The situation when refrigerator stops freezing, but the compressor is still running almost without interruption, familiar to many owners of household appliances. In most cases, if there are no obvious refrigerant leaks or mechanical damage, the problem lies in a violation of the circulation of freon within the system. The main obstacle to the refrigerant path is a blockage, which is most often localized precisely in the narrow section of the capillary tube.
This thin copper element is a throttling device that ensures a sharp drop in the pressure and temperature of freon before entering the evaporator. Even a microscopic particle of oxide or a frozen paraffin plug can completely block the flow, turning the unit into an ordinary kitchen cabinet. Independent repair in this case, it requires not only accuracy, but also an understanding of the physical processes occurring inside the sealed circuit.
Before proceeding with active actions, it is necessary to clearly diagnose the problem so as not to do unnecessary work. It is important to understand that cleaning is only part of a comprehensive restoration, which often requires subsequent evacuation and refilling of the system. Ignoring these steps may lead to repeated failure of the equipment or damage to more expensive components.
⚠️ Attention: Any manipulations with the sealed circuit of the refrigerator require special tools and skills. Violation of the integrity of the tubes without subsequent evacuation will lead to the ingress of moisture and air, which is guaranteed to damage the compressor.
Diagnostics of a blockage: symptoms and signs
The presence of a plug in capillary system can be determined by the characteristic signs that appear during the operating mode of the unit. The first and most obvious signal is the continuous operation of the motor-compressor. The unit hums, trying to create the necessary pressure, but cannot push freon through the clogged area.
In this case, the temperature regime inside the chambers is disrupted: in the freezer compartment it may be a little cooler than in the room, but ice does not form. If you touch the condenser (grid at the back), it will be cold or slightly warm, instead of being hot over the entire area.
To accurately determine the location of the blockage, technicians often use the palpation method or a thermal imager. In the place where the tube suddenly changes temperature from hot to cold, there is most likely an obstruction. It is also worth paying attention to:
- 🧊 Complete absence of frost on the evaporator when the compressor is running.
- 🔊 Change in the sound of the engine (it can work more strained).
- 🌡️ Temperature difference between the discharge and suction tubes compressor.
It is important to distinguish a blockage from a leak or compressor failure. If there is a leak, there is simply no pressure in the system, and if the motor breaks down, there is no characteristic sound of operation and vibration. If the engine is humming, but there is no cold, this is almost certainly a circulation problem.
Necessary tools and preparation of the workplace
To perform high-quality work on removing blockages you will need a specialized set of tools, which is not always in the arsenal of a home craftsman. The basic element is a nitrogen cylinder, since it is the inert gas that is used to purify and create pressure in the circuit.
In addition, you will need a torch (gas or oxy-acetylene) for soldering copper connections. The use of tin or soft solders is unacceptable here, since the system operates under high pressure and requires copper-copper or copper-steel hard soldering.
Be sure to prepare the following components:
- 🛠️ Vacuum pump to remove moisture and air from the system.
- ⚗️ Manometric manifold for monitoring pressure during refueling.
- 🧹 Filter-drier (mandatory replacement when opening the circuit).
- 🔩 A new piece of copper tube for insertion into the capillary.
Workplace should be well lit and ventilated. When working with open flames and chemicals (freon, solder), compliance with safety precautions is a critical factor. Remove flammable items away from the repair area.
☑️ Readiness for repair
Nitrogen purging technology: the main method
The most effective and common way is to make a capillary tube is nitrogen purging under high pressure. This method allows you to mechanically knock out a plug of oxides or paraffin without damaging the internal walls of a thin tube.
The process begins by disconnecting the refrigerator from the network and accessing the process pipe of the compressor. The technician cuts off the sealed end, installs the fitting and connects the nitrogen cylinder. Pressure is applied in pulses to create a hydraulic shock that can dislodge the blockage.
It is important to control the pressure so as not to rupture the thin-walled elements of the evaporator. Typically the process looks like this:
Purge pressure: 10-15 atm (pulse)Holding time: 3-5 seconds per pulse
Number of cycles: up to 10 times
If the blockage is deep, it may be necessary unsolder the capillary tube from the filter drier and blow the system in the opposite direction. This allows debris to be pushed towards the compressor, where it often gets stuck in a blind area or comes out through an open pipe.
⚠️ Attention: Never use oxygen or compressed air from the compressor for purging. Oxygen in combination with compressor oil can cause an explosion, and the air contains moisture, which will turn into ice inside the system.
Why nitrogen?
Nitrogen is an inert gas, which eliminates chemical reactions with oil and metals at high soldering temperatures. In addition, technical nitrogen does not contain moisture, which is critical for refrigeration systems where water causes corrosion and blockage of the capillary with ice.
Mechanical cleaning and chemical methods
In cases where gas purging does not produce results, the mechanical method is used. It is more risky, since there is a possibility of damaging the thin wall of the tube with a diameter of less than 1 mm. For this, a special steel string is used, which is carefully inserted into the tube.
Movements must be progressive and very careful. Do not make any forceful rotational movements to avoid scratching the inner surface of the copper. Scratches will become centers of corrosion in the future, which will again lead to blockages.
Sometimes the cause is not solid debris, but congealed oil or paraffin. In such cases, heating a section of the tube with a hair dryer or torch helps (very carefully!). Softened paraffin is easier to blow out with nitrogen.
There is a table corresponding to the type of blockage:
| Type of blockage | Symptom | Cleaning method | Efficiency |
|---|---|---|---|
| Paraffin plug | Appears only at low temperatures | Heating and purging | High |
| Oxides copper | Permanent blockage, black deposits | Mechanical cleaning | Average |
| Moisture (ice) | Cyclic operation (freezes-not freezes) | Vacuuming | High |
| Oil breakdown products | Sour smell, dirt | Rinsing and changing oil | Low |
It is better not to use chemical solvents at home, as they are difficult to completely remove from the system. Residues of chemicals can react with the refrigerant or oil, forming aggressive acids.
Replacement of the filter drier and evacuation
Any opening of the circuit, even short-term, requires mandatory replacing the filter-drier. This element is responsible for absorbing moisture that inevitably enters the system from the air. The old filter is already saturated and will not be able to perform its function.
The filter is installed immediately after the condenser, before entering the capillary tube. When soldering a new filter, you must work quickly to minimize the time the internal elements are in contact with atmospheric air. The filter should not be overheated - this may activate the filler ahead of time.
After soldering all connections, the vacuum stage begins. This is a critical process that takes at least 30-40 minutes. The vacuum pump removes air and, more importantly, evaporates and removes moisture from the system at low pressure.
Only after achieving a deep vacuum (about -1 atm or 760 mm Hg) and checking the system for leaks for 15-20 minutes, you can start filling with refrigerant. Skipping the evacuation stage is guaranteed to lead to the formation of an ice plug in the capillary in a short time.
Refrigerant charging and final check
The final stage of repair is charging the system freon. The amount of refrigerant is strictly regulated by the manufacturer and is indicated on a sticker inside the refrigerator or in the technical documentation. Using the wrong type of gas or incorrect dosage is unacceptable.
Refilling is done in the liquid phase (cylinder down) with the compressor turned off in order to gain the bulk, and then, with the engine on, the remainder is taken in the gaseous phase through the suction pipe. The pressure in the system depends on the ambient temperature and the type of refrigerant.
Control of correct filling is carried out by:
- ❄️ Uniform cooling of the evaporator.
- 🌡️ Temperature of the suction tube (it should be slightly warm or room temperature, but not hot and not covered with frost at the compressor itself).
- ⏱️ Cyclical operation (work and rest times must correspond to the norm).
⚠️ Attention: The type of refrigerant (R134a, R600a, R12) is critical. The use of R134a in a system designed for R600a (isobutane) can lead to an explosive situation or destruction of the compressor seals.
After refueling, the soldering joints must be checked with a soapy solution for leaks. Bubbles will indicate a defect in the work. If the system is sealed, the process pipe is sealed and the refrigerator is left to set the temperature.
Is it possible to clean the capillary without a nitrogen cylinder?
Theoretically, you can try using a compressor from an old refrigerator, but it will not provide the required pressure (usually up to 4-6 atm, but 10-15 is needed). In addition, such a compressor will pump air with moisture and oil, which will finally finish off the system. Without nitrogen, high-quality cleaning is impossible.
Why did the refrigerator stop freezing again after a month after cleaning?
Most likely, a mistake was made during the repair: the filter drier was not replaced, the system was poorly evacuated, or the wrong solder was used. The moisture remaining in the system froze in the capillary, forming a new ice plug.
Is it dangerous to open the refrigerator circuit yourself?
Yes, it is dangerous. Firstly, there is a risk of burns when soldering. Secondly, some refrigerants, when in contact with an open burner flame, form phosgene, a chemical warfare agent. Thirdly, isobutane (R600a), used in many modern models, is explosive when concentrated in air.
How much does it cost to professionally clean the capillary?
The price depends on the region and model of the refrigerator, but usually consists of the cost of work (blowing, soldering, vacuum) and the cost of materials (freon, filter, solder). On average, this constitutes a significant part of the cost of a new budget refrigerator.