The situation when the refrigerator stops freezing, but the compressor continues to work, is familiar to many owners of household appliances. Often the cause of such a breakdown is clogging in the capillary tube, which disrupts the normal circulation of the refrigerant. The capillary tube, which has an extremely small internal diameter, is the most vulnerable section of the freon line, where any foreign particles or moisture can lead to a complete stop of cooling.
Eliminating this malfunction requires the master not only theoretical knowledge, but also practical skills in working with vacuum pumps and burners. Unlike replacing a thermostat or start relay, dealing with a blockage involves the risk of damaging the thin walls of the tube or breaking the tightness of the entire system. That is why it is important to clearly understand the nature of the blockage and choose the right method for restoring patency.
In this article we will analyze in detail the types of blockages, tools for eliminating them and a step-by-step algorithm of actions. You will learn how to distinguish an ice plug from an oil plug, what cleaning methods exist, and when it is better to replace the entire part. Correct diagnostics at the initial stage will allow you to avoid unnecessary costs and repeated breakdowns.
Causes of blockage of the capillary system
The main cause of blockages is a violation of production technology or poor-quality repairs in the past. If moisture gets into the circuit during assembly of the refrigeration unit, it will inevitably lead to the formation of hydrate plugs. Water, mixing with oil and refrigerant, freezes at subzero temperatures, blocking the narrow passage of the tube, the diameter of which is less than one millimeter.
Another common cause is oxidation of the inner walls of copper tubes or decomposition of motor oil. Over time, hard, tarry deposits form in the system and accumulate in areas of constriction. This happens especially often in models where mineral oil, incompatible with modern refrigerants, was used, or when the compressor overheated.
⚠️ Attention: Moisture entering the system often occurs due to a violation of the tightness during soldering or the use of low-quality freon mixed with air. Oxygen and water are the main enemies of the refrigeration circuit.
It is also worth mentioning mechanical impurities, such as copper shavings or decomposition products of the filter drier. If the filter drier has expired or was selected incorrectly, its filler may spill out and clog the capillary. In rare cases, the blockage is caused by the polymerization of the oil, which turns the liquid into a viscous mass that blocks the flow of the refrigerant.
Diagnostics: how to determine the type of blockage
Before starting any work to restore patency, it is necessary to accurately determine the nature of the malfunction. Primary diagnosis is carried out visually and auditorily. If you hear that the compressor is humming, but the refrigerator is not cooling, and the condenser (grid at the back) remains only partially cold or warm, this is a sure sign of a lack of freon circulation.
To more accurately determine the type of plug, technicians use the heating method. If you heat the entry point of the capillary tube into the evaporator or the filter-drier itself, and the pressure in the system begins to drop and the compressor starts working easier, it means the plug is ice. When heated, the ice melts and circulation is temporarily restored. If heating does not have an effect, most likely an oil or mechanical blockage has formed oil or mechanical blockage.
Another method is to check the pressure at the outlet of the compressor. If the system is completely clogged, the pressure gauge will show excess pressure, significantly higher than normal, since the gas has nowhere to go. It is also important to pay attention to the condition of the oil: if it is blackened and has a sour smell, the system has been overheated, and simple purging may not help.
- ❄️ Ice plug - temporary disappearance of the blockage when the narrowing area is heated.
- 🛢️ Oil blockage - viscous consistency oil, lack of response to heating, often accompanied by blackening of the oil.
- 🔧 Mechanical blockage - the presence of solid particles, often occurs after soldering without nitrogen purging.
Accurate diagnostics allows you to choose the optimal repair method. An attempt to blow out an ice plug with nitrogen without preliminary evacuation can lead to only a short-term result, since the moisture will remain in the system and freeze again.
Necessary tools and equipment
High-quality repair of a refrigerator is impossible without specialized equipment. The basic tool is vacuum pumpwhich is necessary to remove moisture and air from the circuit. The pump power must correspond to the volume of the system in order to provide the deep vacuum necessary to evaporate water at low temperatures.
To purge the system and create pressure, you will need a cylinder with dry nitrogen. Nitrogen is inert and contains no moisture, making it ideal for cleaning and leak testing. You will also need a reducer to regulate the gas supply pressure so as not to break the thin evaporator tubes.
You cannot do without a gas burner with solder. For soldering copper tubes, hard solder containing silver is most often used, which provides a strong and tight connection. Soft tin solder is used less frequently in modern refrigerators due to high temperatures and vibrations.
In addition, the master will need pipe cutters, expanders, clamping tools and, of course, a new filter drier. Using an old filter after opening the system is strictly prohibited, since its sorbent is already saturated with moisture and will not be able to perform its function.
Methods for removing ice blockage
Ice blockage is the most common and, fortunately, often removable type of blockage. The essence of the method is to remove moisture from the system by deep vacuum. The process begins by disconnecting the refrigerator from the network and disconnecting the capillary tube from the filter-drier.
After installing the new filter-drier, a vacuum pump is connected to the system. It is important to create a vacuum of at least 200-300 microns. At such low pressure, water in the system in the form of ice or steam begins to boil and evaporate even at room temperature. This process can take from 30 minutes to several hours depending on the amount of moisture.
Sometimes the “defrost and vacuum” method is used. The capillary tube at the site of the blockage is carefully heated with a hair dryer or torch to melt the ice, and the vacuum pump is immediately turned on to draw out the resulting steam. The heating and pumping cycles are repeated until the system is clean.
☑️ Checklist for moisture removal
If after vacuuming and refilling with freon the problem returns after some time, this indicates that moisture is hidden in hard-to-reach places or the oil contains an emulsion. In such cases, a more complex procedure for flushing the circuit is required.
Flushing the system and removing oil blockage
Removing oil blockage or oil polymerization is a much more complex and time-consuming task. Simply purging with nitrogen will not help here, since viscous deposits stick tightly to the walls of the tubes. The only effective method is flushing the system with a special solvent or liquid freon under pressure.
For flushing, seal off the condenser and evaporator, if possible, or flush the entire circuit by connecting the compressor through a special container with flushing liquid. The liquid is forced through the system, dissolving oil deposits, and is then thoroughly removed. This process requires a large amount of flushing agent and time.
⚠️ Warning: The use of aggressive chemical solvents may damage the compressor winding insulation or rubber seals. Use only specialized fluids recommended by the equipment manufacturer.
In cases where flushing does not produce results or the system is too contaminated with oil breakdown products, the only option is a complete replacement of the capillary tube and, possibly, other elements of the circuit. The new tube is selected strictly according to the internal diameter and length, since these parameters determine the operating pressure and cooling capacity.
After washing, a long vacuum must be carried out to remove residual solvent. The remaining liquid can react with new oil or freon, forming an acid that will destroy the compressor from the inside.
Replacing the capillary tube: step-by-step instructions
If cleaning is not possible, the capillary tube is replaced. This is a critical stage that requires precision. First you need to dismantle the old tube, carefully unsoldering it from the filter and evaporator. It is important not to damage the thin evaporator tubes, which can be soldered into a metal plate.
The new tube must have identical characteristics: internal diameter, length and number of turns. Even a slight deviation in length can lead to improper operation of the refrigerator: if the tube is shorter, the condensation pressure will drop and the refrigerator will freeze poorly; if longer, the load on the compressor will increase.
How to solder a new tube correctly?
When soldering a capillary tube into a filter drier, it must be inserted to a depth of 15-20 mm. If you insert it too deeply, you can hit the filter mesh and block the flow of freon. If it is too shallow, the pressure may rip out the tube. The soldering area should be smooth, without solder sagging inside.
The soldering process requires care. Copper gives off heat quickly, so the joint must be heated evenly. The solder should flow into the gap under the action of capillary forces, and not just stick on top. After soldering all connections, the system is sealed tightly for testing with nitrogen.
The tightness test is carried out with a nitrogen pressure of 10-15 atmospheres. The pressure gauge is left for several hours (ideally for a day). If the arrow does not move, it means the soldering is of high quality. After this, the nitrogen is released, a new filter drier is installed and vacuum is carried out.
Comparison of repair methods and possible risks
The choice of repair method depends on the type of blockage and the condition of the equipment. Below is a table that helps compare the main approaches to solving the problem.
| Method | Efficiency | Complexity | Risks |
|---|---|---|---|
| Vacuuming | High (for moisture) | Medium | Residual moisture |
| Nitrogen purge | Low | Low | Tube rupture |
| Circuit flushing | High | High | Insulation damage |
| Tube replacement | Maximum | High | Error in sizing |
The greatest risk during self-repair is damage to the aluminum evaporator tubes. They are very soft and easily burst if handled carelessly. In addition, incorrect refilling with freon after repair can lead to compressor failure.
It is also worth considering that modern refrigerators often use foamed evaporators, access to which is limited. In such cases, replacing the capillary tube may require partial opening of the thermal insulation, which complicates repairs.
Prevention of re-clogging
To avoid re-formation blockages, it is necessary to strictly follow the repair technology. Any opening of the circuit must be accompanied by the immediate installation of a new filter-drier and subsequent evacuation. The time during which the system is open to the atmosphere should be minimal.
It is important to monitor the operating temperature of the compressor. Overheating leads to oil decomposition and carbon deposits. Ensure good ventilation of the rear wall of the refrigerator and regularly clean the condenser from dust.
⚠️ Attention: Do not leave the refrigerator turned on with the tubes open, even for a short time. Moisture from the air is instantly absorbed by the oil and distributed throughout the entire system.
Regular maintenance and timely replacement of door seals also help maintain normal operation, reducing the load on the compressor. Remember that high-quality repair is not only the elimination of a current breakdown, but also a guarantee of a long service life of the unit in the future.
Is it possible to clean the capillary tube with a syringe?
Using a syringe with a solvent is only possible for local cleaning the removed tube, but not for the system as a whole. The syringe pressure is not enough to fully flush the circuit, and introducing liquid in this way does not guarantee the removal of all contaminants.
How much does it cost to replace a capillary tube?
The cost consists of the price of materials (tube, filter, freon, solder) and the work of the technician. On average, repairs cost 30-50% of the cost of a new refrigerator, which makes it worthwhile for mid- and high-class models.
Why does the refrigerator freeze worse after repair?
This may be due to incorrect selection of the length or diameter of the new capillary tube, as well as insufficient or excessive charging of freon. The pressure in the system needs to be adjusted again.
Is nitrogen used during repairs dangerous?
Nitrogen itself is inert and non-toxic, but it displaces oxygen. Work with cylinders should be carried out in a well-ventilated area to avoid suffocation in the event of a large gas leak in a confined space.