Capillary tube in the refrigerator: how it works, why it clogs and what to do

Have you ever wondered why your refrigerator suddenly stopped freezing even though the compressor is running non-stop? Or why did frost appear on the back wall, although the system No Frost should prevent this? In 80% of such cases, a small but critical detail is to blame - capillary tube. This is a thin copper channel that regulates the supply of refrigerant to the evaporator, just as an artery supplies blood to the heart.

Without a capillary tube, the refrigerator simply will not be able to maintain the desired temperature. It works in tandem with filter-dryer and thermostatic valve (in modern models), forming the so-called throttle node. But despite its simple design, this part often becomes a source of headaches for owners. Why? Because its diameter is comparable to the thickness of a human hair - from 0.5 to 2 mm, and the slightest clogging leads to failure of the entire system.

In this article we will look at:

• 🔍 How the capillary tube works and why it is so important for the refrigerator
• ⚠️ Signs of clogging or damage - from increased noise to complete absence cold
• 🛠️ Is it possible to clean the pipe yourself (spoiler: yes, but not always)
• 💰 Cost of repairs at a service center vs. purchasing a new part

If your refrigerator Atlant, Indesit, Samsung or LG starts to freeze poorly, do not rush to call a technician. Perhaps the problem lies right here, and you can fix it without expensive repairs.

1. What is a capillary tube and where is it located in the refrigerator

A capillary tube is throttling devicewhich reduces the pressure of the refrigerant (freon) before it enters the evaporator. Think of it like the narrow neck of a bottle: liquid freon under high pressure passes through this “gap”, expands and cools, turning into gas. It is this process that creates cold inside the chamber.

In most refrigerators, the tube is located:

• 📍 On the back wall, next to compressor i condenser (that ribbed grille that heated)
• 📍 Inside the polyurethane foam insulation of the case (in modern models, for example, Bosch KGE39XW2AR or Liebherr CNef 4815)
• 📍 Under the plastic panel at the bottom of the refrigerator (often in models Samsung RB30J3200EF)

The length of the capillary tube varies from 1.5 to 6 meters, and the diameter - from 0.5 to 2 mm (depending on the model and type of refrigerant). data-i="92">the tube is thinner than in systems with isobutane (R600a) the tube is thinner than in systems with freon R134abecause the first has a lower viscosity.

Interesting fact: in Soviet refrigerators (ZIL-63, Minsk-15M) the capillary tube was part of a single copper circuit and was often soldered by hand. In modern models, it is usually soldered to the filter-drier and condenser at the factory, which complicates its replacement.

Why is the tube called “capillary”?

The term comes from the Latin “capillaris” (hair), because its internal diameter is comparable to the thickness of a hair. This allows you to accurately dose the flow. refrigerant.

2. Operating principle: how a capillary tube creates cold

To understand why a clogged tube leads to breakdown, let's figure out how it works in the cooling cycle:

1. Compressor compresses gaseous freon, increasing its pressure and temperature (to +70...+90°C).
2. Hot freon enters condenser (rear grill), where it is cooled and condensed into liquid.
3. Liquid freon under high pressure enters in filter-drier, where it is cleaned of moisture and mechanical impurities.
4. Capillary tube sharply reduces the freon pressure, and it begins to boil (evaporate) already in evaporator (freezer).
5. When evaporating, freon takes heat from the chamber, cooling it. Then the gas returns to the compressor, and the cycle repeats.

A critical feature of the capillary tube: it has no moving parts, but its throughput directly depends on the cleanliness and internal diameter. If the tube becomes clogged (for example, with oil decomposition products or moisture), the freon pressure in front of the evaporator does not fall strongly enough. As a result:

• ❄️ The evaporator does not cool to the desired temperature (or is covered with ice unevenly).
• 🔥 The compressor works non-stop, trying to “push” freon through the blockage.
• ⚡ Electricity consumption increases on 20-40%.

In refrigerators with a system No Frost the capillary tube is often connected to thermal expansion valve (TEV), which dispenses freon more accurately. But even in such models (for example, Samsung RB37J5230SS) clogging of the tube leads to the same problems.

3. Signs of a malfunction of the capillary tube

How to understand that the problem is in the capillary tube, and not in the compressor or freon leak? data-i="132">Symptom

One of the most obvious signs is the compressor works constantly, but there is no cold. This happens because the freon cannot pass through the blockage, and the pressure in the system does not drop. As a result, the compressor “thinks” that it needs to pressurize further, although this is useless.

Another alarm signal is the condenser stays cold. Normally it should heat up (sometimes up to +50...+60°C), because hot freon passes through it, the freon does not circulate. data-i="156">condenser remains cold

⚠️ Attention: If the refrigerator stops freezing, but the compressor does not turn on at all, the problem is more likely in start relay or thermostatrather than in the capillary tube.

4. Why the capillary tube gets clogged: main reasons

Clogging of the tube does not occur instantly, but gradually. Here are the main reasons:

• 🛢️ Oil decomposition —over time, compressor oil oxidizes and forms tarry deposits that stick in narrow places of the tube.
• 💧 Moisture in the system —if freon was not replaced when refilling filter drier, moisture from the air reacts with oil, forming acids and sludge.
• 🔧 Mechanical particles —after inaccurate soldering or repairs, copper filings or solder may enter the system.
• ❄️ Ice formation —if moisture gets into the system, at low temperatures it freezes, blocking the tube (a common problem in freezers Indesit BIAA 13).
• 🧪 Poor quality freon —fake or old refrigerants (for example, R12 instead R134a) may contain impurities that settle on the walls.

The most dangerous situation is when a blockage occurs in beginning of the tube (from the condenser side. In this case, freon). does not enter the evaporator at all, and the refrigerator completely stops freezing. If the blockage is closer to output (from the evaporator side), there will be cold, but weak, and the compressor will work with overload.

In refrigerators with isobutane (R600a) clogs occur less often, because this refrigerant is less aggressive to oil. But if the tube does become clogged, it is more difficult to clean it due to the high volatility of the gas.

⚠️ Attention: If you have recently filled the refrigerator with freon, and after 1-2 months it stopped freezing again, most likely, the technician did not replace the filter drier. This is a gross mistake that leads to re-clogging.

5. How to clean the capillary tube with your own hands

If you are sure that this is the problem. if the tube is clogged, you can try to clean it yourself. You will need:

• 🔧 Gas cylinder with nitrogen (or a compressor with a pressure of up to 15 bar)
• 🔥 Blowtorch or hair dryer (for warming up the tube)
• ✂️ Pipe cutter or hacksaw for metal
• 🧲 Magnet (for searching for metal particles in oil)
• 🛢️ New filter drier (required!)

Step-by-step instructions:

1. Disconnect the refrigerator and defrost it for 12-24 hours. This is necessary so that the freon condenses in the condenser.
2. Find the capillary tube —it comes from filter-drier to the evaporator. Usually this is a thin copper tube soldered to a thicker one (return line).
3. Bite your pipe with a pipe cutter 10-15 cm from the filter-drier. Be careful - there may be residual pressure inside!
4. Connect a nitrogen cylinder through the adapter to the return line (thick tube) and blow out the system for 5-10 minutes. The pressure should be 10-12 bar.
5. Warm the tube with a hairdryer - this will help dissolve the resinous deposits. Heat a section 30-40 cm long to +100...+150°C.
6. Repeat. purge and check if the particles fly out of the tube. If the blockage is cleared, you will hear a uniform whistle of air.
7. Install a new filter drier and solder the tube. Use silver solder (for example, Castolin 157) and flux for copper.
8. Fill the system with freon (you need a manometric manifold and accurate scales for dosage).

If the blockage is not cleared by blowing, you can try push it mechanically:

1. Cut the tube closer to the evaporator.
2. Insert a flexible cable into it (for example, from a bicycle brake) and carefully clean it.
3. Rinse the tube acetone or special solvent for refrigeration systems (for example, RC FLUSH).

⚠️ Attention: Under no circumstances use wire or metal objects with burrs for cleaning - they can damage the inner walls of the tube, which will lead to a new blockage.

Disconnect the refrigerator from the mains|Defrost for at least 12 hours|Prepare a nitrogen cylinder or compressor|Buy a new filter drier|Wear safety glasses and gloves

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6. When is it better to call a technician: complex cases

Not all. You can clear the blockages yourself. Contact the service center if:

• 🔧 The tube is clogged in several places (for example, at both the filter and the evaporator).
• 💥 When purging with nitrogen tube bursts —this means that the metal is outdated and needs a complete replacement.
• 🧊 The blockage is accompanied by freon leak (determined by oil stains on the tubes).
• 🔄 Refrigerator has already been repaired for this reason, and the problem returned (perhaps the filter drier was not replaced).
• ⚡ You are not confident in your skills soldering - an error when sealing the tube will lead to a new leak.

Cost of repairs at the service center:

In some cases, the technician may suggest replace the capillary tube with a thermostatic one. valve (TRV)this is a more modern solution that is less likely to clog and doses freon more accurately. However, such repairs will cost more (8,000–12,000 rubles.) and require reconfiguring the system.

If your refrigerator is older than 10 years (for example, Stinol 103 or Atlant XM-4021), think about the feasibility of repairs. Replacing the capillary tube may cost up to 50% from the price of a new refrigerator.

7. Prevention: how to extend the life of the capillary tube

To avoid clogging of the tube, follow these recommendations:

• 🔄 Defrost the refrigerator at least once a year (even if you have No FrostThis will help remove condensation from the system.
• 🛢️ Change the filter drier every time you refill freon. This rule is often ignored, but it is critical for the longevity of the system.
• 🧴 Use high-quality oil for the compressor (for example, Emkarate RL 32H or Bitzer BSE 32). Cheap analogues oxidize faster.
• 🔧 Do not repair the refrigerator “on the knee” - soldering without vacuuming the system leads to moisture ingress.
• 🌡️ Monitor the room temperature. If the refrigerator is in a hot room (above +30°C), the compressor is overloaded, and the oil deteriorates faster.

In refrigerators with isobutane (R600a) the capillary tube lasts longer, but they are more sensitive to leaks. If you notice oil stains under the refrigerator, immediately check the system for leaks.

One of the signs is initial clogging the refrigerator became longer to increase the temperature after defrosting. If before it cooled in 1-2. hours, and now - in 4-5, this is a signal to action.

8. Frequently asked questions about capillary tubes

Is it possible to replace the capillary tube with a wider one so that it does not clog?

No. The diameter of the tube is strictly designed for the specific refrigerant and compressor power. throttle, and the refrigerator will lose performance. In some cases, the technician can install thermostatic valve (TEV) instead of a capillary tube, but this requires reconfiguring the system.

How can you tell that the tube is clogged and there is no freon leak?

If there is a leak, the compressor will be turn on and off quickly (since the pressure in the system drops). If the tube is clogged, the compressor works continuously, but there is no cold. Also, if there is a leak, the condenser remains cold, and if clogged, it can heat up, but unevenly.

How much does a new capillary tube cost?

The tube itself costs inexpensive - from 300 to 1,000 rubles. per meter. But the main costs are related to work: soldering, vacuuming, refilling freon. In total, the repair will cost 5,000–10,000 rubles., depending on the refrigerator model.

Is it possible to clean the tube without nitrogen balloon?

Yes, but the efficiency will be lower. You can use:

• 🔌 Powerful compressor (for example, from a spray gun) with pressure up to 10 bar.
• 💨 Car pump with an adapter (but it gives too little pressure).
• 🧹 Special solvents (for example, RC FLUSH), but they require flushing the system.

However, without heating the tube (with a hair dryer or blowtorch) tar deposits will not dissolve.

What will happen if you do not clean the clogged tube?

If you ignore the problem:

• 🔥 The compressor will wear out and will burn out in 3-6 months.
• ⚡ Electricity consumption will increase by 30-50%.
• ❄️ A ice "coat"will appear in the freezer, which will worsen heat transfer.
• 💸 Repair will cost more - you may need to replace the compressor (8,000–15,000 rubles.).