Faced with a situation where the refrigerator compressor works almost without interruption, and there is above-zero temperature inside the chambers, many equipment owners begin to panic. Most often, this scenario indicates that Freon cannot circulate through the system due to blockage. Capillary tubebeing the narrowest section of the circuit, it takes the brunt when impurities or moisture appear in the refrigerant. An attempt to independently eliminate this defect requires not only theoretical knowledge, but also the presence of specific equipment, without which a high-quality pumping system is impossible.
There are two main types of blockages that DIYers and enthusiasts have to deal with: oil-paraffin blockage and ice blockage. In the first case, the culprit is thickened oil or decomposition products, in the second - moisture that turned into ice when leaving the high pressure zone. It is important to understand that simply cleaning the tube will not solve the problem if the root cause is not eliminated, for example, it is not replaced drying filter. Ignoring this rule will lead to repeated failure of the unit in a short time.
Before taking active steps, you need to soberly assess your strengths and the availability of tools. Working with a sealed circuit involves violating its integrity, which requires subsequent evacuation and refilling. If you do not have a pressure gauge station or a cylinder, further manipulations may be useless. However, if you are determined to understand the device and have a minimum set of plumbing tools, this article will become a detailed guide for you. data-i="60">The first step in any repair is the correct diagnosis. The symptoms of a clogged capillary tube are quite specific and different from problems with the thermostat or a gas leak. The compressor turns on and runs continuously, trying to build up the temperature, but the evaporator either remains warm or only cools in the initial part. To the touch nitrogen, further manipulations may be useless. However, if you are determined to understand the device refrigeration circuit and have a minimum set of locksmith tools, this article will become a detailed guide for you.
Diagnosis and signs of system blockage
The first step in any repair is a correct diagnosis. The symptoms of a clogged capillary tube are quite specific and different from problems with the thermostat or a gas leak. The compressor turns on and runs continuously, trying to build up the temperature, but the evaporator either remains warm or only cools in the initial part. To the touch condenser (the grille at the back) may be slightly warm or cold, which indicates a lack of refrigerant circulation.
If you listen to the operating unit, you will notice the absence of the characteristic noise of gurgling or liquid flow, which is usually heard during normal operation. In some cases, especially with partial blockage, gurgling may occur, but it will be dull and intermittent. Experienced technicians also pay attention to the temperature of the compressor housing: if there is severe blockage, it can overheat due to operation in vacuum suction mode.
To accurately determine the location and type of blockage, the method of local heating or cooling is often used. Heating a section of the tube before entering the evaporator can temporarily remove the ice plug, which will manifest itself in the appearance of a characteristic sound and cooling of the evaporator. However, oil blockage cannot be eliminated in this way. It is important to distinguish between these conditions, since the methods of dealing with them are fundamentally different.
⚠️ Attention: Prolonged operation of the compressor with a clogged system can lead to overheating and thermal breakdown of the windings. If signs of blockage are detected, operation of the refrigerator should be stopped immediately.
Accurate diagnosis is impossible without a visual inspection and pressure check. If, when connecting the pressure gauge on the suction line, the arrow goes into a deep vacuum and shows high pressure on the discharge line, the diagnosis is confirmed. This is a classic picture when freon there is, but it is locked in the condenser and does not enter the evaporator.
Necessary tools and materials
High-quality repair of the refrigeration system impossible without a specialized tool. Trying to make do with improvised means will, at best, lead to a loss of time, and at worst, to damage to expensive components. The basic set includes copper working tools and measuring equipment. It is strictly not recommended to start work without a filling station, since moisture and air in the system will destroy the compressor. vacuum pump and a gas station, it is strictly not recommended to start work, since moisture and air in the system will destroy the compressor.
Particular attention should be paid to the source of pressure for purging. The ideal option is a dry nitrogen cylinder, which allows you to create high pressure and does not contain moisture. Using compressed air from a compressor is only permissible if you have a high-quality moisture-oil separator, otherwise you risk introducing additional water into the system, which will worsen the situation.
To work with copper tubes you will need a torch (gas or oxy-acetylene), solder and flux. We also use a pipe cutter and a roller if you need to replace sections of the main line. Do not forget about personal protective equipment, since the work involves high temperatures and chemically active substances.
☑️ Preparation for refrigerator repair
Methods for cleaning the capillary tube
There are several proven ways to remove blockages, the effectiveness of which depends on the type of blockage. The most common and accessible method is high pressure nitrogen purging. This method allows you to push oil clots or dirt particles out of a narrow channel. The pressure during purging must be controlled so as not to damage the thin walls of the capillary tube. If purging does not produce results, the backwash method is used. In this case, pressure is supplied in the opposite direction - from the evaporator side. This will often help break through a blockage that has formed at the entrance to the tube. However, it is worth remembering that it is not always possible to completely clean a long and winding channel in this way. capillary tube.
If purging does not produce results, the backwash method is used. In this case, pressure is supplied in the opposite direction - from the evaporator side. This will often help break through a blockage that has formed at the entrance to the tube. However, it is worth remembering that it is not always possible to completely clean a long and winding channel in this way.
In the case of an ice plug caused by moisture entering the system, purging may be ineffective without first drying it. Heating the tube with a hairdryer or torch while simultaneously blowing helps here. The warm gas flow carries away moisture vapor, but this method requires caution so as not to overheat the solder or the copper itself.
The most radical, but also the most reliable method is to replace the capillary tube. If the blockage is caused by internal deposits along the entire length, cleaning will only give a temporary effect. A new tube with a precisely selected diameter and length guarantees the restoration of the calculated throttling and proper operation of the refrigerator.
⚠️ Attention: The use of oxygen to create pressure in the system is strictly prohibited! A mixture of oxygen with oil and refrigerant vapor can lead to an explosion.
Replacing and installing a new filter drier
The filter drier is a critical element that retains moisture and mechanical impurities. Whenever the circuit is opened, especially when removing a blockage, its replacement is mandatory. The old filter is already saturated with moisture and will not be able to protect the system from the re-formation of ice plugs. Neglecting this rule is the most common mistake leading to a quick relapse.
The replacement process begins with the careful removal of the old element. The copper tubes leading to the filter are cut, and the old housing is removed. It is important not to overheat the new filter when soldering, since there is zeolite inside it, which loses its properties at temperatures above 100-120°C. Soldering should be done quickly, using a damp rag to cool the filter housing.
When choosing a new element, you need to pay attention to its throughput and the type of refrigerant for which it is intended. Modern refrigerators operating on R600a or R134arequire specific filter models. Installing a universal filter “by eye” can lead to an imbalance in the system.
| Type of blockage | Probable cause | Remedy method | Need to replace the filter |
|---|---|---|---|
| Ice plug | Moisture ingress | Blowing with heating | Required |
| Oil blockage | Compressor wear | Nitrogen purging | Required |
| Mechanical debris | Destruction parts | Flush the system | Required |
| Paraffin plug | Poor quality oil | Replace the tube | Required |
Why can’t you leave the old filter?
The old filter-drier has a limited resource. After opening the circuit, it instantly absorbs moisture from the air. If it is not replaced, after a few days or weeks moisture will appear in the capillary tube and the refrigerator will stop freezing again. Saving on this element is pointless.
The process of evacuation and refrigerant charging
After successful cleaning of the system and replacement of the filter, the stage of preparation for launch begins. The main enemy of the refrigeration circuit is moisture and air. Even a microscopic amount of water can freeze in the capillary tube and ruin all your efforts. Therefore, the procedure vacuuming is an integral part of the repair.
A vacuum pump is connected to the system and a vacuum is created. The process should last at least 30-40 minutes, and for large systems - up to an hour. The vacuum gauge should show a stable value close to the limit value for a given pump. If the pressure gauge needle creeps up after the pump is turned off, it means that there is a leak in the system that needs to be found and eliminated.
Refrigerant charging is carried out strictly according to the weight indicated on the nameplate of the refrigerator. The use of a scale cylinder or electronic scale is mandatory. Filling "by eye" or by pressure (especially for R600a) is unacceptable, as it can lead to improper operation and overload of the compressor. After refilling, it is necessary to check the tightness of all soldered joints with a soapy solution.
Typical mistakes during self-repair
Many amateur craftsmen make mistakes that reduce the result of their work to zero. One of the most common is an attempt to blow out the system with your mouth or a regular car compressor. In both cases, a huge amount of moisture enters the system, which is guaranteed to create a new ice plug in a short time.
Another mistake is to ignore flushing the condenser in case of severe oil blockage. If “cotton” oil (emulsion) occurs in the system, it settles on the walls of the heat exchanger. Without flushing with a solvent and subsequent purging, the new compressor or filter will quickly fail.
Often the length of the capillary tube is incorrectly selected when replacing it. Reducing the length will lead to an increase in pressure in the evaporator and overloading the compressor, and increasing it will lead to underload and poor cooling. It is necessary to strictly observe the parameters specified by the manufacturer, or select an analogue according to the correspondence tables.
⚠️ Attention: Technical characteristics of refrigerators may vary depending on the model and year of manufacture. Always check the official documentation or markings on the nameplate of a specific device before starting work.
Don't forget about safety. Working with high pressure and flammable gases requires concentration. Improper soldering can lead to gas leaks and fire, and failure to ground the tool can result in electric shock. If you doubt your abilities at any stage, it is better to turn to professionals.
Frequently asked questions (FAQ)
Is it possible to clean the capillary tube without nitrogen?
Theoretically, you can try using compressed air with a high-quality filter-moisture separator, but this is risky. Residual moisture in the air can become trapped in the system. Nitrogen is preferred because it is inert and dry. Using a rotary or conventional compressor without drying is guaranteed to lead to re-clogging.
How much does it cost to replace a capillary tube during service?
The cost consists of the price of materials (pipe, filter, refrigerant) and the work of the technician. On average, this can range from 30% to 60% of the cost of a new compressor. The exact price can only be found out after diagnostics, since additional flushing of the system is often required.
Why does the refrigerator freeze after cleaning, but then stops again?
Most likely, there is moisture left in the system that was not removed during vacuuming, or the filter drier was not replaced. Moisture circulates through the system and periodically freezes in the narrowest place - the capillary tube, blocking the freon flow.
Is it possible to use flushing liquid for cleaning?
Yes, special liquids (for example, based on alcohols or ethers) are used to flush the system from oil contaminants. However, after flushing, the system must be thoroughly purged with nitrogen and vacuumed to remove any remaining liquid, otherwise it will react with the compressor oil.
How can you tell that it is the capillary that is clogged and not the filter?
Often both elements become clogged or the filter is the cause of the capillary being clogged. When depressurizing, the filter is usually cut out, and if gas under pressure does not flow from the capillary, it means that it is also clogged. In modern practice, the filter and capillary are often changed together to guarantee the result.