed with a large volume of solvent. In the standard procedure for purging and replacing the filter, old oil remains in the compressor crankcase.