Soldering copper pipes of a refrigerator: a complete guide for DIY repairs

When the refrigerator stops freezing and the compressor runs non-stop, the problem often lies in a freon leak. The main reason is cracks or breakdowns in the copper tubes of the circuit. In 80% of cases, such a malfunction can be eliminated independently, if correctly solder the damaged area. However, soldering copper in refrigeration equipment has nuances: not only the skills of working with a soldering iron are important here, but also the choice of materials compatible with the refrigerant, as well as maintaining the tightness of the system.

In this article you will find step-by-step instructions for soldering copper tubes taking into account specifics of refrigeration systems, recommendations for choosing solder and flux, as well as critical errors that lead to repeated leaks through 1–2 months after repair. The material is aimed at novice craftsmen, but will also be useful for experienced repairmen - we have collected current data on modern refrigerants (R134a, R600a, R290) and the features of their interaction with solders.

Before you start work, make sure that the problem is in the tubes: check for the presence of oil at the site of the suspected leak (freon leaves along with the compressor oil), listen to the hissing when turned on (a characteristic sound for large breakdowns) or use leak detector. If the diagnosis is confirmed, we begin the repair.

1. Tools and materials: what you will need for soldering

For high-quality soldering of copper refrigerator tubes, an ordinary soldering iron is not enough. You will need specialized equipment and consumables that can withstand the pressure in the system (up to 15 atm) and do not react with the refrigerant. Here is the complete list:

• 🔧 Gas torch with adjustable flame (propane-butane or acetylene). Power - at least 1 kW. Electric soldering irons are not suitable due to insufficient heating temperature.
• 🧲 Solder based on silver (brand POS-61, POS-40) or copper-phosphorus (CuP-6). Ordinary lead-tin solder (POS-60) is strictly prohibited - it does not withstand compressor vibrations.
• 🧪 Flux for copper (for example, F-SW21 or Castolin 190F). It removes the oxide film and prevents the formation of scale. Rosin or acid fluxes will not work!
• 🧰 Pipe cutter or a hacksaw for metal to carefully trim the damaged area.
• 🔨 File and scraper for stripping edges of the tubes.
• 🧴 Nitrogen (in a cylinder) for purging the system before soldering - required when working with modern refrigerants (R600a, R290).
• 🛠️ Gauge manifold for checking tightness after repair.
• 🧤 Protective gloves i glasses — when copper is heated, toxic fumes are released.

The cost of a complete set of tools for a one-time repair may seem high (from 5-7 thousand rubles), but it is still cheaper than replacing tubes in a service center (price starts from 10 thousand). If you plan to solder tubes regularly, pay attention to professional torches with piezo ignition (for example, Rothenberger Super Fire 2) - they simplify work in hard-to-reach areas. places.

⚠️ Attention: Solder with a silver content of less than 2% does not provide sufficient strength to the seam. For refrigerators with refrigerant R600a (isobutane), be sure to use copper-phosphorus solder - it does not contain zinc, which reacts with hydrocarbons.

2. Preparing tubes for soldering: cleaning and degreasing

The quality of soldering depends 70% on surface preparation. Copper quickly oxidizes in air, and remaining oil or dirt leads to lack of penetration microcracks through which freon will escape again. tubes:

1. Cutting the damaged area. Move 1-2 cm away from the leak site and cut the tube with a pipe cutter. If you use a hacksaw, be sure to remove the burrs with a file.
2. Cleaning the edges. Use scraper or sandpaper (grit 120–180) to remove the oxide film. The surface should be shiny.
3. Degreasing. Wipe the tubes acetone or with a special degreaser (Loctite 7063). Do not use gasoline or alcohol - they leave a film.
4. Applying flux. Use a brush to evenly cover the soldering area with flux, remove excess with a napkin - when heated, they can flow inside the tube and clog the capillary.

If the crack is small (up to 0.5 mm), you can do without trimming - just widen it with a scraper and fill it with solder. However, such a repair is less reliable: when the compressor vibrates, the seam may crumble. For reliability, we recommend insert an insert (a piece of the same copper tube). diameter) or use coupling.

Cut the damaged area with a pipe cutter

Clean the edges until shiny with a scraper

Degrease the surface acetone

Apply a thin layer of flux

Purge the system with nitrogen (when working with R600a/R290)-->

3. Soldering technique: step-by-step process with photos

Soldering copper tubes refrigerator differs from conventional soldering of electrical wiring. Temperature control is also critical here - overheating of copper leads to annealing (loss of strength), and insufficient heating leads to a cold junction. Follow this algorithm: Uniform heat distribution uniform heat distribution and temperature control - overheating of copper leads to its annealing (loss of strength), and insufficient heating leads to a cold junction. Follow this algorithm:

Step 1. Assembling the connection. Insert the tubes into each other (or use coupling) so that the gap between them is 0.1–0.2 mm. If the gap is larger, the solder will not flow inside and the seam will be weak. For fixation, you can use clamps or heat-resistant tape.

Step 2. Heating with a torch. Direct the flame to the joint and heat evenly, rotating the tube. The optimal temperature for copper-phosphorus solder is 700-800°C, for silver - 600-700°C. Focus on the color of the copper: when heated correctly, it becomes. cherry red.

Step 3. Introducing solder. Once the copper is heated, bring the solder rod to the seam. It should melt from the heat of the tube, and not from the direct flame of the burner! Move the solder along the seam, filling it completely, then remove the excess. cooling.

Step 4. Cooling. Allow the seam to cool naturally (do not cool with water!) After cooling, microcracks form in the metal, wipe the seam with a cloth soaked in acetone to remove any remaining flux.

For soldering in in hard-to-reach places (for example, near the compressor) use mirror or a flexible device for directing the flame. Do not allow nearby parts to overheat - plastic elements may melt and rubber seals will lose elasticity.

1) Is the surface sufficiently cleaned (repeat cleaning).

2) Is the temperature sufficient (increase the flame or use a more powerful burner).

3) Is the flux selected correctly (for R600a you need flux without acids).-->

4. Checking the tightness: how to find a leak after soldering

Even a seemingly perfect seam can have microcracks. Before refilling freon, be sure to check the system for leaks. To do this, use nitrogen at a pressure of 15–20 atm (exceeds the operating pressure of the refrigerator). Here's how to do it:

1. Connect gauge manifold to the service port of the compressor.
2. Open the valve of the nitrogen cylinder and pump gas into the system to pressure 15 atm.
3. Close the valve and watch the pressure gauge for 10–15 minutes. A pressure drop of more than 0.5 atm indicates a leak.
4. If the pressure is stable, apply soap solution to all soldered areas. Bubbles will indicate the location of the leak.

To accurately detect microcracks, use electronic leak detector (for example, Inficon D-Tek Select). It reacts to refrigerant or nitrogen vapors. If a leak is not found, but the pressure drops, check:

• 🔍 Schrader valve at the service port - it can let gas through.
• 🔍 Soldering places of the capillary tube - microcracks often form there.
• 🔍 Connection of the compressor with the tube - vibration can break the seal.

⚠️ Attention: If after soldering you find a leak 1-2 days later, most likely the problem is in flux quality (it could clog the capillary) or in insufficient heating suture. In this case, you will have to resolder the connection again.

5. Refilling freon: nuances for different refrigerants

After successful soldering and checking the tightness, you can refill the system with refrigerant. Here it is important to take into account the type of freon, since the pressure in the system and the filling method depend on it:

• 🧊 R134a (tetrafluoroethane) - refilled in the liquid phase through the service port. Suction pressure: 0.1–0.3 atm, discharge: 8–12 atm.
• 🔥 R600a (isobutane) is a flammable gas and requires special care. It is refilled in a vapor state. Suction pressure: 0.05–0.1 atm, discharge: 4–6 atm.
• 🌿 R290 (propane) - also flammable, but more environmentally friendly. Refilling parameters are similar to R600a.

For refueling you will need:

• 🧪 Freon cylinder (volume depends on the refrigerator model, usually 30–100 g).
• 🔧 Manometric manifold with hoses.
• 🌡️ Thermometer for monitoring the temperature at the outlet of the evaporator.

Step-by-step filling process:

1. Connect the manifold to the service port and the cylinder with freon.
2. Open the cylinder valve and bleed the air from the hose (1–2 seconds).
3. Start the refrigerator compressor in cooling mode.
4. Slowly open the manifold valve, monitoring the pressure using the pressure gauge.
5. Fill freon in portions of 10–15 g, checking the temperature at the evaporator outlet (should be −5…−10°C).
6. After refueling, close the valve and check the operation of the refrigerator for 30 minutes.

If after refueling the compressor runs without stopping and the temperature in the chamber does not drop, two problems are possible:

• 🔹 Underfilling - add freon in small portions.
• 🔹 Clogging of the capillary —purging with nitrogen or replacing the capillary tube is required.

⚠️ Attention: When working with R600a i R290 ensure good ventilation of the room - these gases are heavier than air and accumulate below, creating a risk of explosion. Do not smoke or use open fire nearby!

How to check the amount of freon without a pressure gauge?

If there is no pressure gauge, you can focus on the temperature of the condenser (the grill on the back wall of the refrigerator). With proper charging:

- The upper part of the condenser should be hot (50–60°C).

- The lower part should be warm (30–40°C).

- If the condenser is cold, there is too much freon.

- If it is completely hot, there is not enough freon.

This method is approximate and is only suitable for diagnostics, not for precise refueling!

6. Typical mistakes and how to avoid them

Even experienced craftsmen sometimes make mistakes when soldering copper tubes of a refrigerator. Here are the most common of them and ways to prevent them:

Another common mistake is ignoring nitrogen purge before soldering. Refrigerant and oil remain in the tubes, which can ignite when heated by a burner (especially dangerous for R600a and R290). Always purge the system with nitrogen for 5-10 minutes before soldering!

If after repair the refrigerator is unstable (it turns on and off), check:

• 🔹 Freon pressure - perhaps there is too much or not enough of it.
• 🔹 Thermoregulator operation —it could fail due to overheating.
• 🔹 Condition of the capillary tube —during soldering it could become clogged.

7. Alternative Repair Methods: When Soldering Won't Work

Soldering is not the only way to fix leaks in copper tubing. In some cases, it is more appropriate to use alternative methods:

• 🔧 Mechanical couplings. Suitable for temporary repairs or if soldering is not possible (for example, near plastic parts). Couplings Swagelok or Parker withstand pressure up to 50 atm, but require precise fitting of the tubes.
• 🔧 Epoxy compounds. Special two-component adhesives (for example, Loctite Hysol 9466) can seal microcracks, but cannot withstand high pressures. Suitable only for low pressure tubes (suction line).
• 🔧 Replacement of the tube section. If the damage is large (more than 2 cm), it is easier to cut out the defective area and solder a new piece of tube of the same diameter.

Mechanical couplings are convenient because they do not require heating, but they have two disadvantages:

1. They increase resistance to freon flow, which can lead to overheating of the compressor.
2. Over time they weaken due to vibration (especially in refrigerators with linear compressors).

Epoxy compounds are always temporary solution. They cannot withstand prolonged stress and may crumble after 6–12 months. Use them only as a last resort, if there are no other options.

If the leak occurs in the foamed part of the tube (for example, in the wall of a refrigerator), soldering without opening the case is impossible. In this case, you will have to:

1. Carefully open the polyurethane foam layer (use a heated knife or a special cutter).
2. Solder the tube as described above.
3. Fill the cavity polyurethane foam (for example Soudal PU Foam) and restore thermal insulation.

⚠️ Attention: When polyurethane foam is opened, toxic gases are released. Work in a respirator and a ventilated area! After repair, check the tightness of the case - the cracks will lead to the formation of condensation and corrosion.

FAQ: Answers to frequently asked questions

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

No, a regular one a soldering iron (up to 100 W) does not provide sufficient temperature for soldering copper tubes. For a high-quality seam, you need a gas burner with a flame temperature of at least 1000°C. An exception is soldering thin capillary tubes (up to 2 mm in diameter), but even here a powerful soldering iron (200 W+) with a copper tip is required.

Which solder is better: silver or copper-phosphorus?

The choice depends on the refrigerant:

• For R134a both silver (POS-61) and copper-phosphorus (CuP-6) solder are suitable.
• For R600a i R290 copper-phosphorus solder is required - it does not contain zinc, which reacts with hydrocarbons.

Silver solder produces a more ductile seam, but is more expensive. Copper-phosphorus is cheaper and stronger, but requires a higher soldering temperature.

How much does it cost to repair tubes in a service center?

The cost depends on the complexity of the work:

• Soldering one crack - from 3,000 to 6,000 rubles.
• Replacement of a section of the tube - from 5,000 to 10,000 rubles.
• Refilling freon - from 1,500 to 3,000 rubles (depending on the type of refrigerant).

In total, repairs cost 7,000–15,000 rubles Self-repair will be cheaper (2,000–4,000 rubles for materials), but requires skills.

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

There may be several reasons:

1. Not enough freon —check the pressure with a pressure gauge and add refrigerant.
2. Clogged capillary tube —purge the system with nitrogen or replace the capillary.
3. Compressor malfunction —check the resistance of the windings (should be 20–40 Ohms).
4. Airing of the system —vacuum the system for 20-30 minutes before refueling.

If the problem persists, the tube may have overheated during soldering and it has become clogged inside. In this case, you will have to cut out the area and solder it again.

Is it possible to use glue instead of soldering?

Glue (even specialized ones, like Loctite) is a temporary solution. It can seal microcracks for 1–2 months, but does not withstand:

• High pressure (more than 10 atm).
• Compressor vibrations.
• Temperature changes.

The glue is suitable only for emergency repair if it is not possible to solder the tube. After using it, soldering will still be required.