Sudden cessation of operation of the refrigeration chamber or the appearance of ice at the entrance to the evaporator often indicates a serious malfunction in the refrigerant circuit. Capillary tube is the narrowest section of the freon pipe, and it is here that ice or mud plugs most often form, blocking refrigerant circulation. Without proper freon pressure and current, heat exchange in the evaporator becomes impossible, which leads to spoilage of products and failure of the compressor.
Restoring the permeability of the system requires not only special tools, but also a deep understanding of the thermodynamic processes occurring inside the unit. Safety precautions when working with high pressure and chemically active substances must be strictly observed, since an error can lead to an explosion of the cylinder or damage to the refrigerator components. In this article, we will look at diagnosing a blockage, methods for eliminating it, and the nuances of replacing related elements.
Independent cleaning is possible only if you have experience working with refrigeration equipment and the appropriate set of tools. If you are not confident in your abilities, it is better to contact a service center, but detailed instructions are provided below for amateur and professional craftsmen. It is important to understand that the cause of the blockage most often lies in the oxidation of copper tubes from the inside or moisture entering the circuitwhich requires an integrated approach to repair.
Diagnostics: how to determine a blockage of the capillary tube
The first sign The malfunction is the unnatural behavior of the compressor: it can work continuously without turning off, or start for a short time with a characteristic click and hum. At the same time evaporator in the freezer it either does not cool at all or is covered with frost only in the initial part, while the rest of the surface remains warm. This is a classic symptom that the refrigerant is not entering the system in the required volume.
For an accurate diagnosis, it is necessary to listen to the operation of the unit and conduct a visual inspection. Often, at the point where the capillary tube exits the housing or in the zone filter-drier one can notice abundant formation of frost or, conversely, the absence of condensate where it should be. If you can hear gurgling or hissing, which abruptly stops, this may indicate periodic movements of the plug inside the assembly.
A reliable method of checking is tactile control of the temperature of various parts of the circuit. Condenser (grid at the back) should be warm evenly, and the outlet from the capillary tube in front of the evaporator - cold. If the filter drier is colder than the environment or is covered with frost, this is almost guaranteed to indicate an obstruction to the freon flow.
- 🔊 The compressor hums, but no cold is generated, or the thermal relay is turned off.
- ❄️ The evaporator is covered frost unevenly or remains completely warm.
- 🌡️ The filter drier has a temperature significantly lower than room temperature (fogging).
- 🛑 There is no characteristic sound of freon escaping when the system is depressurized.
⚠️ Attention: If after prolonged operation The filter-drier compressor becomes hot, this may indicate a complete blockage of flow and the engine is operating in overload mode, which can lead to its combustion.
Necessary tools and materials for repair
High-quality cleaning is impossible without specialized equipment. The basic element is vacuum pump, which is necessary to remove moisture and air from the circuit before refueling. Without deep evacuation, any repair attempt is doomed to failure, since the remaining moisture will freeze again and clog the system.
To work with a gas environment, you will need a cylinder with nitrogen and a reducer. It is nitrogen that is used to purge the system under high pressure, since it is inert and does not react with oil or metal. You also need a kit manometer station to control the pressure during evacuation and refrigerant charging.
The most important step is the preparation of connections. You will need a pipe cutter, a rolling tool, and a torch with solder and flux. To flush the system from oxides and old oil, you will need a special solvent (for example, R141b or specialized flushing fluids). Do not use acetone or aggressive chemicals that can damage rubber seals or compressor windings.
To collect old refrigerant and oil, containers should be prepared. Working with freon requires caution, as it displaces oxygen and can be dangerous in confined spaces. All tools must be dry and clean so as not to introduce new contaminants into the system.
Preparing the refrigerator for cleaning the system
Before starting any work, the refrigerator must be completely disconnected from the power supply and defrosted. Even if there is visually no ice, moisture may be contained in the thermal insulation and evaporator. After defrosting, you need to gain access to the compressor compartment by removing the back panel or removing the start-up relay.
The next step is to release the residual refrigerant pressure. This is done through a puncture of the fitting or Schrader valve. Oilthat comes out along with the gas must be collected in a separate container to assess its condition: if it is black, has a burning smell or contains acid, the entire compressor will need to be flushed.
Next, tapping is carried out filter drier and capillary tube. The capillary is often soldered into the evaporator, so you need to unsolder it carefully so as not to damage the thin-walled heat exchanger tubes. If the capillary tube is glued to the evaporator body, it must be carefully separated by heating the gluing area with a hairdryer.
- 🔌 Disconnect the refrigerator from the network and provide access to the back wall.
- 🛢️ Drain the old compressor oil and evaluate its color and smell.
- 🔥 Unsolder the filter drier and capillary tube from the condenser and evaporator.
- 🧹 Prepare a place for working with an open fire, providing ventilation.
⚠️ Attention: When desoldering, use a damp rag to cool adjacent sections of the tubes so as not to melt the aluminum parts of the evaporator or the paint of the housing.
Methods of nitrogen purging and solvent flushing
The most effective way to clear a blockage is countercurrent nitrogen purging. To do this, nitrogen is supplied in the opposite direction: from the evaporator side to the condenser or directly into the capillary. The pressure during purging should not exceed 10-15 atmospheresso as not to rupture the tubes, but should be sufficient to push out the plug.
If simple purging does not help, the flushing method is used. solvent. The liquid is poured into the system, held to dissolve the oxides, and then purged with nitrogen. The procedure is repeated until the emerging liquid becomes clear. Particular attention is paid to to the capacitoras oil breakdown products often accumulate in its bends.
In difficult cases, when the blockage is caused by copper oxides (black deposits), repeated cleaning may be required flushing After flushing, the system must be dried with a vacuum pump.
Why can’t you blow out the system with a compressor?
Using the refrigerator compressor itself to blow through the system is strictly prohibited. The compressor is designed to compress freon vapor, and not to work with atmospheric air containing moisture. An attempt to blow through the system with a compressor will lead to moisture and oxygen getting inside the motor, which will cause oxidation of the windings, the formation of acid in the oil and rapid failure of the unit.
After successful blowing of all sections of the circuit, it is necessary to make sure that patency is restored. The air should pass through the capillary with a characteristic whistle, and form a powerful jet at the outlet. If the flow is weak, the procedure is repeated or a section of the capillary tube is replaced.
Replacing the filter-drier and vacuuming
The filter drier is a disposable element that must be replaced whenever the circuit is opened. Inside it is zeolite or silica gel, which absorbs moisture. If the filter is old, it is already saturated with moisture and will not be able to protect the system from ice blockage. The new filter is sealed immediately after removing the packaging to minimize contact with air.
After installing the new filter and assembling all connections, the vacuum stage begins. Vacuum pump connects to the service fitting, and the system is pumped out for 30-60 minutes. The goal is to reduce the pressure to a minimum (usually below 500 microns) in order to boil away all moisture from the oil and metal walls.
Tightness control is carried out using a pressure gauge: after closing the valve and turning off the pump, the arrow should not creep up. If the pressure increases, it means that there are microcracks in the system or poor-quality soldering. Nitrogen Under a pressure of 10-15 bar, you can use it to check for leaks by applying a soap solution to all seams.
| Work stage | Duration | Pressure / Parameters | Target |
|---|---|---|---|
| Nitrogen purge | 10-15 min | 10-15 atm | Removal of mechanical contaminants |
| Evacuation | 30-60 min | < 500 microns | Removal of moisture and air |
| Tightness check | 15-20 min | Stable vacuum | Search for leaks |
| Refrigerant charging | By scales | Norm according to the passport | Restoring the cycle |
☑️ Checklist before refueling
Only after successfully passing all leak tests can you proceed to filling the refrigerator with freon. Violation of the technology at this stage will negate all previous cleaning efforts.
Refrigerant charging and performance testing
Refilling is carried out strictly according to the weight indicated on the technical label of the refrigerator. Use electronic scales is mandatory, since “filling by eye” or by pressure often leads to incorrect operation. Freon is pumped in the liquid phase (if the type of refrigerant allows it) or in the vapor phase, monitoring every gram.
After starting the compressor, it is necessary to control temperature the condenser and evaporator. The condenser should heat up evenly from top to bottom, and the evaporator should feel cold. The suction pressure must correspond to the type of refrigerant (for R134a this is usually about 0.05-0.1 MPa in operating mode).
The final check includes observing the on and off cycles. The refrigerator should rise to temperature and turn off. If the compressor runs without interruption, perhaps the amount of freon is insufficient or there is air left in the system. Refilling or adding refrigerant is done carefully, in small portions.
⚠️ Attention: An excess of refrigerant is as dangerous as a deficiency. It can cause water hammer in the compressor or an increase in pressure in the system, which will lead to rupture of the tubes or activation of the safety valve.
After completion work, the puncture site of the service tube is sealed and the quality of the seam is checked. The refrigerator is left to work for several hours to stabilize the temperature in all chambers.
Common mistakes and preventive measures
One of the most common mistakes is ignoring the replacement of the filter-drier. Craftsmen often skimp on this element, believing that the old filter will “still work.” This leads to the fact that after a few weeks or months, the moisture accumulated by the filter enters the capillary, causing a repeat ice plug ice plug.
Another mistake is insufficient vacuuming time. Moisture in the system is the main enemy. If you do not remove it completely, it will react with oil and refrigerant, forming an acid that corrodes the metal from the inside. Oxidation pipes - this is an irreversible process without complete flushing.
To prevent blockages, it is recommended to avoid moisture entering the system during any repair. Store the removed parts in sealed silica gel bags. Also, you should not leave the system open to the air for a long time, since copper actively absorbs moisture from the atmosphere.
Regular maintenance, cleaning the condenser from dust and monitoring the condition of the door seals will help extend the life of the refrigerator and reduce the load on the compressor, minimizing the risk of oil overheating and carbon formation.
Is it possible to clean the capillary without nitrogen, using only compressor?
No, it is strictly forbidden to use a standard refrigerator compressor to blow the system with atmospheric air. This will saturate the system with moisture and oxygen, which will cause oxidation of the motor windings and the formation of acid in the oil. An inert gas (nitrogen) is required for purging.
How often do you need to change the filter-drier?
The filter-drier is changed every time the circuit is depressurized, the compressor is replaced, or moisture is detected in the system. This is a disposable element, the resource of which is not restored.
What to do if, after cleaning, the refrigerator stops freezing again?
Most likely, there is moisture left in the system or the blockage has not been completely removed. It is necessary to repeat the vacuum procedure with heating the filter (hairdryer) to evaporate moisture, replace the filter-drier and check the permeability of the capillary.
Is it dangerous to use solvents for washing?
Yes, many solvents are toxic and flammable. You need to work in a well-ventilated area, away from open fire, using personal protective equipment (gloves, goggles, respirator).
Can a new refrigerator become clogged?
Yes, if an error was made during installation (a tube was bent) or the vacuum was poorly done at the factory. Also, the reason may be a defective filter-drier or debris during assembly.