Failure of the cooling circuit is one of the most common causes of failure of household appliances. If you notice oily marks on the tubes or the compressor runs non-stop without cooling the chamber, a microcrack has probably formed. In such a situation, many craftsmen offer expensive repairs with replacement of the evaporator, but experienced users often look for a way to solder the refrigerator tube themselves in order to save budget.
The process of soldering copper tubes requires not only special equipment, but also strict adherence to safety technology. Refrigerant, located in the system can be flammable, and an open fire in a confined space of an apartment creates risks. However, with a competent approach and the availability of a minimum set of tools, it is quite possible even for a beginner to restore the tightness. Freon pipes quite realistic even for a beginner.
In this article we will analyze in detail all the stages of restoring the circuit: from finding a leak to the final check of the seam. You'll learn which solder is best, whether you need to use nitrogen, and why regular tin-lead soldering won't work here. It is important to understand that the success of the operation depends on the cleanliness of the surface and the correct heating temperature.
Finding the leak and preparing for repair
Before touching the burner, it is necessary to accurately localize the problem area. Often it is impossible to visually detect a fistula, especially if it is microscopic. The most reliable way is to use a soap solution or a special spray to find leaks. Apply liberal foam to suspicious joints and bends in the copper line.
If bubbles do not appear, there may be no pressure left in the system. In this case, preliminary nitrogen application will be required. This is a critical step because vacuum soldering is not possible and the presence of air inside will cause the copper to oxidize from the inside. Without removing oxygen and moisture, a high-quality seam will not work. crimping nitrogen. This is a critical step because vacuum soldering is not possible and the presence of air inside will cause the copper to oxidize from the inside. Without removing oxygen and moisture, a high-quality seam will not work.
After identifying the location of the damage, the area must be cleaned. Use fine sandpaper or a special copper brush. The surface should be shiny, free of oxides and dirt. If the tube is damaged by rust or has deep defects over a long distance, soldering may be ineffective - then a new section will need to be inserted.
⚠️ Attention: Before starting any work, make sure that the refrigerator is unplugged and the refrigerant is completely removed from the system in a well-ventilated area or outside.
Preparation of the workplace is also key role. Provide access to the rear wall of the unit and remove flammable objects. If you are working in a garage or workshop, make sure you have a stable support for soldering. It is often more convenient to dismantle the compressor unit or roll out the refrigerator to room to maneuver the burner.
Required tools and materials for soldering
The quality of soldering directly depends on the selected equipment. To work with copper pipes of refrigerators, a conventional gas canister with a camping burner may not be enough, since copper has high thermal conductivity and quickly releases heat. The optimal solution would be to use oxygen-propane or an acetylene torch, which allows you to adjust the torch.
Particular attention should be paid to the choice of solder. Unlike water pipes, the refrigeration circuit operates under pressure and vibration. Regular soft solder with rosin will not work here, as it has a low melting point and insufficient strength. You will need hard silver solder or a phosphorus-copper alloy.
Here is a list of basic materials that should be on hand:
- 🔥 Gas burner with flame regulator and cylinder.
- 🪖 Hard solder (silver-containing or copper-phosphorus).
- 🧹 Flux for soldering copper (if solder without flux in the core is used).
- 🔧 Pipe cutter, rimmer (rimmer removes burrs) and rolling tool.
- 🧤 Heat-protective gloves and glasses.
Flux is necessary to prevent oxidation of the metal during heating and improve the fluidity of the solder. However, if you are using self-fluxing solder (for example, brand HT-2000 or analogues containing phosphorus), additional chemicals may not be required. Phosphorus itself acts as a reducing agent, which simplifies the process and reduces the risk of corrosion in the future.
Brassing technology
The process of connecting pipes itself requires a certain skill. The main rule: it is not the solder itself that needs to be heated, but the parts being connected. When the copper reaches the desired temperature (about 700-750°C), it will melt the solder rod itself, which will flow into the gap due to capillary effect. If you only heat the rod, it will simply drain without ensuring a tight seal.
Heat the pipe evenly, moving the flame in a circle. Do not hold the torch at one point for too long to avoid burning the metal. Once the metal has turned a dark red color (hardened state), apply solder to the joint. If the temperature is selected correctly, the solder will instantly melt and be drawn into the joint.
☑️ Checklist before soldering
After the seam is formed, let it cool naturally. Do not cool the soldering area with water or a damp cloth under any circumstances - a sudden temperature change can lead to the appearance of microcracks in the structure of the metal or the seam itself. The copper must cool slowly to relieve internal stress.
⚠️ Attention: When soldering near plastic elements or a refrigerator, be sure to use a wet cloth or special heat-dissipating clamps so as not to damage the coating.
If you are soldering the joint of two pipes of different diameters (insert), the technology remains the same. It is important to ensure that the pipes are inserted into each other with slight interference. The seating depth must be at least the diameter of the pipe so that the contact area is sufficient to withstand pressure.
Features of working with different metals
Modern refrigerators, especially budget models, often use not pure copper, but copper-coated steel (aluminum is less common in the circuit, but it does happen in evaporators). Soldering steel requires a different approach. Regular copper-phosphorus solder will not work here, since it does not interact with steel properly.
To join copper with steel or brass, it is necessary to use special high-temperature solders containing silver and active fluxes. The melting point of such alloys is higher, which requires more powerful heating. It is important not to overheat the thin wall of the steel tube, otherwise it will burn out.
The table below will help you navigate the choice of materials for different types of connections:
| Type of connection | Recommended solder | Melting point | Do I need flux |
|---|---|---|---|
| Copper - Copper | Copper-phosphorus | ~700°C | No (self-fluxing) |
| Copper - Brass | Silver (30-40% Ag) | ~750°C | Yes (special) |
| Copper - Steel | High silver | ~800°C | Yes (active) |
| Aluminum - Copper | Special. alloy for Al | ~450-500°C | Yes (corrosive) |
Why can’t you solder aluminum with regular solder?
Aluminum instantly oxidizes in air, forming a strong film that regular flux cannot destroy. To solder aluminum, you need either special ultrasonic soldering irons or chemically aggressive fluxes that require thorough rinsing after work, otherwise corrosion will destroy the seam in a few months.
When working with steel pipes, which often go to outlet loops (loops) near the compressor, be prepared for the fact that they will have to be heated longer. Steel conducts heat worse, but also releases it worse, so the risk of local overheating is higher. Move the burner constantly.
Completing work and checking for leaks
After the seam has cooled, it must be cleaned of flux residues. Flux is chemically reactive and if left on the pipe it will continue to react, eventually leading to corrosion and another leak. Wipe the soldering area with a damp cloth or special remover.
The next step is the verification step. Even if the seam looks perfect visually, only crimping can guarantee 100% tightness. Connect a nitrogen cylinder through the reducer and create a pressure of about 10-12 atmospheres in the system. Leave the system under pressure for several hours (preferably a day).
Monitor the pressure gauge readings. If the arrow stays still, you have done it, the circuit is sealed. If the pressure drops, look for the leak again using a soap solution. It often happens that a micro-hole remains unsoldered, noticeable only by the emerging bubbles.
Only after successful pressure testing can the system be evacuated and charged with refrigerant. Soldering without subsequent vacuuming is impossible, since air and moisture will remain in the system, which will damage the compressor.
Common mistakes and safety measures
Beginners often make mistakes that nullify all efforts. The most common one is insufficient heating. The solder lies “snot” on the surface, but does not flow into the gap. This happens because the pipe is cold. You need to heat more actively and longer, but evenly.
Another mistake is using an excessive amount of flux. Excess of it can get inside the tube and clog the capillary system or filter drier. This will cause the refrigerator to stop cooling even though there is no leak. The flux must be applied in a thin layer.
- 🚫 Do not direct the burner flame at adjacent elements of the refrigerator.
- 🚫 Do not leave the burner on unattended for even a second.
- 🚫 Do not touch the newly sealed pipe with your hands - it will cause a burn. guaranteed.
- 🚫 Do not ignore the burning smell - this may indicate melting of the wire insulation.
⚠️ Attention: Some countries have strict environmental regulations for working with refrigerants. The release of freon into the atmosphere may be prohibited by law. Dispose of gas through specialized services.
It is also worth remembering about fire safety. Older refrigerators may use polystyrene foam or other flammable materials as back wall insulation. If the outer tube gets too hot, the heat can transfer to the insulation and cause smoldering or a fire inside the housing. Work carefully and control the body temperature.
When soldering is impossible and you need a master
Despite the apparent simplicity, there are situations when taking on the burner yourself is a bad idea. If the leak occurs in the foamed part of the case (the evaporator inside the freezer), then simply soldering the outside will not help. You will need to open the housing, which will ruin the thermal insulation and aesthetics, or install an external evaporator (“crying”), which is a complex engineering task.
Also, you should not try to repair it yourself if the compressor itself is damaged (a crack in the housing) or if you do not have the ability to create a vacuum and charge the system with the exact amount of refrigerant. Working “by eye” with gas will lead to inefficient operation of the refrigerator.
If you are unsure of your abilities or do not have the necessary equipment for charging, it is better to limit yourself to searching for leaks and dismantling the unit, and entrust the soldering and charging itself to a service center. This will save you nerves and guarantee long-term operation of the equipment.
FAQ: Frequently asked questions
Is it possible to solder a refrigerator tube with ordinary tin solder?
Technically possible, but highly not recommended. Tin-lead solders (PLS) have a low melting point and insufficient strength for compressor vibrations. Over time, such a seam may leak. Use only hard silver or copper-phosphorus solders.
Do you need to remove the compressor to solder the tube?
Not always. If access to the leak site is free and there is room for safe operation of the torch, you can solder on site. However, if the tube comes close to the body or other elements, it is better to remove or bend the compressor so as not to damage the varnish coating and insulation.
What to do if the refrigerator does not freeze after soldering?
Most likely, there is air or moisture left in the system, or the capillary is clogged with flux combustion products. The reason may also be due to improper refrigerant charging. Repeated evacuation and pressure checking are required.
Which solder is better: with silver or copper-phosphorus?
Copper-phosphorus is ideal for joining pure copper with copper (it is cheaper and does not require flux). To connect copper with steel or brass, you definitely need solder with a silver content (from 15% to 40%), since phosphorus solders provide a fragile connection with ferrous metals.