The appearance of a puddle under the refrigerator or a characteristic whistle of escaping gas often indicates depressurization of the circuit, and in most cases the source of the problem becomes evaporator. This is the heart of the cooling system, which is constantly exposed to temperature changes and mechanical stress, which over time leads to the formation of microcracks. Many owners of household appliances are wondering whether it is possible to restore the integrity of the tubes themselves, without resorting to an expensive call to a technician.
Repairing an evaporator is not just a mechanical connection of metals, but a complex technological process that requires an understanding of the physics of freon and the properties of solder. Aluminium and copper alloys used in modern models behave differently when heated, and an error in choosing the temperature can completely ruin the part. In this article, we will analyze in detail how to solder a refrigerator evaporator, what tools are needed and why the system will not work without vacuuming.
Before you take on the burner, you need to clearly understand the risks: working with open fire and gas under pressure requires extreme concentration. Improper soldering can lead not only to repeated leakage, but also to compressor failure or even fire. If you are not confident in your abilities or you do not have specialized equipment, it is better to stop at the diagnostic stage.
Diagnostics of damage and search for leaks
The first stage of restoration is to accurately determine the location of the depressurization. Often a visual inspection does not yield results, since cracks may be microscopic or hidden under a layer of thermal insulation. To search for leaks, technicians use leak detectorwhich reacts to refrigerant vapors, or the old proven method with a soap solution.
If the refrigerator still contains remnants of freon, the search process is simplified: just apply soap foam to suspicious areas and observe the appearance of bubbles. In the case where the circuit is already empty, you will have to first introduce nitrogen into the system at a slight pressure to create excess pressure for the test. Be careful: the pressure should not exceed the permissible limits for a particular type of evaporator.
⚠️ Attention: Never use oxygen to create pressure in the refrigerator circuit! A mixture of oxygen and oil residues in the compressor can lead to a powerful explosion when struck by a spark.
Particular attention should be paid to the places where factory connections are soldered and the areas where the tubes come into contact with the metal casing. This is where it most often occurs Electrochemical corrosion, which thins the wall of the tube to the state of foil. Also check the inlet and outlet of the foamed part, where mechanical stress often occurs.
Preparation of tools and selection of materials
The quality of soldering directly depends on the correct choice of consumables and tools. To work, you will need a gas burner with a narrow flame to locally heat the joint without melting adjacent elements. The melting point of the solder must be selected so that it flows but does not burn the base metal.
The choice of flux and solder is a critically important point, especially if you are working with aluminum evaporators that oxidize instantly in air. Regular tin-lead solder will not work here - you need a special composition with high adhesion to aluminum or the use of argon-arc welding for serious damage.
- 🔥 Gas torch with a cylinder (propane-butane or MAPP gas for higher temperatures).
- 🛠️ A set of needle files and sandpaper for cleaning oxides.
- 🧪 Flux for soldering aluminum or copper (depending on the tube material).
- 🔩 Rolling tool and pipe cutter, if a section needs to be replaced.
Don't forget to prepare personal protective equipment: fireproof gloves, goggles and a respirator. When old pipes heat up and factory paint burns, toxic substances can be released. You should also have a fire extinguisher on hand, since the work is carried out in close proximity to the plastic elements of the refrigerator.
Technology for soldering copper and aluminum tubes
The soldering process varies dramatically depending on the metal. Copper is relatively easy to solder: just clean the surface to a shine, heat the joint and introduce solder. The molten metal itself will flow into the gap due to the capillary effect, creating a sealed seam.
C aluminum the situation is more complicated. This metal is covered with a refractory oxide film, which must be destroyed mechanically or chemically immediately before soldering. The method of rubbing solder with a heated rod or the use of active fluxes that dissolve oxides at high temperatures is often used.
The work technique requires smooth movements. The burner flame should be directed not at the solder itself, but at the metal next to the seam in order to heat it to the desired temperature. If you only heat the solder, it will roll into a ball and will not stick to the tube.
The secret of soldering aluminum
To successfully solder aluminum without argon, try heating the soldering area to the melting temperature of the solder, then vigorously rub the contact area with a hard solder rod, removing the oxide film. This requires skill and speed.
After soldering is completed, it is necessary to allow the seam to cool naturally. Rapid cooling with water can lead to the appearance of microcracks in the heat-affected zone, especially in thin-walled evaporator tubes. Check the seam visually: it should be smooth, without cavities or sagging.
Replacing the evaporator section and rolling
In cases where corrosion has eaten up a significant section of the tube, simple soldering may not help. Then a decision is made to insert a repair insert from a copper tube of suitable diameter. This is a more reliable method that allows you to cut out the damaged segment completely.
To connect the insert, copper taps or straight sections are used that are rolled at the ends. Rolling allows you to create a cone-shaped extension that tightly covers the inserted tube, ensuring mechanical strength and tightness of the connection before soldering.
| Type of connection | Tube material | Required tool | Complexity |
|---|---|---|---|
| Butt with outlet | Copper-Copper | Pipe cutter, rolling | Medium |
| Lapped | Aluminium-Aluminium | Needle file, burner | High |
| Repair coupling | Steel-Copper | Soldering iron (for steel) | Low |
| Argon welding | Any alloy | Welding machine | Pro |
When inserting a new section, it is important to observe the direction of movement of the refrigerant, although for a capillary system this is less critical than for industrial ones installations. The main thing is to ensure minimal hydraulic resistance and the absence of narrowing at the joint.
Evacuation of the system: a mandatory stage
After soldering is completed and the tightness is checked with nitrogen, the most important stage begins - vacuuming. There should be no air and, most importantly, moisture left in the system. Water that gets into the circuit freezes in the capillary tube, forming an ice plug that blocks the circulation of freon.
To remove moisture and air, a vacuum pump connected to the service pipe is used. The process should last at least 30-40 minutes, and ideally up to an hour, so that all moisture evaporates even from hard-to-reach places. The pressure in the system should drop to a deep vacuum.
⚠️ Attention: If after evacuation the system maintains a vacuum, but when the compressor starts, the pressure rises sharply, it means that there is a hidden leak somewhere or moisture continues to evaporate from the compressor oil.
Vacuum control is carried out by a pressure gauge station. The pressure gauge needle should confidently move into the blue zone (negative values). After turning off the pump, you need to turn off the valve and watch the pressure gauge for another 15-20 minutes: if the arrow creeps up, the seal is broken.
☑️ Checklist before vacuuming
Filling the refrigerator with refrigerant
Final The key to repair is refueling the system refrigerant. The type of freon (R134a, R600a, R12) must strictly correspond to the marking on the compressor or the refrigerator’s passport data. Using the wrong gas will lead to incorrect operation or breakdown of the compressor.
Refilling is carried out with the compressor running through the service pipe. The amount of refrigerant is determined by scales (grams) or by the suction pressure and current consumption of the compressor. For household refrigerators with freon R600a (isobutane), the weight dosage is critically important due to the explosiveness of the gas.
After refueling, it is necessary to seal the filling pipe by pinching it with pliers and soldering the tip. This guarantees complete tightness of the circuit for many years. Then the refrigerator is turned on and the uniform cooling of the evaporator and the operation of the thermostat are checked.
Common mistakes and safety measures
The most common mistake during repairs is neglecting to clean the surface before soldering. Oxides and dirt will prevent the solder from spreading, and the seam will be porous. Also, beginners often overheat the soldering area, burning through the thin wall of the evaporator, especially if it is made of aluminum.
Another critical mistake is charging the system without a deep vacuum. After a couple of months of operation, the remaining moisture will turn into acid, which will corrode the compressor windings from the inside, and repairs will become economically unfeasible. Always use a quality vacuum pump.
- 🚫 Do not solder under pressure - this is a guaranteed explosion or fire.
- 🚫 Do not use an open flame in a room without ventilation, especially with R600a freon.
- 🚫 Do not leave the system open to the air for more than 15 minutes to avoid moisture ingress.
Remember that modern refrigerators often have foamed evaporators, access to which requires disassembling the case or carefully opening the foamed layer. In such cases, repairing the evaporator is often replaced by installing an external “crying” evaporator inside the chamber, which is simpler and more reliable for a home craftsman.
Is it possible to solder the evaporator with ordinary tin solder?
The usual POS-60 or POS-40 is only suitable for copper. For aluminum, from which most modern evaporators are made, it is not suitable due to the oxide film. Special fluxes or solders containing zinc and silicon are required, or welding.
How much does it cost to repair an evaporator compared to a new one?
The cost of materials for soldering and refilling (flux, solder, freon, nitrogen) is usually 10-15% of the price of a new refrigerator. However, if the compressor needs to be replaced due to moisture, the cost of repairs can reach 50%.
Why does the refrigerator not freeze after soldering?
Most likely, an ice plug has formed in the capillary tube due to moisture or the filter drier is clogged. Also, the cause may be poor-quality soldering that blocked the passage hole, or freon leakage through a leaky seam.