Understanding where is the capillary tube in the refrigeratoris key to diagnosing most cooling problems. This thin copper element serves as a choke in the entire system, creating the necessary resistance to the refrigerant. It is thanks to it that freon passes from a liquid state to a gaseous state, actively absorbing heat inside the chambers.
Visually detecting this component without dismantling the back panel is almost impossible, since it is hidden in thermal insulation or sandwiched between the walls of the case. However, knowing its exact location and operating principle will allow you to independently determine the reason for the lack of cold or the formation of an ice coat. Let's look at the anatomy of the cooling system in more detail.
If you notice that your Indesit or Atlant has stopped freezing, but the compressor is running continuously, there is a high probability of a blockage in this particular unit. Unlike temperature sensors, which can be checked with a multimeter, diagnosing a capillary requires analyzing indirect signs and pressure in the system. It is important to understand that self-repair of the freon circuit requires special tools.
Design features and principle of operation
The capillary tube is a long copper pipeline of very small diameter, usually from 0.6 to 2 mm. Its length can vary from 2 to 6 meters depending on the power of the compressor and the type of refrigerant. The main task of this element is to create a pressure difference between the condenser (high pressure) and the evaporator (low pressure).
Passing through this narrow channel, liquid freon is throttled, expands sharply and boils at low temperatures. This process ensures the extraction of heat from the products. If the tube is too short or wide, the freon will not have time to completely evaporate, and liquid drops will fall into the compressor, which will lead to water hammer. Water hammer can instantly disable an expensive motor.
In modern models such as LG No Frost or Bosch, the capillary is often embedded directly into the wall of the housing or foamed together with the evaporator. This makes replacing it an extremely labor-intensive procedure that requires opening the thermal insulation. In older models with an open evaporator, this element is often visible visually after removing the back cover.
⚠️ Attention: The length and diameter of the capillary tube are calculated by engineers with millimeter accuracy. Replacing with a similar one “by eye” without taking into account the length and diameter will lead to incorrect operation of the refrigerator or failure of the compressor.
The manufacturing material is always copper, since it has high ductility and thermal conductivity. However, during installation it is important to avoid kinks that could completely block the refrigerant flow. Even microscopic deformation can disrupt the operation of the entire system.
The exact location in different types of refrigerators
The answer to the question of where exactly to look for a capillary depends on the design of your unit. In classic two-chamber models with a drip defrosting system, the tube often runs along the back wall inside the cabinet or is glued to it from the outside. It can be tinned or coated with a special varnish to protect against corrosion.
In systems No Frost the situation is more complicated. Here the capillary tube is usually located inside a foamed loop or hidden under a plastic panel in the freezer. It is in close contact with the evaporator, which is located behind the rear wall. You can get to it only after completely disassembling the freezer compartment.
- 📍 Classic models: The tube is visible on the back wall inside the chamber, often running like a snake or parallel to the defrost circuit.
- 📍 No Frost systems: Hidden behind a plastic panel in the freezer, integrated into the block evaporator.
- 📍 Built-in refrigerators: They often have a remote condenser, and the capillary can be part of a foamed circuit around the perimeter of the door or body.
Sometimes, especially in budget models Biryusa or Stinol, the capillary can be brought out in the form of a coil on the rear wall of the housing (capacitor), but the throttle section itself is still hidden. You can find its beginning at the filter drier, which is a small copper cylinder next to the compressor.
If you are planning a repair, you need to accurately determine the type of system. Models with one compressor and two chambers often use a single capillary with a solenoid valve that switches flows. In two-compressor systems, each circuit has its own independent capillary.
How to recognize a malfunction of the capillary system
Diagnostics of problems with the capillary often comes down to analyzing the operation of the compressor and temperature conditions. The most common problem is clogging. An ice blockage may form in the system due to moisture or a paraffin/oil blockage due to poor-quality oil or aging components.
When a blockage occurs, the compressor starts working non-stop, trying to gain temperature, but there is no cold. In this case, the condenser (grid at the back) may be barely warm or cold, since freon does not circulate. Another sign is swelling of the side walls of the refrigerator if the tube is laid inside them and a blockage has occurred.
The second variant of the malfunction is mechanical damage or leakage at the soldering point. If you hear a hissing sound or see oily spots where the tube exits the foamed area, the seal has failed. In this case freon gradually evaporates and the refrigerator stops cooling.
| Symptom | Probable cause in the capillary | Condition of the condenser |
|---|---|---|
| The compressor is humming, there is no cold | Complete blockage (paraffin, moisture) | Cold or barely warm |
| The refrigerator freezes slightly | Partial blockage or leakage | Only partially heated |
| Bloating of the housing wall | Clogging in the foam circuit | Hot at the point of swelling |
| Oil stains at the back | Microcrack in the tube | Normal heating (as long as there is gas) |
It is also worth paying attention to the operation of the switching valve, if there is one. If the valve is stuck, freon will not flow into one of the chambers. You can check this by touching the tubes at the entrance to the chambers: one will be hot, the other cold, although both should warm up (in cooling mode).
Instructions for replacement and repair (for pros)
Replacing a capillary tube is a complex process that requires a vacuum pump, a pressure gauge station and skills in soldering copper pipes. Before starting work, it is necessary to completely release the system from residual refrigerant pressure. This should be done in a well-ventilated area.
First, the old capillary is dismantled. If it is foamed, it is often not pulled out completely, but new ends are cut and soldered, laying a new tube on top or next to it, if the design allows. It is important to maintain the length and diameter of the original. The new capillary is soldered at one end to the filter-drier, and at the other to the evaporator.
☑️ Checklist before soldering
After installing the new element, the system must be vacuumized for 15-20 minutes. This is a critical step for removing moisture. Only after creating a deep vacuum is freon charged strictly according to the weight indicated on the compressor nameplate.
⚠️ Attention: Using an open flame when soldering next to thermal insulation (polyurethane foam) is dangerous. Thermal insulation burns and releases toxic substances. Be sure to cut out the foam around the soldering area or use a wet cloth for protection.
For soldering, use hard solder containing silver (for example 30% Ag), as it provides better sealing and strength of the connection during compressor vibrations. Soft tin solder may not withstand pressure and temperature expansion.
Common mistakes during self-repair
Many amateur craftsmen make a fatal mistake when trying to clear the blockage by blowing with their mouth or a compressor. This is strictly prohibited! Introducing moisture from the lungs or oil from a car compressor will completely kill the system, turning a simple blockage into a complex chemical reaction inside the circuit.
Another mistake is ignoring the replacement of the filter drier. When the system depressurizes or operates for a long time, the filter becomes saturated with moisture. If you leave the old filter in place when replacing a capillary, the new tube will clog within a few weeks. The filter drier is a disposable element.
- ❌ Heating the tube: An attempt to warm up the clogged area with a blowtorch often leads to burning through thin copper and an insulation fire.
- ❌ Using wire: Pushing the wire inside the capillary deforms its walls, creating new obstacles for frequency data-i="124">They also often forget to check the integrity of the compressor windings after a long period of inactivity or operation without cooling. If the motor overheats, its insulation could be damaged, and after repair it will burn out in the first minutes of operation.
- ❌ Refilling by eye: Adding freon without scales and pressure gauges will lead to either underfilling (poor cooling) or overfilling (liquid freon in the compressor).
They also often forget to check the integrity of the compressor windings after a long period of inactivity or operation without cooling. If the motor overheats, its insulation could be damaged, and after repair it will burn out in the first minutes of operation.
Is it possible to restore the old capillary?
Theoretically, if the blockage is caused by paraffin, you can try to warm up the system and blow it with nitrogen under high pressure by replacing the filter. However, at home (the probability of success) is extremely low. It is easier and more reliable to replace the entire tube.
Prevention and care of the cooling system
In order for the capillary tube to serve for a long time, it is important to monitor the temperature conditions of the refrigerator. Do not load hot food into the chamber as this will place excessive stress on the system and may cause sediment to form in the oil. Regular defrosting (for drip systems) also prolongs the life of the unit.
Keep the condenser at the back of the refrigerator clean. Dust and animal hair adhering to the grille impair heat transfer. The compressor is forced to work longer, the pressure in the system increases, which increases the risk of a breakthrough in the weakest places, which are the thin sections of the capillary.
If you notice that the refrigerator has started to work louder or the switching cycles have become more frequent, do not ignore it. Early diagnosis allows the problem to be corrected before complex component replacement is required. Check the door seals - if they allow heat to pass through, the system is wearing out.
In conclusion, it is worth noting that although knowledge of the refrigerator's structure is useful, repairing the freon circuit is best left to professionals with a license to work with refrigerants. Incorrect soldering or filling can make repairs economically unfeasible.
Is it possible to replace the capillary tube with a longer or shorter one?
No, this is unacceptable. The length and diameter of the tube are calculated by engineers for the specific compressor performance and evaporator volume. Changing the parameters will upset the pressure balance: the freon will either not have time to evaporate (risk of water hammer) or will evaporate too early (loss of refrigeration capacity).
Why does the capillary tube sometimes become covered with frost?
Frost on the capillary (usually at the beginning, at the entrance to the evaporator) is a normal phenomenon, since there is a sharp expansion of gas there and cooling. However, if frost “creeps” back through the tube to the compressor, this is a sign of a lack of freon or problems with thermoregulation.
What is the diameter of a standard capillary tube?
In domestic refrigerators, tubes with an internal diameter of 0.66 mm to 1.0 mm are most often used. The exact size depends on the type of refrigerant (R134a, R600a) and compressor power. For R600a (isobutane), longer and thinner tubes are often used due to the properties of the gas.
How much does it cost to replace a capillary tube?
The cost consists of the price of materials (copper, filter, freon) and the complexity of the work. In service centers, the price can vary from 3,000 to 8,000 rubles and higher, since the work requires high qualifications and time. In foamed systems, the price will be maximum due to labor intensity.