When the refrigerator stops freezing, one of the common reasons is freon leakage through cracks or corrosion in the copper tubes. The tightness of the system can only be restored with the help of high-quality soldering, but here it is important not just to “fill up” the hole, but to create a connection that will withstand the refrigerant pressure and vibration of the compressor. Errors at this stage lead to repeated leaks, overheating of the motor and even a fire.
In this article we will look at how they differ from conventional plumbing materials, and why some “folk” methods (for example, soldering with tin without flux) are categorically not suitable. We will also give step-by-step instructions taking into account the specifics of refrigeration systems - from surface preparation to leak testing. If you have never held a torch in your hands, it is better to entrust the work to a professional: what solder and flux to choose for soldering refrigerator tubes, how they differ from conventional plumbing materials, and why some “folk” methods (for example, soldering with tin without flux) are absolutely not suitable. We will also give step-by-step instructions taking into account the specifics of refrigeration systems - from surface preparation to leak testing. If you have never held a burner in your hands, it is better to entrust the work to a professional: poor quality soldering of refrigerator tubes can result in a capacitor explosion or freon poisoning.
Why you can’t solder refrigerator tubes with regular solder
Copper tubes in the refrigerator operate under extreme conditions: temperature changes from –30°C to +120°C, constant vibration from the compressor, freon pressure up to 15 atmospheres. Conventional POS-61 solder (tin-lead), which is used for soldering radio components or plumbing, is not suitable here for three reasons:
- 🔥 Low melting point (180–200°C): when the tubes are heated with freon or a compressor, the seam may “float”, which will lead to leakage.
- 🛠️ Weak mechanical strength: vibrations will quickly destroy the soft tin seam.
- 🧪 Chemical incompatibility: lead in the solder reacts with oil and freon, clogging the capillary tube.
For refrigeration systems they use refractory solders based on copper, silver or phosphoruswhich form a connection close in strength to the whole tube. For example, CuP6 solder (copper-phosphorus) withstands pressure up to 30 atmospheres and does not require flux for copper, and silver solders (for example, Castolin 192 FBK) provide tightness even with microcracks.
⚠️ Attention: If you are soldering aluminum tubes (found in some models Samsung or LG before 2015), Copper-phosphorus solder will not work - it does not adhere to aluminum. Here you need a specialized solder for aluminum (for example, Aluminum 13) and active flux.
Comparison of solders for soldering refrigeration tubes
The choice of solder depends on the material of the tubes, damage diameter and refrigerant type. Below is a table with the characteristics of the most reliable options:
| Solder type | Composition | Melting point, °C | Connection strength | Suitable for | Cons |
|---|---|---|---|---|---|
| CuP6 (copper-phosphorus) | 94% Cu, 6% P | 700–800 | High (up to 250 MPa) | Copper tubes, small cracks | Does not solder aluminum, brittle when overheated |
| Castolin 192 FBK (silver) | 56% Ag, 22% Cu, 17% Zn, 5% Sn | 630–680 | Very high (up to 300 MPa) | All types of copper, aluminum with flux | Expensive, requires precise heating |
| S-Sn97Cu3 (tin-copper) | 97% Sn, 3% Cu | 227–240 | Medium (up to 70 MPa) | Temporary repair, soldering iron | Unacceptable for permanent use |
| Aluminum 13 | 92% Zn, 8% Al | 380–420 | High (up to 180 MPa) | Aluminum tubes | Requires active flux, toxic fumes |
For most household refrigerators (Atlant, Indesit, Beko) it is optimal CuP6 —it is cheap, easy to use and does not require flux for copper. Silver solders (Castolin, Harris Stay-Silv) are used for industrial systems or if aluminum needs to be soldered. Tin solders (POS-61, S-Sn97Cu3) are acceptable only for temporary repairs followed by replacement of the tube.
Fluxes for soldering: which one to choose and why
Flux removes the oxide film from the metal surface, ensuring uniform spreading solder. Suitable for refrigerator copper tubes:
- 🧴 Boric acid in paste (Flux F-38N): universal option for copper-phosphorus solders. Does not require washing, but leaves a white coating.
- 🔬 Flux paste Harris Stay-Clean: based on fluoroborates, suitable for silver solders. Active at high temperatures.
- ⚗️ Liquid flux Tenacity No. 5: for soldering aluminum and stainless steel. Contains aggressive acids - requires washing!
❌ What should not be used:
- 🚫 Rosin or alcohol-rosin flux: does not remove copper oxides at high temperatures.
- 🚫 Soldering acid (HCl): corrodes copper, leads to corrosion seam.
- 🚫 Fluxes for soldering radio components (LTI-120): not designed for freon pressure.
For CuP6 flux is often not needed (copper self-fluxes when heated), but if the tubes are heavily oxidized, it is better to use F-38N. For silver solders, fluoroborate-based flux is required (Harris Stay-Clean), otherwise the solder will not spread.
Step-by-step instructions: how to solder refrigerator tubes
Before starting work unplug the refrigeratorbleed off the freon (if the system is charged) and remove the damaged tube. For soldering you will need:
- 🔥 Propane torch with a narrow flame (for example, Rothenberger Super Fire).
- 🛠️ Solder (CuP6 or silver).
- 🧴 Flux (if needed).
- 🧊 Rag and water for cooling.
- 👓 Safety glasses and gloves.
Sand the tube with sandpaper (grain 120–240)|Degrease the surface acetone or alcohol|Apply flux (if required)|Prepare solder and torch|Ensure room ventilation-->
Step 1. Cleaning and preparation
Remove oxides from the soldering area with sandpaper or a metal brush Wipe the tube with acetone - grease or dirt. will prevent the solder from adhering. If you are soldering aluminum, use Tenacity No. 5 and immediately apply it with a brush.
Step 2. Heating the tube
Turn on the burner and heat the tube on the opposite side from the soldering siteso that the heat is distributed evenly. For CuP6 you need a temperature of ~750°C (copper will turn cherry-red). Do not point the flame directly at the solder!
Step 3. Soldering
Bring the solder to the place. connection. If the temperature is sufficient, it will begin to melt and flow into the gap. For reliability, move the tip of the torch along the seam so that the solder is evenly distributed. When soldering aluminum, use filler wire from the same alloy. filler wire from the same alloy.
Step 4. Cooling and checking
Allow the seam to cool naturally (do not cool with water!). Check the tightness with a soap solution: apply it to the seam and apply air to the tube under a pressure of 10-15 atmospheres. If there are no bubbles, soldering is successful.
⚠️ Attention: If you are soldering. handset in a charged system (without bleeding freon), the risk of explosion or poisoning is extremely high! Freon under pressure can ignite when heated. Work only on completely depressurized the system.
What to do if the solder does not stick?
If the solder rolls up into balls and does not wets the copper, the problem is one of three things:
1. Insufficient heating —heat the tube more strongly (should be cherry-red in color).
2. Poor stripping —repeat sanding and degreasing.
3. Wrong flux —for copper-phosphorus solder try F-38N, for silver - Harris Stay-Clean.
Common mistakes and how to avoid them
Even experienced craftsmen sometimes make mistakes that ruin all the work. Here are the most critical ones:
- 🔥 Overheating of the tube: if copper turns orange (over 900°C), it has lost strength. This area needs to be cut out and soldered again.
- 💧 Use of water for cooling: a sharp temperature difference leads to microcracks in the seam. The tube should cool in air.
- 🧴 Saving on flux: without flux, the solder will not flow into the gap, and the seam will be porous. For aluminum this is critical - the connection will fall apart in a few months.
- 🛠️ Soldering dirty pipes: residues of oil, grease or old freon interfere with adhesion. Degreasing with acetone is mandatory!
Another typical problem is insufficient tightness. If, after filling with freon, the refrigerator works for 1-2 days, and then stops freezing again, a microdefect in the seam is to blame. Check the tightness in two ways:
- With a soap solution under a pressure of 15 atmospheres.
- Electronic leak detector (for example, Inficon D-Tek Select).
Safety when soldering: protection from freon and burns
Soldering refrigerator tubes more dangerous than plumbing work due to the risk:
- 💨 Freon poisoning: even a small leak in a closed room causes dizziness and nausea. Work with open windows or with a hood.
- 🔥 Condenser explosion: if there is freon left in the system, it can always ignite when heated. bleed off the refrigerant before soldering!
- 🩹 Burns: copper conducts heat well - do not touch the tube with your bare hands even 10 minutes after soldering.
✅ Mandatory measures precautions:
- Use a respirator with an organic vapor filter (for example, 3M 6001).
- Wear Kevlar gloves - they protect against high temperatures and sparks.
- Keep at hand ABC class fire extinguisher (freon burns on contact with an open flame).
- Do not solder close flammable materials (plastic, wire insulation).
⚠️ Attention: If you are soldering refrigerator tubes with isobutane (R600a) as a refrigerant, remember: this gas is explosive at a concentration in air of more than 1.3%. Work only in a well-ventilated area or outdoors!
When soldering does not help: alternative repair methods
Soldering is effective for small cracks (up to 5 mm) or broken fittings, but in some cases it is useless or even useless. harmful:
- 🔧 Corrosion along the entire length of the tube: if copper is covered with a green coating (oxidation) on more than 30% of the surface, soldering will not restore the strength. The area needs to be replaced.
- 💥 Rupture along the weld seam: factory seams of the tubes (for example, in a condenser) are not repaired - only replacement of the part.
- ❄️ Cracks in evaporator: aluminum evaporators (No Frost-systems) are practically impossible to solder. Only argon welding helps here.
Alternative repair methods:
- 🔗 Crimp couplings (Swagelok): suitable for temporary repair of copper tubes with a diameter of up to 10 mm. Do not require heating, but are less reliable than soldering.
- 🔥 Argon welding: the only way to restore aluminum tubes. Requires special equipment.
- 🔄 Replacing a section of the tube: if the damage is large, it is easier to cut out the defective piece and solder a new section with fittings.
In industrial refrigerators (Lieberr, Carrier) are often used mechanical connections (for example, flange couplings), which do not require soldering. For household models this is rare - here soldering remains the most reliable method.
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 soldering iron (even at 100 W) is not enough to heat a copper tube to the melting temperature. CuP6 (700°C). The maximum you will achieve is a weak tin weld that will last for several days. For soldering you need gas burner (propane or acetylene).
What gas to use in the burner: propane. or acetylene?
For household refrigerators propane burner (flame temperature ~1300°C). Acetylene (temperature ~3000°C) is needed for soldering thick-walled pipes of industrial systems. However, acetylene is explosive - it is best to use it only in workshops with a hood.
How much does professional soldering of refrigerator tubes cost?
The cost depends on the complexity of the work:
- Soldering one crack: 1500–3000 rubles.
- Replacement section of a tube with fittings: 3500–6000 rubles.
- Soldering of an aluminum evaporator (argon): 5000–10000 rubles.
Prices are relevant for Moscow and the regions for 2026. The price usually includes leak diagnostics, soldering, evacuation and refilling. freon.
What happens if you solder the tube incorrectly?
The consequences depend on the type of error:
- Weak seam: freon leaks after 1-4 weeks, the compressor works without stopping and burns out.
- Overheating of the tube: copper becomes brittle, after 2-3 months a new crack appears.
- Using unsuitable solder (for example, tin): the seam is destroyed by vibration, freon mixes with oil and clogs the capillary tube.
In the worst case, a leaky seam leads to leakage of freon into the room this is dangerous to health (especially if the refrigerant R600a or R290).
Is it possible to solder refrigerator tubes without bleeding off freon?
Absolutely not! Freon under pressure when heated can:
- Explode (if there is any left in the system R600a or R290).
- Form toxic gases (for example, phosgene during decomposition R22).
- Enter the burner flame and ignite.
Before soldering required bleed freon through the service port and ventilate the room.