Modern refrigerator is a complex system where each element is responsible for maintaining a stable temperature. Often, equipment owners are faced with a situation where the unit stops freezing, and diagnostics reveal a problem in the refrigerant circulation system. One of the hidden but critical details that ensure the tightness of this system is lockring. This is a connection that often becomes the cause of freon leakage during poor-quality factory installation or after unprofessional maintenance.
Understanding what it is locking and how it functions is necessary not only for craftsmen, but also for those who want to understand the structure of their household appliance. Unlike traditional soldered joints, this element has a specific design that allows you to connect copper tubes of different diameters without the use of solder. However, it is precisely this feature that makes it a vulnerable point that requires special attention when refrigerator repair.
In this article we will analyze in detail the design of this unit, the reasons for its failure and troubleshooting methods. You will find out why Steel lockrings are susceptible to corrosion faster than copper counterpartsand whether it is worth changing them to a solder joint. The information will help you make an informed decision about the advisability of independent intervention or calling a specialist.
Design features of a locking connection
Lockring (from English "locking ring") - this is a crimp connecting ring used for a hermetically sealed joint between copper tubes in the cooling circuits. The design is simple and ingenious: it consists of two main parts. The first part is the adapter itself, which is inserted inside a larger diameter tube. The second part is the outer ring, which is placed on top of the joint and crimped with a special tool.
The principle of operation is based on mechanical deformation. When crimping, the outer ring compresses the wall of the outer tube, pressing it tightly against the inner adapter. This creates enough pressure to keep freon under high pressure. Unlike soldering, open flame is not used here, which theoretically reduces the risk of damage to the insulation or plastic elements inside the refrigerator cabinet during factory assembly.
However, this design has its own characteristics. Tightness is ensured solely by the force of friction and the tightness of the metals. If the geometry of the tubes is incorrect or the crimping tool is incorrectly selected, microscopic gaps can lead to leakage. That is why lockring connections is often considered as a less reliable alternative to classic brazing in the long term.
Main causes of failure and leaks
Despite the apparent reliability, statistics from service centers show that a significant part of leaks in new refrigerators occur in these places locking connections. The main reason is a manufacturing defect or a violation of the crimping technology on the conveyor. Even a minimal displacement of the tubes relative to each other at the time of crimping creates a channel for the gradual release of the refrigerant.
The second important reason is corrosion. Moisture entering the condensation zone or formed during defrosting reacts with the ring material. If steel is used without proper anti-corrosion coating, rust will quickly eat away at the metal. This is especially true for refrigerators installed in rooms with high humidity or in kitchens with poor ventilation.
Vibration also cannot be ignored. During operation, the compressor creates vibrations that are transmitted to the entire pipeline. Over time, the metal in the stress zone gets tired, and microcracks may appear in the ring itself or in the adjacent area of the tube. This leads to a situation where the refrigerator stops freezing, although visually the compressor is working properly.
The hidden danger of vibration
Vibration is dangerous not only for lockers, but also for the capillary tube. If the refrigerator is not level, the amplitude of vibrations increases, which can lead to the tube coming off the filter-drier or the locking itself after several years of operation.
There is also a human factor. If you tried to repair or move the refrigerator yourself without following the transportation rules, the tubes could be bent. The stress in the metal at the bending point per zone connectionssooner or later will lead to depressurization.
Fault diagnosis: how to find a leak
Determine that the problem lies precisely in locking, without special equipment it is almost impossible. The first sign for the owner is a decrease in cooling efficiency or a complete absence of cold when the engine is running. However, these symptoms may also indicate other malfunctions, so professional diagnostics are necessary.
Masters use several methods for finding leaks. The most common is to use a leak detector or soap solution. When nitrogen is supplied to the system, the gas outlet begins to “hiss” or become covered with bubbles. Locking valves are usually located at the lower rear of the refrigerator, near the compressor, or hidden in a foamed part of the cabinet, making access difficult.
If the leak is found in an accessible location, repairs are quick. But if connection is located in a foamed area (for example, in an evaporator walled into a wall), the situation becomes more complicated. In this case, you often have to open the thermal insulation or, more reliably, resolder the circuit, bringing new tubes out.
Replacing the locking: step-by-step instructions
Replacement process locking connection requires special tools and skills in working with refrigeration equipment. This is not an operation that can be done with pliers or a hammer. An unprofessional approach is guaranteed to lead to repeated leakage or damage to the pipes.
First, you need to completely bleed the refrigerant from the system. This is done through a Schrader valve or by piercing the process tube. After evacuating the system and removing the old connection, it is necessary to prepare new copper tubes. They should be perfectly smooth and clean inside.
The next step is installing a new adapter and ferrule. Here it is critical to use locking pliers (crimping pliers) of the appropriate diameter. The tool must create uniform pressure around the entire circumference.
☑️ Tools for replacing lockring
After the mechanical connection, it is necessary to carry out pressure testing with nitrogen. This is a leak test under pressure exceeding operating pressure. If the pressure gauge holds pressure for 24 hours, you can proceed to evacuation and filling freon. Ignoring the evacuation step will cause the remaining moisture in the system to freeze in the capillary pipe and block circulation.
⚠️ Attention: It is strictly forbidden to use an open flame in the immediate vicinity of the locking joint unless you have the skills to quickly solder with a heat sink. Overheating of the ring can release the metal, and the connection will lose its tightness immediately after cooling.
Is it worth changing the lockring for soldering?
Many repair technicians suggest not installing a new one lockring, and replace this unit with a solder connection. This is a controversial point that has its pros and cons. On the one hand, high-quality soldering copper-copper or copper-steel (using special solders) is considered more durable and reliable.
On the other hand, soldering a steel tube (which is often paired with copper in factory lockrings) requires high temperatures and special fluxes. Incompetent soldering can burn through the thin wall of the tube or leave oxides inside, which will subsequently clog capillary tube. Lockring in this sense is simpler: it does not require heating and is chemically inert.
However, if the repair is carried out by a qualified specialist using silver solder and proper fluxing, switching to soldering prolongs the life of the refrigerator. Statistics show that circuits converted to soldering last longer than restored lockrings, especially in aggressive environments.
It is also important to consider the material tubes If you Atlant refrigerator or Indesit, steel tubes are often found there. Soldering steel is difficult, so in such cases, installing high-quality copper locking may be even preferable to low-quality soldering.
Comparison of connection characteristics
To better understand the difference between a factory connection and alternative repair methods, let's consider their main parameters. The table below will help you navigate the advantages and disadvantages of each approach.
| Parameter | Locking connection | Brass soldering | Threaded connection |
|---|---|---|---|
| Reliability | Average (depending on the quality of crimping) | High (subject to technology) | Low (risk of vibration leaks) |
| Complexity installation | Low (special tools required) | High (skill and burner required) | Medium |
| Risk for insulation | Absent (no heating) | High (risk of melting) | Absent |
| Durability | 5-10 years | 10-15 years or more | 3-5 years |
As can be seen from the table, soldering wins in terms of durability, but requires skill. Lockring is a compromise chosen by manufacturers to speed up assembly on the assembly line. It is important for the end user to understand that when repairing “as in the factory” (that is, installing a new locking), you are returning the equipment to its original condition with all its potential risks.
⚠️ Attention: Never use threaded fittings (“American”) to permanently connect pipes inside the refrigerator circuit. They are intended only for temporary connection of pressure gauges and are a common cause of leaks due to vibration.
Prevention and operating recommendations
To extend the life of the refrigerant circulation system, it is important to follow the operating rules. Avoid mechanical impacts on the rear grille of the refrigerator. Even a slight blow can disrupt the geometry of the tubes in place locking connection and provoke a microcrack.
Regularly check the back wall for corrosion. If you notice rust around the compressor, this is a red flag. Moisture should not stagnate in the tray or on the floor under the equipment. Ensure good ventilation of the installation area so that the condensation quickly evaporates.
When moving or transporting the refrigerator, be sure to secure the compressor with transport bolts (if they are provided by the design) or carefully pack the unit to prevent loose internal components. Sharp jerks can be fatal for old, “tired” connections.
Frequently asked questions (FAQ)
Is it possible to seal the locking with sealant in the event of a leak?
No, conventional sealants cannot withstand the pressure and temperature in the system, as well as the chemical effects of freon and oil. This “patch” is temporary and dangerous. A complete re-welding or re-crimping of the connection is required.
How much does it cost to replace the locking in the service?
The price consists of the cost of work (vacuuming, refueling, replacement itself) and materials. On average, this can range from 30% to 50% of the cost of a new budget refrigerator, since the work is labor-intensive.
Why are lockrings installed at the factory if they leak?
This is a way to reduce the cost and speed up assembly. Automatic crimping of lockring takes seconds and does not require a qualified welder, unlike manual soldering, which is critical for mass production.
Is it possible to use lockring to connect tubes of different diameters?
Yes, that is exactly what they are designed for. The internal insert (adapter) has a stepped design that allows you to join tubes with different wall thicknesses or diameters, which is often found in refrigeration technology.