If you are faced with the fact that your refrigerator stops freezing, and the compressor works without stopping, there is a high probability of problems with the refrigerant circulation system. Often in such situations, masters mention the mysterious “capillary”. This term may confuse the inexperienced user, but in fact we are talking about a critical design element.
The capillary tube, or simply capillary, is a thin copper pipe that connects the condenser and the evaporator. It is through it that the liquid passes under high pressure, after which it expands sharply and cools. Understanding the operating principle of this unit will help you quickly diagnose a breakdown and avoid unnecessary diagnostic costs. freon, after which it expands sharply and cools. Understanding the operating principle of this unit will help you quickly diagnose a breakdown and avoid unnecessary diagnostic costs.
In this article we will look in detail at why a blockage occurs, how to distinguish it from a gas leak and whether it is possible to make repairs yourself. A clogged capillary tube is a mechanical blockage that cannot be eliminated by simply rebooting the equipment. You will have to prepare for more complex procedures related to vacuuming and filling the system.
The operating principle and purpose of the capillary tube
The main function of the capillary is in creating a pressure difference between two circuits of the refrigeration system. On one side of it there is a high pressure zone (compressor discharge and condenser), and on the other there is a low pressure zone (evaporator). Passing through a narrow hole with a diameter of less than a millimeter, it is refrigerant throttled.
During the throttling process, the liquid turns into steam, actively absorbing heat from the refrigerator chambers. The length of the tube and the diameter of its internal section are calculated by engineers with mathematical accuracy for each specific model. Replacing the original part with an analogue with other parameters may lead to incorrect operation of the entire system.
- 🧊 Provides a sharp drop in the refrigerant temperature before entering the evaporator.
- ⚖️ Balances the pressure in the high and low pressure circuits.
- 🔄 Regulates the volume of incoming into the liquid freon evaporator.
It is worth noting that in modern models Indesit or Atlant the capillary is often soldered directly into the defrost circuit or glued to the back side of the evaporator. This makes replacing it a technically difficult task, requiring special tools and soldering skills.
Main causes of system blockage
Why does such a thin tube become clogged? Most often, the culprit is moisture that entered the circuit during poor-quality repairs or due to a leak. Water freezes in the narrowest place, forming an ice plug that completely blocks the flow of gas.
The second common reason is the oxidation of copper. If the wrong solder was used during installation or nitrogen purge was not used, oxides may form inside. Over time, they accumulate and turn into particulate matter that blocks the passage. Also, decomposition products of compressor oil.
⚠️ may enter the system. Attention: An attempt to break through the blockage by increasing the compressor pressure can lead to rupture of the tube in another place or damage to the unit itself.
Sometimes the blockage is temporary. The ice cap may thaw if the refrigerator is left turned off for a long time (more than 24 hours). However, after switching on, the problem will most likely return in a few hours or days.
Symptoms of capillary malfunction
The problem can be diagnosed by indirect signs, without opening the case. The first alarm bell is the lack of cold when the engine is running. You hear the hum of the compressor, but it is warm inside the chambers. In this case, the condenser grid at the back may be only partially cold or warm.
Another sign is cyclical operation. The unit may freeze normally for several hours and then stop. This is typical for the so-called “floating” blockage, when an ice plug either forms or melts. In such cases, diagnosis becomes more complicated.
Compare the symptoms with other breakdowns in the table below:
| Symptom | Capillary blockage | Freon leakage | Malfunction thermostat |
|---|---|---|---|
| Compressor operation | Continuous or with pauses | Continuous or off | Does not turn on or off |
| Condenser temperature | Hot only at the exit | Cold everywhere | Hot along the entire length |
| Sound of operation | There may be gurgling | Silence or hissing | Normal hum |
| Frost on the evaporator | Absent or partially | Absent | A layer of snow or no frost |
Diagnostics and search for the blockage
To accurately determine the location of the blockage, technicians use the palpation method. When the compressor is running, the tube in front of the capillary will be hot, and immediately after it will be cold or room temperature. A sharp temperature change indicates where the freon has stopped.
If you cannot visually and tactilely find the place, deeper intervention is required. It is necessary to disconnect the capillary tube from the filter drier and flush it with nitrogen. The gas flow resistance of a working tube should be uniform. If nitrogen does not pass, then clogging confirmed.
In some cases, especially in older models Stinol or Biryusa, the blockage may be localized at the point where the tube enters the foamed contour. This is the worst scenario, as it requires either foaming the entire cabinet or installing a new evaporator (“crying” or “no frost”).
Technology for cleaning and replacing parts
Repairing a capillary system is not just replacing a tube. This is a complex of works that requires adherence to technology. First, the old part is dismantled. If it is glued to the evaporator, it is carefully separated, being careful not to damage the aluminum channels.
Then the vacuum process follows. Using a vacuum pump, air and remaining moisture are removed from the system. This is a critical step, without which a new blockage is guaranteed. The evacuation time depends on the power of the pump and usually ranges from 30 minutes to an hour.
- 🔧 Soldering the old capillary and filter drier.
- 🧹 Blowing the circuit with nitrogen under pressure to remove chips.
- 🔥 Soldering a new tube using silver solder.
- 💨 Evacuate the system for 40-60 minutes.
- ⛽ Filling with the exact amount of refrigerant (by weight).
After installing the new part, it is necessary to check the tightness of the connections. To do this, pressurized nitrogen and a soap solution or an electronic leak detector are used. Only after making sure that there are no leaks can you refill.
☑️ Procedure for replacement
Filling refrigerant and testing
The amount of freon required for operation is strictly regulated by the manufacturer. Information about this is indicated on a label located inside the refrigerator compartment or on the back wall. For different types of gas (R134a, R600a) different pressure gauge stations are used.
Refueling is carried out with the compressor running, monitoring the pressure on the low pressure gauge and the current consumption of the electric motor. An excess of gas is just as dangerous as a lack of it. In the first case, liquid freon can enter the compressor, causing water hammer.
⚠️ Attention: R600a gas (isobutane), used in many modern models, is explosive. Work with it should be carried out in a well-ventilated area away from open fire.
After refueling, the refrigerator is left to work for several hours. The uniformity of cooling of the evaporator, the temperature in the chambers and the on-off cycle are checked. If all parameters are normal, the tubes are finally sealed.
Is it possible to use a car compressor for purging?
Theoretically, it is possible to create pressure, but car compressors produce moist air and cannot create the necessary vacuum. The use of such equipment is guaranteed to lead to re-clogging in a short time.
Prevention and service life
The capillary tube is an element that does not require scheduled replacement. With proper operation and high-quality initial installation, it lasts as long as itself refrigerator. The basic rule of prevention is to prevent independent intervention in the system without the presence of equipment.
If you notice that the refrigerator has begun to work worse, do not try to “treat” it with traditional methods. A timely call to a technician will allow you to eliminate the problem at an early stage, perhaps by only replacing the filter-drier if the blockage has not yet become critical.
Regular defrosting (for drip systems) and keeping the heat exchanger clean also contribute to stable pressure in the system. Dust on the condenser causes the compressor to wear out, which can indirectly affect oil circulation and the condition of the tubes.
Frequently asked questions (FAQ)
How much does it cost to replace a capillary tube?
The cost consists of the price of materials (copper, solder, gas, filter) and the complexity of the work. On average, repairs cost 30-50% of the cost of a new refrigerator, as they require a highly qualified technician.
Is it possible to restore an old refrigerator with a blockage?
Yes, if the housing and compressor are in good condition. However, for models older than 15-20 years, repairs may not be economically feasible due to wear and tear of other components.
Why does the refrigerator freeze poorly after replacing the tube?
Perhaps there is air or moisture left in the system, or the amount of refrigerant charged is incorrect. Also, the reason may be a poor-quality filter-drier.
How long can a refrigerator operate with a clogged capillary?
Long-term operation in this mode is dangerous for the compressor, which overheats while trying to pump gas through the plug. This can lead to engine wedge and costly replacement of the unit.