How and how to properly solder tubes in the refrigerator: choice of solder, flux and technology

When the refrigerator stops freezing or signs of freon leakage appear, one of the common reasons is depressurization of the copper pipes of the cooling circuit. Their integrity can be restored using soldering - a process that requires not only skills, but also the right choice of materials. The strength of the seam, the tightness of the system and the durability of the repair depend on it. how the tubes in the refrigerator are soldereddepends on the strength of the seam, the tightness of the system and the durability of the repair.

Unlike soldering electrical wiring or plumbing pipes, working with refrigeration equipment has its own nuances. Here, not only mechanical strength is important, but also chemical resistance connections to refrigerants (for example, R134a, R600a), as well as the absence of internal contaminants that could clog the capillary tube. In this article, we will look at which solders and fluxes are suitable for copper pipes, why you cannot use tin-lead alloys, and how to avoid mistakes when soldering.

It is worth noting right away: if you have never held a soldering iron or torch in your hands, it is better to entrust the repair to a professional. Soldering errors can lead to repeated freon leakage, damage to the compressor or even fire due to flux residues inside the system. But if you are ready to learn, read on.

Why you can’t use regular solder for refrigerators

Many beginners try to solder copper refrigerator tubes with the same solder as for radio components - for example, POS-61 (tin-lead alloy). This is a gross mistake that will result in rapid corrosion of the seam and a new leak. The fact is that:

• 🔬 The refrigerant is aggressive towards lead. Over time, it destroys the seam, forming microcracks.
• 🔥 The melting point of POS-61 (~183°C) is too low. When the refrigerator is running, the tubes heat up and the seam may “float.”
• ⚗️ Acidic residues flux (for example, LTI-120) cause corrosion of copper from the inside, clogging the capillary system.

For refrigeration systems they use copper-phosphorus or silver-containing soldersthat withstand vibrations, temperature changes and do not react with freon. For example, solder CuP6 (6% phosphorus) or Ag5 (5% silver) forms a seam with a tensile strength of up to 250 MPa —this is enough for decades of operation.

Types of solders for copper tubes of a refrigerator: comparison table

The choice of solder depends on the diameter of the tubes, the type of refrigerant and the available equipment. Below is a comparison of the most common options used by refrigerator repair technicians.

For most household refrigerators (Atlant, Indesit, Samsung) the optimal choice becomes Ag5 - it is universal and forgives small mistakes when soldering. If you are repairing industrial equipment with large diameter tubes, it is better to take CuP6 - it is cheaper and stronger.

Fluxes for soldering: which one to choose and why not all are suitable

Flux is necessary to remove the oxide film from copper and improve wettability with solder. However acid fluxes (for example, LTI-120 or F-38N) are strictly prohibited in refrigeration systems! Their residues corrode copper from the inside, and vapors when heated can damage the compressor.

For soldering refrigerator tubes, use neutral or low-active fluxes:

• 🧪 F-38M - based on boric acid, suitable for copper-phosphorus solders.
• 🧴 Castolin Alu-Flux 2000 - universal, does not require rinsing (but expensive).
• 💧 Water with borax - homemade version (10 g of borax per 100 ml of water), but requires careful flushing.

What will happen if you do not wash the flux?

The flux residues inside the tubes react with the compressor oil, forming tarry deposits. This leads to jamming of the compressor or blockage of the capillary tube. In 80% of cases, such repairs end with replacing the compressor after 1–2 years.

After soldering be sure to rinse the seam area hot water with soda (100 g per 1 liter) or a special cleaner (for example, Loctite SF 7063). This will remove flux residues and prevent corrosion.

⚠️ Attention: If you solder tubes with freon residues, use nitrogen purge (a nitrogen cylinder under pressure of 0.5–1 bar). When heated, freon decomposes into toxic gases (for example, phosgene), which can cause poisoning!

Tools for soldering: what is needed besides solder and flux

For high-quality soldering of refrigerator tubes, solder alone is not enough. You will need:

1. A burner or blowtorch —preferably a gas one with piezo ignition (for example, Rothenberger Super Fire 2). The power should be at least 1.5 kWto evenly heat a tube with a diameter of 6–10 mm.
2. Pipe cutter and chamfer - for neat cutting of tubes without burrs. Cheap roller pipe cutters often crush copper!
3. Flaring machine - if you need to connect tubes without soldering (for example, when replacing a filter drier).
4. Nitrogen cylinder with a reducer - for purging the system before soldering (removes moisture and freon residues).
5. Leak detector —electronic (for example, Inficon D-Tek Select) or soap solution to check the tightness.

Do not skimp on the burner: cheap Chinese models often overheat copper, which leads to metal annealing (the tube becomes brittle). The best option is a burner with flame control, for example Kemper Profil 2000.

Disconnect the refrigerator from the mains and discharge the capacitors|Drain the freon into the cylinder (if the system is filled)|Blow the system with nitrogen (pressure 0.5–1 bar)|Clean the soldering area with sandpaper (grain 120–240)|Apply a thin layer of flux with a brush-->

Step-by-step instructions: how to solder refrigerator tubes

Before starting work required put on safety glasses and gloves - splashes of molten solder can cause burns. Follow the algorithm:

1. Preparation:

   Cut the damaged area with a pipe cutter, remove burrs with a chamfer. The soldering area must be clean - free of oxides and grease (wipe with acetone).

2. Assembling the joint:

   Insert the tubes into each other (the gap is no more 0.1 mm) or use coupling (for tubes of different diameters). Secure the joint clamp or heat-resistant tape to avoid displacement.

3. Application of flux:

   Use a brush to apply a thin layer of flux to the soldering area. Avoid excess - it can flow inside the tube.

4. Heating and soldering:

   Heat the joint evenly with a torch (the flame should cover the tube 20–30 mm around the seam). When the copper turns red (about 700°C), bring a solder rod. It should melt from the heat of the tube, not the burner!

5. Cooling and checking:

   Allow the seam to cool naturally (do not cool with water!). Rinse the soldering area with water and soda. Check the tightness with a leak detector or soap solution (pump nitrogen to 10–15 bar).

If the seam is porous or cracked, re-solder it. Do not try to “cover up” the defects with additional solder - this is a temporary solution that will lead to repeated leakage.

Typical mistakes and how to avoid them

Even experienced craftsmen sometimes make mistakes that negate the entire repair. Here are the most common ones:

• 🔥 Overheating of the tube - copper becomes brittle, and solder “leaks” inside, clogging. capillary. Solution: use a torch with flame adjustment and do not hold it in one place for more than 10 seconds.
• 💦 Moisture entering the system — when soldering without nitrogen purge, moisture from the air condenses inside tubes. Solution: always purge the system with nitrogen before soldering (pressure 0.5 bar).
• 🧲 Use of magnetic solders —some cheap alloys contain iron, which attracts metal shavings. Solution: buy solders from trusted brands (Harris, Lucas-Milhaupt).
• 🔧 Soldering under pressure - if there is freon left in the system, it can explode when heated. Solution: always bleed off the refrigerant before repairs!

Another common problem is "false tightness"The seam may not leak when tested with nitrogen, but begin to leak freon under it. operating pressure. To avoid this, after soldering:

1. Fill the system with nitrogen to 25–30 bar (maximum operating pressure of the refrigerator).
2. Leave for 12–24 hours.
3. Check the pressure with a pressure gauge - if it drops, look for a leak.

⚠️ Attention: If you solder refrigerator tubes with with an inverter compressor (for example, Samsung Digital Inverter or LG Linear, be sure to disconnect the control board! Solder splashes or overheating can damage it. It is better to remove the board before soldering.

How to solder aluminum tubes (if yours has them). refrigerator)

In most modern refrigerators, the tubes are made of copper, but in some budget models (for example, Birusa or old Zanussis) you can find aluminum. Soldering aluminum is a more difficult task, since it oxidizes quickly and has a low melting point (660°C).

For). aluminum tubes are suitable:

• 🔧 Solder Alu-Solder —a special alloy based on zinc and tin (for example, Harris Stay-Silv 15).
• 🧪 Flux Castolin Alu-Flux —removes the oxide film and prevents its re-formation.

Aluminum soldering technology:

1. Clean the soldering area with a metal brush (not sandpaper!).
2. Apply flux and immediately start heating - aluminum oxidizes in seconds!
3. Use powerful burner (from 2 kW), since aluminum removes heat well.
4. After soldering do not rinse the seam with water —the flux for aluminum is not aggressive and does not require rinsing.

If you do not have experience in soldering aluminum, it is better to replace the aluminum tube with a copper one using bimetallic coupling (for example, K64 from Rothenberger). It is more reliable and simpler.

FAQ: Frequently asked questions about soldering refrigerator tubes

Is it possible to solder refrigerator tubes with a regular soldering iron?

No, the power of a regular soldering iron (60–100 W) is not enough to heat copper tubes 0.8–1.2 mm thick. In addition, the soldering iron does not provide uniform heating, which leads to “cold” seams. burner with a power of 1.5 kW.

Which solder is better: copper-phosphorus or silver-containing?

Silver-containing solder (Ag5) is more universal: it is more flexible, fills gaps better and is suitable for any refrigerants. Copper-phosphorus (CuP6) is cheaper and stronger, but is fragile due to vibrations Ag5, for industrial systems - CuP6.

What to do if the refrigerator does not freeze after soldering?

There may be several reasons:

1. Clogged capillary tube - flux residues or scale have entered the system. Solution: rinse the system with a solvent (R141b) and blow out nitrogen.
2. Lack of freon - during soldering, part of the refrigerant could evaporate. Solution: fill the refrigerator according to the pressure gauge (suction pressure for R134a — about 0.1 MPa).
3. The compressor is damaged —if soldering was carried out without nitrogen purge, moisture could get into the oil. Solution: replace the oil and filter drier.

Is it possible to use solder with cadmium for refrigerators?

No, Cadmium is toxic, and it is not! vapors can get into products. In addition, cadmium solders are fragile and cannot withstand compressor vibrations. In the EU and Russia, such solders are prohibited for household appliances.

How much does it cost to repair refrigerator tubes in the service?

The cost depends on the complexity of the work:

• 🔧 Sealing one crack - from 1500 to 3000 rubles.
• 🔄 Replacement of a section of the tube (up to 30 cm) - from 3000 to 5000 rubles.
• 🔄 Replacement of the capillary tubes - from 5000 to 8000 rubles.
• ⚙️ Complete re-soldering of the circuit (for corrosion) - from 10,000 rubles.

Prices are relevant for Moscow and regions for 2026. The price usually includes work, but not always materials (solder, flux, nitrogen). Check before repair!