The sudden appearance of a puddle under the refrigerator or the complete cessation of operation of the unit often indicates a violation of the tightness of the system. Refrigerator tubes are the blood vessels of this complex mechanism, and their damage results in refrigerant leakage. Owners of household appliances often panic, thinking that the device has completely failed, but in many cases the situation can be corrected.
Independent refrigerator tube repair requires not only theoretical knowledge, but also the presence of special equipment. Without a vacuum pump, burner and pressure gauge station, it is impossible to perform high-quality refueling. However, understanding the processes occurring inside the circuit will help you diagnose the problem and make an informed decision about calling a technician or doing the repair yourself.
In this article we will examine in detail the design of the refrigeration circuit, methods for finding leaks and the technology of soldering copper connections. You will learn why Mechanical damage to the tube often occurs due to inaccurate defrosting with a sharp objectand how to properly prepare the system for restart. Compliance with safety precautions when working with flammable gases and open fire is a must.
Diagnostics and search for the location of a refrigerant leak
The first step in the restoration process is to accurately determine the location where the leak occurred depressurization of the system. If you hear hissing or see oily spots on the inner walls of the chamber, these are sure signs that it has already begun. Visual inspection often reveals obvious mechanical damage, especially in the evaporator area or on the rear condenser grille. freon leak has already begun. Visual inspection will often reveal obvious mechanical damage, especially in the evaporator area or on the condenser rear grille.
However, microscopic cracks are not always visible to the naked eye. To detect them, professionals use a soap solution, which is applied to suspicious areas while the compressor is on. The appearance of bubbles will indicate the exact location of the release of gas under pressure. If the leak is in the foamed part of the housing, diagnosis becomes much more complicated and may require opening the thermal insulation.
There are several main reasons why the integrity of the pipeline is compromised:
- 🔨 Mechanical damage with a sharp object when trying to pry off frozen ice or food.
- 🔥 Metal corrosion, caused by long-term operation in conditions of high humidity.
- 🏭 Factory defective soldering, which appears after several years of active operation of the device.
- 🐀 The activity of rodents gnawing through soft aluminum or copper tubes in the lower part of the unit.
It is important to understand that even a small hole a fraction of a millimeter in diameter will result in complete loss of refrigerant within a few hours or days. After discovering a defect, you must immediately stop using the device and disconnect it from the power supply. Continued operation of the compressor without cooling with oil and freon can lead to its costly failure.
Necessary tools and materials for soldering
High-quality repairs are impossible without the appropriate technical equipment. The basic element of the set is a gas burner operating on a propane-butane mixture or MAP gas. For copper tubing up to 20 mm in diameter, a portable torch is sufficient, but for steel or aluminum elements, more powerful equipment with oxygen blast may be required.
The second critical component is solder. To connect copper pipes in refrigeration systems, silver or phosphorus-containing rods are most often used, which provide high strength to the seam. Tin-lead solders (POS) have too low a melting point and are not recommended for highly loaded areas of the system, where vibration of the compressor can destroy the connection.
To prepare pipes for soldering, you will need:
- 🔪 A pipe cutter to obtain an even cut without burrs.
- 🧹 A brush-brush for cleaning the internal and external surfaces of the metal.
- 🔧 Rolling to expand the ends of pipes in the absence of finished ones fittings.
- 🔥 Flux (borax or special paste) to prevent metal oxidation when heated.
Do not forget about personal protective equipment. Working with open flames and chemicals requires safety glasses and heat-resistant gloves. The room where the work is carried out must be well ventilated, since when the flux and oil residues are heated, toxic substances can be released.
Technology for soldering copper and aluminum tubes
The process of connecting metal elements of the refrigeration circuit requires strict adherence to the temperature regime. Before soldering, the surfaces of the pipes must be thoroughly cleaned to a metallic shine, removing the oxide film. A thin layer of flux is applied to the cleaned areas, which facilitates the spreading of solder and protects the metal from oxidation during heating.
The pipe should be heated evenly, moving the burner flame along the entire circumference of the joint. You cannot direct the fire directly to the solder - it must melt from the heat of the hot metal of the pipe. When the temperature reaches the desired value, the solder will begin to actively flow into the gap between the pipes under the action of the capillary effect, forming a monolithic connection.
There are differences in approaches to soldering different metals:
- 🔸 Copper-copper: it is easy to solder, often without additional flux, if phosphorus solder is used.
- 🔸 Copper-steel: requires the mandatory use of flux and silver solder with a silver content of at least 30%.
- 🔸 Aluminum: extremely difficult to solder due to rapid oxidation, requires special fluxes and temperature control.
⚠️ Attention: When soldering tubes that were previously part of the working system, oil may remain inside. When heated, it may burst into flames, so warm up the joint carefully and keep a fire extinguisher or a wet rag at hand.
After soldering is completed, the joint must be allowed to cool naturally. It is not recommended to cool the seam with water or compressed air, as a sudden temperature change can cause microcracks in the metal structure. The cooled seam should be wiped with a damp rag to remove flux residues, which can cause corrosion over time.
Why can’t you use regular tin solder?
Ordinary POS-61 has a low melting point (about 190°C) and low mechanical strength. In a refrigerator system, where the pressure can reach 15-20 atmospheres, and the compressor creates constant vibration, such a seam will quickly collapse. In addition, tin can react with some types of refrigerants and oil, forming acids that will clog the capillary tube.
Replacing the damaged section and inserting a new tube
If the damage is localized on a straight section of the line, the easiest way is to cut out the defective piece and insert a new insert. To do this, two perpendicular cuts are made with a pipe cutter to remove the damaged area. The new tube must be the same diameter and material as the original to ensure unhindered circulation of the refrigerant.
When installing a new section, it is important to maintain minimum soldering clearances. The insert pipe must fit into the main line with a slight interference fit or a minimum gap (no more than 0.1 mm). If the gap is too large, the capillary effect will not work and the solder will not fill the joint evenly, which will lead to leaks.
Parameters for replacing pipeline sections:
| Pipe type | Diameter (inch) | Insert material | Solder type |
|---|---|---|---|
| Injection | 1/4" - 3/8" | Copper | Silver (30%+) |
| Suction | 3/8" - 5/8" | Copper | Phosphorous |
| Capillary | 0.03" - 0.05" | Copper | Silver (high fluidity) |
| Capacitor | 1/4" - 3/8" | Steel/Aluminium | Special flux + solder |
In cases where the capillary tube is damaged, the situation becomes more complicated. This is an element with a very thin internal diameter, responsible for throttling the refrigerant. Replacing the capillary tube requires strict adherence to its length and internal diameter specified by the manufacturer. Even a minimal deviation in size will lead to improper operation of the refrigerator: either it will not freeze, or it will work with overload.
After inserting a new section, it is necessary to carry out pressure testing with nitrogen. This will allow you to check the tightness of all new seams under pressure exceeding working pressure. Only after making sure that there is no pressure drop on the pressure gauge within 12-24 hours can you proceed to the next stage - evacuation.
Evacuation of the system and charging with refrigerant
The most critical stage of repair is the removal of air and moisture from the system. When the moisture remaining inside the capillary tube freezes, it forms an ice plug, blocking the circulation of freon. The air containing nitrogen and oxygen increases the condensation pressure and promotes the oxidation of the oil, turning it into acid. corrodes the compressor winding from the inside.
To remove gases, a vacuum pump is used, connected to the service connection. The evacuation process should last at least 30-40 minutes for domestic refrigerators. The residual pressure in the system should be no more than 50-100 microns (0.05-0.1 mm Hg. After turning off the pump, it is necessary to close the valves and stand). pause for control: if the pressure increases, it means that there is a leak somewhere or moisture is evaporating from hard-to-reach places.
Refilling the refrigerator is carried out strictly according to the weight indicated on the nameplate (usually located on the back wall or inside the chamber) Using cylinders without scales is unacceptable, since it is impossible to determine the amount of refrigerant “by eye.” Underfilling will lead to insufficient cold. refilling leads to liquid hydraulic shock in the compressor, which is fatal for the mechanism.
⚠️ Attention: The type of refrigerant must strictly comply with the marking. Replacing R134a with R600a (isobutane) without completely reworking the system and changing the oil is prohibited, since isobutane is explosive and requires other oils.
During the filling process, the compressor must be turned on. Freon is supplied in the liquid phase (the cylinder is turned over) in small portions so that the compressor has time to pump gas into the condenser. After filling the required amount of refrigerant, the service pipe is sealed. Operation control is made according to the temperature of the condenser. (it should be warm evenly) and the temperature of the evaporator (it should be evenly overgrown with frost).
☑️ Checklist before starting
Typical mistakes during self-repair
Attempts to save money on equipment or neglect of technological processes often lead to repeated breakdowns. One of the most common mistakes is soldering without nitrogen purge. When copper is heated, oxide sludge is formed inside the pipe, which over time clogs the filter-drier and capillary tube, causing clogging. systems.
Another common mistake is the use of inappropriate materials. Attempts to seal the hole with epoxy resin or “cold welding” give only a temporary effect. Under the influence of temperature changes and vibration, such patches fall off, often after the system has been charged, which leads to repeated leakage and loss of expensive freon.
The main reasons for unsuccessful repairs:
- ❌ Lack of vacuum, which leads to the formation of ice plugs.
- ❌ Overheating of the pipe during soldering, leading to burnout of the metal and the formation of new holes near the seam.
- ❌ Using an old one filter-drier, which has already lost its properties and cannot absorb moisture.
- ❌ Ignoring the replacement of oil in the compressor during prolonged contact of the system with atmospheric air.
It is also worth mentioning the mistake of saving on the filter-drier. This element is disposable for any opening of the circuit (and soldering the tube is. opening) the filter must be replaced with a new one. The old adsorbent is already saturated with moisture and will not be able to protect the system from contamination, which will ultimately damage the compressor.
Frequently asked questions (FAQ)
Is it possible to solder a refrigerator tube with ordinary tin?
Technically, it is possible to solder it, but such a refrigerator will not work for long. Tin (POS) has a low melting point and does not tolerate vibration. Microcracks often form in places where tin is soldered. freon evaporates. For reliable repairs, use silver or copper-phosphorus solders.
How much does it cost to refill a refrigerator after repairing the tube?
The cost consists of the work of the technician, the cost of freon, filter-drier and evacuation. On average, the price may vary depending on the region and the type of refrigerant. check with specialists, since it depends on the difficulty of access to the soldering point.
How to understand that there is moisture left in the system?
The main sign of moisture is the cyclic operation of the refrigerator: it freezes, then stops (the capillary freezes), thaws and starts to freeze again. Frost may also appear on the filter drier. This can only be treated. repeated evacuation and replacement of the filter.
Is it necessary to change the oil in the compressor when soldering the tube?
If the system was depressurized for a short time (several hours) and the compressor did not run idle for a long time, the oil may not be changed, but the filter drier must be replaced. If the compressor has been running air for a long time or the system has been open. day, it is better to replace the oil, as it could have collected moisture.