When the refrigerator stops working freeze, and the compressor hums non-stop, the problem often lies in a refrigerant leak through cracks in the copper tubes. Soldering is the only reliable way to restore the tightness of the system, but not every solder is suitable for this task. Copper tubes of refrigerators operate under pressure, come into contact with aggressive refrigerants (R134a, R600a) and must withstand temperature changes from -30°C to +100°C. An error in choosing a material or soldering technology will lead to a second leak within a few months.
In this article, we will look at which ones professionals use to repair refrigeration systems, why tin ones are preferable, and how to avoid typical mistakes when soldering at home. You will also find out whether it is possible to solder pipes solders and fluxes used by professionals to repair refrigeration systems, why phosphorus-copper alloys preferable to tin, and how to avoid common mistakes when soldering at home. You will also find out whether it is possible to solder tubes inverter refrigerators (for example, Samsung No Frost or LG DoorCooling+) and how this differs from repairing classic models.
Why you can’t use regular tin solder
Many home craftsmen try to solder copper refrigerator tubes POS-61 or other tin-lead solders - this is a gross mistake. Such alloys have three critical disadvantages:
- 🔥 Low melting point (180–230°C). When the compressor operates, the tubes heat up to 80–90°C, and in the soldering zone the tin solder begins to “creep”, losing its tightness.
- ⚗️ Chemical instability. Refrigerants (especially R600a isobutane) and compressor oils corrode tin seams in 1–2 years.
- 💥 Weak mechanical strength. Vibrations from the compressor quickly destroy the soft seam, especially in places where the tubes are bent.
The exception is temporary repairs of old Soviet refrigerators (ZIL, Minsk), where the pressure in the system is lower and the refrigerant (R12) is less aggressive. But even in this case, the tin seam will last no more than 3–5 years.
⚠️ Attention: If you have already soldered the POS-61 tubes and the system holds pressure, do not relax. Under load, such a seam may burst within a few months, releasing all the freon. Use only specialized solders!
Types of solders for copper refrigerator tubes
For soldering refrigeration systems, three types of solders are used, each of which has its own pros and cons. The choice depends on type of refrigerant, tube material (pure copper or coated) and equipment availability.
| Type of solder | Composition | Melting point, °C | Advantages | Disadvantages |
|---|---|---|---|---|
| Phosphorus-copper (Cu-P) | 92–95% Cu, 5–8% P | 640–750 | High strength, resistance to refrigerants, does not require flux for copper | Brittility at low temperatures, not suitable for brass |
| Silver (Ag-Cu-Zn) | 40–60% Ag, the rest Cu and Zn | 600–800 | Versatility, weld ductility, suitable for all metals | High price, requires flux |
| Copper-zinc (Cu-Zn) | 50–60% Cu, 40–50% Zn | 800–900 | Cheap, good fluidity | Requires a powerful burner, the seam is prone to corrosion |
For most modern refrigerators (Atlant, Indesit, Beko) is optimal phosphorus-copper solder brands Castolin 192 FB or Harris Stay-Brite. It forms a strong seam, resistant to R134a i R600aand does not require flux when soldering pure copper. Silver solders (Castolin 190, Lucas-Milhaupt Sil-Fos) are used for repairing coated tubes or in critical assemblies (for example, at the point where a capillary tube is attached).
Technology soldering: step-by-step instructions
Before soldering, you must completely remove any remaining refrigerant from the system (you cannot pierce the tube - it is dangerous!). To do this, use vacuum pump or flush the system with nitrogen. Work is carried out in a well-ventilated area with fire extinguishing equipment at hand.
Drain the refrigerant into the cylinder|Clean the soldering area with sandpaper|Degrease the tubes with acetone|Prepare solder and torch|Wear safety glasses and gloves-->
The soldering process itself includes the following steps:
- Heating the tubes. Use propane-butane torch with a narrow flame. Heat the joint evenly, avoiding overheating (copper should not turn red).
- Application of flux (if required). For silver solders, use flux Harris Stay-Silv or Castolin Flux 2000. Phosphorus-copper solder does not require flux.
- Soldering. Apply solder to the joint - it should melt from the heat of the tubes, not the torch. Distribute the melt evenly over the seam.
- Cooling. Allow the seam to cool naturally. Do not cool with water - this will lead to microcracks!
After soldering, be sure to check the tightness of the seam soap solution under a pressure of 10–15 atm. If there are no bubbles, the system can be charged with refrigerant.
Errors that lead to repeated leakage
Even experienced craftsmen sometimes make mistakes that cause the solder seam to fail will depressurize in a few weeks. Here are the most common mistakes:
- 🔥 Overheating of the tubes. If the copper is heated to red, its structure becomes porous and the seam does not hold pressure.
- 💧 Use of water for cooling. A sharp temperature change creates microcracks in the solder.
- 🧴 Saving on flux. Cheap fluxes (for example, rosin) do not remove oxides from copper, and the solder does not “stick” to the surface.
- 🔧 Soldering dirty pipes. Residues of oil, paint or oxides prevent the solder from adhering to the metal.
- ⚖️ Insufficient heating. If the tubes are weakly heated, the solder will not flow into the gap, and the seam will be porous.
A critical mistake is soldering the tubes under refrigerant pressure. Even if you managed to “grab” the crack without draining the freon, when heated, the pressure in the system will increase, and the tube may burst right in your hands! Always bleed off the refrigerant before repairs.
⚠️ Attention: If you solder refrigerator tubes with with an inverter compressor (Samsung Digital Inverter, LG Smart Inverter, be sure to disconnect the control board while working. Voltage drops when the burner is turned on can burn the electronics!
How to solder tubes in refrigerators with different refrigerants
The type of refrigerant directly affects the choice of solder. The fact is that some freons (R600a, R290) are chemically active and corrode unsuitable alloys. Below are recommendations for the most common refrigerants:
- ❄️ R134a (used in Atlant, Indesit, Stinol). Any phosphorus-copper or silver solder will do. The main thing is to thoroughly clean the soldering area from oil.
- 🔥 R600a (isobutane, used in Samsung, LG, Liebert). Requires only silver solders (for example, Castolin 190) or special copper-phosphorus alloys with silver additives. Regular Cu-P solder will last no more than a year.
- 🧪 R290 (propane, used in industrial refrigerators). Aggressive to all solders, except high-silver ones (Lucas-Milhaupt Easy-Flo 45). Soldering must be performed by a certified specialist.
- ⚡ R410a (found in some models Haier i Hisense). Requires solders with a melting point above 700°C, as it operates under high pressure (up to 30 atm).
If you are not sure what refrigerant is used in your refrigerator, look nameplate on the compressor or in the technical data sheet. The designation usually begins with a letter. is missing, pay attention to: R (For example, R134a or R600a).
How to determine the type of refrigerant without a nameplate?
If the nameplate is worn out or missing, pay attention to:
1. The color of the oil in the compressor: for R134a yellow or green oil is used, for R600a - colorless.
2. Tube diameter: systems s R600a have thicker tubes (6–8 mm), since isobutane is less efficient in heat transfer.
3. Refrigerator brand: budget models (Beko, Pozis) almost always work on R600a, and premium ones (Liebherr, Miele) - on R134a or R410a.
Soldering of tubes in No Frost refrigerators
Systems No Frost (used in Samsung, LG, Bosch) have two key features that complicate soldering:
- Thin capillary tubes (diameter 1–2 mm). They are easy to overheat or melt if not handled carefully.
- Presence of electronics near the evaporator. The defrost board or fan may be damaged by an open flame.
To repair such systems, follow the rules:
- 🔧 Use microtorch with an adjustable flame or soldering station with precise temperature adjustment.
- 🛡️ Shield adjacent parts asbestos sheet or ceramic tiles.
- 🧲 For capillary tubes, use low temperature silver solders (Castolin 191) with a melting point of 600–650°C.
- 🔍 Before soldering, check the tubes for internal blockages - in systems No Frost moisture and oil often accumulate.
Be sure to check after repair work evaporator fan i defrosting heating element. If the electronics have been damaged by heat, the refrigerator may turn on, but will not freeze.
Alternative methods for repairing pipes
Soldering is not the only way to restore the tightness of the system. In some cases, it is more appropriate to use alternative methods:
| Method | When to use | Pros | Cons |
|---|---|---|---|
| Clamps with rubber gasket | Temporary repair of small cracks (up to 1 mm) | Fast, does not require heating | Unreliable, suitable only for low pressure |
| Epoxy resin | Cracks in inaccessible places (for example, behind foam) | No need to solder | Resin may peel off over time |
| Replacement of the tube section | Severe corrosion damage | Reliable, like new | Requires welding equipment |
| Brass fittings | Repair at joints (for example, filter drier) | Simple, does not require high qualifications | Increases flow resistance refrigerant |
Clamps and epoxy can only be considered temporary solution for 1–3 months. For a complete repair, soldering or replacing the tubes is necessary. If the crack is located in foam part of the body, sometimes it is easier to drill a hole in the foam than trying to get to the tube through standard hatches.
FAQ: Frequently asked questions about soldering tubes refrigerator
Is it possible to solder refrigerator tubes with a regular soldering iron?
No, the power of a standard soldering iron (40–60 W) is not enough to heat copper tubes to the melting temperature of solder (600–900°C). For soldering, use propane-butane torch or gas torch with oxygen (for example, Kemper 2000). An exception is the soldering of thin capillary tubes (diameter up to 2 mm), where you can use soldering station a power of 100–150 W with a tube attachment.
Which flux is best for soldering copper tubes?
For phosphorus-copper solders, no flux is required (if you are soldering pure copper). For silver solders, use:
- Harris Stay-Silv White — universal flux for copper and brass, does not require rinsing.
- Castolin Flux 2000 —suitable for high-temperature soldering (up to 900°C).
- Lucas-Milhaupt Handy Flux —gel flux, convenient for vertical seams.
How much does it cost to repair refrigerator tubes in the service?
The cost depends on the complexity of the work:
- Soldering one crack — 1500–3000 rubles.
- Replacement of a section of the tube — 3000–5000 rub.
- Repair in the No Frost system — 4000–7000 rub. (due to the difficulty of access).
- Full recharge with refrigerant — 2000–4000 rubles. (depending on the type of freon).
⚠️ Prices may vary depending on the region and model of the refrigerator. In Moscow and St. Petersburg, repairs are 20–30% more expensive than in the regions.
Is it possible to solder aluminum tubes in a refrigerator?
Aluminum tubes (found in some models Haier and Vestfrost) soldering is much more difficult than copper ones. For this you need:
- Special solders zinc-based (Castolin 196) or aluminum (Aluminum Solder).
- Flux for aluminum (Harris Aluma-Flux).
- Powerful burner (aluminum requires heating to 500–600°C).
It is not recommended to solder aluminum without experience - the seam will be fragile. In services, such tubes are usually replaced with copper ones or use mechanical connectors.
What what to do if after soldering the refrigerator does not freeze?
If the compressor is working, but there is no cold, check:
- Seam tightness - apply a soap solution, if there are bubbles, resolder.
- Refrigerant charging - perhaps there is not enough freon (needs to be refilled).
- Filter drier - during soldering it could become clogged (replacement is required).
- Capillary tube - if it is clogged, the refrigerant does not circulate (need to be purged with nitrogen).
- Electronics —if the control board is burned out from overheating, the refrigerator will not freeze even with a working system.
The most common reason is insufficient vacuum before refueling. Moisture remains in the system, which freezes in the capillary tube and blocks the flow of freon.