The lack of cooling in the refrigerator while the compressor is running often becomes an unpleasant surprise for the owner of household appliances. If the engine hums, but no cold is produced, or a huge block of ice freezes in one corner of the chamber, and there is heat in the other, there is a high probability of a blockage in the refrigerant circulation system. In such situations, craftsmen often talk about the need to clean capillary tubewhich is the “bottleneck” of the entire refrigeration system.
This part is a thin copper pipeline where liquid freon turns into vapor, taking heat from the chambers. The diameter of the channel is so small that even a microscopic particle of oxide or moisture that has turned into ice can completely block the flow of refrigerant. Independent flushing the system is a complex technical process that requires an understanding of the physics of the refrigeration circuit and the availability of specific tools.
Before taking active steps, you must clearly understand the risks. Working with refrigerants and the compressor under pressure requires caution. Improper cleaning can lead to depressurization of the circuit or moisture getting inside, which will require expensive refilling from professionals. However, if you are confident in your abilities and have basic repair skills, restoring the patency of the tube is possible at home.
Diagnostics of a blockage and how the system works
Understanding how it works refrigeration circuitis critical for successful repair. Freon circulates through a closed system, changing its state of aggregation. The capillary tube here plays the role of a throttle: it sharply reduces the pressure of the refrigerant before it enters the evaporator. It is in this place that a sharp expansion of gas and heat absorption occurs. If the permeability is impaired, the pressure does not drop and the cooling cycle stops.
The nature of the blockage can be determined by the external signs of the operation of the unit. There are two main types of plugging: oil-paraffin plugging and ice plugging. In the first case, thickened compressor oil or decomposition products mix with the refrigerant and clog the narrow channel. In the second case, the culprit is moisture that has entered the system, which freezes at the throttling point.
⚠️ Attention: If after defrosting the refrigerator within 24 hours the problem returns (ice freezes in one place), this is almost guaranteed to indicate an ice plug in the capillary due to moisture.
For accurate diagnosis Often it is necessary to open the system and install a pressure manifold. When the compressor is turned on, the suction pressure may be below atmospheric (vacuum), and the discharge pressure may be abnormally high. This indicates that the gas “stands” in the system and does not circulate. Sometimes a tactile check helps: if capillary tube it is hot at the entrance to the evaporator, but cold immediately after it, the plug is located in this place.
Necessary tools and preparation of the workplace
Quality blowing the capillary is impossible without specialized equipment. Attempting to clean the system with your mouth or a car pump will not work, since effective cleaning requires high pressure and the use of chemicals. The master's basic kit includes not only tools, but also consumables.
First of all, you will need a vacuum pump and a filling station with pressure gauges. Vacuuming is necessary to remove moisture and residual old freon before starting work. You will also need a torch (gas or oxy-acetylene) for soldering copper tubes and removing filter driers. Without the ability to hermetically seal the system after cleaning, all efforts will be in vain.
For direct cleaning, nitrogen or dry air under pressure, as well as special solvents, are used. In a professional environment, liquid R141b or analogs are often used that effectively dissolve oil deposits. It is important to prepare a container to collect used oil and dirty flushing fluid.
☑️ Repair tools
Mechanical and gas cleaning technology
There are several methods for restoring patency capillary tube. The most common and effective method is high-pressure nitrogen purging from the reverse side. The essence of the method is to create an impulse that pushes the clogged mass out of a narrow channel. Before starting the procedure, the filter-drier must be unsoldered and the capillary disconnected from the evaporator.
The process is as follows: a hose with nitrogen is connected to the inlet of the capillary (from the condenser side). The pressure is gradually increased to 10-15 atmospheres. If the plug is oily, it often comes out with a characteristic pop. To enhance the effect, you can use the “pneumatic shock” method by closing and sharply opening the gas supply valve. Sometimes it is necessary to repeat the procedure several times.
If simple purging does not help, the solvent washing method is used. A special liquid is poured into the tube, given time to dissolve the deposits, and then purged with nitrogen again. This method is more aggressive and requires careful subsequent drying of the system so that chemical residues do not damage the compressor windings or new seals.
Danger of using oxygen
Never use pure oxygen to purge the refrigeration system! When mixed with oil vapor inside the compressor, oxygen forms an explosive mixture. Even a spark from soldering or static electricity can cause the compressor to explode. Use only inert gases (nitrogen) or dried air.
Replacing the filter-drier and vacuuming
Any opening operation refrigerant circuit requires a mandatory replacement of the filter-drier. This small element, which is a copper cylinder with a mesh and sorbent inside, is responsible for retaining moisture and debris. When cleaning the capillary, a large amount of dirt and moisture passes through it, so the old filter is guaranteed to lose its properties.
After successfully cleaning the tube and installing a new filter, it is necessary to carry out a deep vacuum of the system. This step is critical for removing air and water vapor. The moisture remaining in the system will freeze again in the capillary during the first operation, and the blockage will form again. The evacuation time depends on the power of the pump and the volume of the system, but is usually at least 30-40 minutes.
The quality of evacuation is monitored using a pressure gauge. The arrow should go into the green zone (vacuum) and remain stable there after the pump is turned off. If the pressure begins to rise, this indicates leaking connections or the presence of moisture that evaporates at low pressure. In this case, the procedure must be repeated, possibly warming up the condenser and compressor with a hairdryer to accelerate the evaporation of moisture.
| Work stage | Action | Control parameter |
|---|---|---|
| Dismantling | Cutting filter, capillary tap | Tightness of the rest of the system |
| Purge | Nitrogen supply 15-20 atm. | Presence of output flow |
| Rinsing | Filling the solvent | Transparency of the exiting liquid |
| Assembly | Soldering a new filter | No leaks |
| Vacuum | Air pumping | Pressure below -0.98 bar |
Refrigerant charging and testing
The final stage of restoring the functionality of the refrigerator is refueling working gas. The amount of freon is strictly regulated by the manufacturer and is indicated on the factory tag (usually in grams). A lack of gas will lead to poor performance, and an excess will lead to increased energy consumption and possible water hammer in the compressor.
Refueling is carried out in two stages. First, start the compressor and gain about 80% of the norm, controlling the suction pressure. Then let the unit run for 10-15 minutes so that the gas is mixed with the remaining oil and distributed throughout the system. The remaining 20% is added based on the temperature of the evaporator and the current consumption of the motor.
⚠️ Attention: The type of refrigerant must strictly correspond to the labeling. Refilling R600a (isobutane) instead of R134a or vice versa will lead to failure of the compressor or a fire hazard, since isobutane is flammable.
To control the correctness of refueling, use current measuring ticks. The operating current of the compressor must correspond to the rating data for the specific model. They also check the temperature of the condenser (grid at the back) - it should be evenly hot over the entire area, without sudden changes, which indicates free circulation of gas.
Typical mistakes and precautions
Independent repair of refrigerators is fraught with risks, and even experienced craftsmen make mistakes. One of the most common problems is incomplete removal of moisture from the system. If you save time on vacuuming, after a week or two the ice plug will form again, and the entire procedure will have to be repeated.
Another common mistake is using an open flame near plastic parts or compressor insulation without proper protection. Copper has high thermal conductivity, and the burner flame can quickly spread to neighboring elements. Always use heat sink clips (crocodiles) made of copper or brass when soldering near plastic.
It is also worth mentioning the risk of pinching the tubes. The capillary tube is very thin-walled, and accidental clamping with pliers can completely block its passage. All manipulations with the tubes must be carried out carefully, without applying excessive bending forces.
Is it possible to clean the capillary without a nitrogen cylinder?
Theoretically, you can use a powerful compressor to inflate tires, but its pressure (usually up to 8-10 atm) may not be enough to break through a serious blockage. In addition, such air contains moisture and oil, which will only worsen the situation. The use of nitrogen is preferable, since it is inert and dry.
How much does it cost to replace a filter-drier?
The cost of the filter itself is low, but replacing it requires soldering, vacuuming and charging with freon. At the service center, this service is included in the cost of repairing the circulation system. You should buy a filter yourself with a reserve, since you cannot open it - it is disposable.
Why does the refrigerator freeze worse after cleaning?
Perhaps there is an excess amount of flushing liquid or oil left in the system, which disrupts heat transfer. Also, the reason may be poor-quality soldering, where the solder has sealed the passage hole of the tube, or an insufficient amount of refilled freon.