The appearance of a stranger A humming sound, lack of cooling or a characteristic knocking sound in the compressor often signal a critical problem within the circuit. In such cases, craftsmen often decide on the need flushing the system refrigerator. This is a complex technical procedure that requires an understanding of the physics of the processes and the availability of specialized equipment for working with refrigerants.
The purpose of this operation is not just to remove visible dirt, but to completely free the tubes and heat exchangers from decay products compressor oil and acids. If you ignore this stage when replacing the motor, the new unit may fail in a matter of hours due to blockage of the capillary tube or coking of the valves.
In this article we will analyze in detail which liquids are really effective and which can cause irreparable harm. You will find out why regular pressure washing does not always save the situation and when a complete overhaul of the components is required.
Causes of contamination of the freon line
The main enemy of a sealed circuit is moisture that has gotten inside the system. This can happen due to poor-quality repairs, when the vacuum was not carried out for long enough or with violations of the technology. Interacting with residual refrigerant and oil, water forms aggressive acids that begin to corrode the metal from the inside.
The second factor is the thermal destruction of the lubricating fluid when overheated. compressor. If the motor was operated in extreme conditions or there was a breakdown of the winding, the oil turns into tar and varnish deposits. These substances settle on the walls of the tubes, gradually narrowing the flow area.
The so-called “acid disease” poses a particular danger. It occurs when the motor-compressor burns out in the system. The combustion products of insulation and oil are spread throughout the entire circuit, creating a conductive environment and abrasive particles.
⚠️ Attention: If, when opening the system, you feel a strong burning smell or see black flakes in the oil, simple flushing may not help. In such cases, it is often necessary to replace the filter drier and recirculate the flushing fluid.
Contamination can also be caused by poor-quality oil poured during production, or the use of an unsuitable refrigerant in the past. A mixture of mineral and synthetic oils (for example, POE and MO) almost always leads to the formation of a dense sediment, which it is impossible to dissolve without completely disassembling the system.
Choice of flushing liquid and equipment
The market offers many solutions, but not all of them are safe for refrigerator components. The most common, but controversial option remains Freon R11 or its modern analogues. However, due to environmental restrictions, their use is being reduced, and specialized solvents are coming to the fore.
For effective cleaning, they often use isopropyl alcohol or special aerosol air conditioner cleaners (for example, Divit or analogues). These liquids dissolve oily deposits well and evaporate quickly, leaving no moisture. It is important that the selected substance does not react with metal and rubber seals.
You should absolutely not use water, kerosene, gasoline or aggressive solvents like acetone. Water will cause corrosion and ice jams, and petroleum products will leave a sticky residue that cannot be removed. Gasoline can destroy the rubber gaskets of the compressor valves.
As for equipment, a vacuum pump and a pressure gauge station are needed for high-quality washing. Simply blowing with nitrogen is often not enough, since it does not dissolve acid deposits, but only blows out mechanical particles.
| Fluid type | Efficiency | Safety for rubber | Difficulty of disposal |
|---|---|---|---|
| Freon R11/R113 | High | Safe | High |
| Isopropyl alcohol | Medium | Safe | Low |
| Special. solvents (Divit) | High | Requires verification | Medium |
| Acetone/Solvents | High | Destroys | Average |
Preparation for the cleaning procedure
Before starting work, it is necessary to completely empty the system of refrigerant. This is done through a Schrader valve or by carefully cutting the tube away from the burner to avoid igniting the oil vapors. After relieving the pressure, the filter-drier and the compressor are dismantled. The system must be divided into sections for more efficient flushing. Usually the condenser, evaporator and capillary tube are sealed off. If the circuit is made of aluminum, you should be extremely careful with acid residues, since aluminum quickly oxidizes. compressor and filter drier.
The system must be divided into sections for more efficient flushing. Usually the condenser, evaporator and capillary tube are sealed off. If the circuit is made of aluminum, you should be extremely careful with acid residues, since aluminum oxidizes quickly.
It is important to prepare a container for collecting waste fluid. It will contain toxic substances and decomposition products, so it is prohibited to pour it into the sewer or onto the ground. Also make sure the area is well ventilated, as the vapors from many solvents are heavier than air and can cause suffocation.
⚠️ Attention: Before sealing any connections, make sure there is no excess pressure in the tubing. Use safety glasses and gloves, as oil residues may contain acid that is hazardous to the skin.
For work you will need: a torch, solder, a nitrogen cylinder with a reducer, a syringe or pump for pumping liquid, as well as a set of tubes of different diameters for organizing circulation.
Circuit flushing technology refrigerator
The cleaning process begins with the most contaminated unit - usually the condenser or compressor discharge tube. The liquid is poured or pumped under pressure in one direction, and then the system is purged with nitrogen to remove dissolved dirt.
The operation is repeated several times, changing the direction of flow. This allows you to wash out deposits from hard-to-reach places. For the capillary tube, the “pushing” method is used: they create pressure on one side and sharply release it, creating a hydraulic shock that knocks out the plug.
☑️ Checklist for flushing the system
If liquid nitrogen or dry ice is used for freezing residual moisture, this is done only after chemical washing. Cryogenic cleaning helps to remove microscopic particles that are not dissolved in chemistry.
Particular attention is paid oil separator (if it is structurally provided) to the suction line. This is where emulsion often accumulates, which can cause water hammer when starting a new compressor.
Master's secret
To check cleanliness, blow the system with a white cotton filter. If gray or black marks remain on the fabric, washing must be repeated. The ideal result is an absolutely clean cloth.
Cleaning and preparing a new compressor
Many craftsmen make the mistake of installing a new unit without preliminary preparation. Factory oil in new compressors often contains preservatives or may be mixed with residual moisture during storage.
It is recommended to carefully open the process pipe of the new motor and drain the factory oil. Then fill in fresh refrigerant corresponding to the type of refrigerant (POE for freon, MO for mineral systems), and turn the shaft several times to lubricate the rubbing vapors.
After this, the oil is drained again and checked for chips or cloudiness. If the oil is clean, the procedure can be considered complete. If wear debris is visible in the drain, repeat washing until it is in perfect condition.
Therefore, all manipulations with an open system must be carried out as quickly as possible.
⚠️ Attention: Never leave the compressor with open pipes in the air for longer than 10-15 minutes. This is guaranteed to lead to saturation of the oil with moisture and future corrosion.
After installing the motor on the frame and soldering the connections, but before refueling, the system must be vacuumized. The operating time of the vacuum pump should be at least 30-40 minutes to completely remove water and solvent vapors.
Assembly, vacuuming and filling
The final stage is sealing and filling the system with the working fluid. A new element is installed in place of the old filter-drier. It cannot be opened in advance, since the adsorbent will instantly begin to absorb moisture from the atmosphere.
Soldering of the new filter is done quickly, using a damp rag to cool the housing so as not to overheat the filler. The housing temperature should not exceed 100-120 degrees Celsius.
Evacuation is carried out until a residual pressure close to absolute vacuum is achieved (usually the pressure gauge needle goes into the blue zone or shows -1 bar). Then turn off the valve and watch the pressure gauge for 15-20 minutes. If the arrow creeps up, there is a leak in the system.
Refrigerant charging is carried out strictly according to the scale, guided by the sign on the refrigerator. Liquid freon is charged through the filter, and gaseous freon is charged through the suction pipe of the operating compressor, controlling the current and pressure.
Frequent errors and troubleshooting
One of the most common mistakes is insufficient nitrogen purging time. The technician sees that the liquid has leaked out and considers the unit clean, forgetting that dissolved dirty sludge remains in bends and dead-ends (blind spots).
Another problem is using the same volume of flushing fluid for the entire system. After the first flushing of the condenser, the solution becomes dirty, and there is no point in passing it through a thin capillary tube - you will simply clog it even more.
Sometimes they forget to replace the filter drier, relying on its “residual life”. This is a fatal mistake, since the old filter is already saturated with moisture and acid, which it will immediately release back into the clean circuit.
If after repair the refrigerator hums but does not cool, there may be an “air bag” left in the system or the solvent has not been completely removed, which, when boiling, creates high pressure that blocks normal circulation.
Is it possible to rinse refrigerator system with alcohol?
It is not recommended to use ordinary ethyl alcohol, as it is hygroscopic and can leave moisture. Isopropyl alcohol is acceptable, but it is less effective against acid deposits than specialized freon solvents or mixtures.
How many times should the system be flushed?
Minimum 2-3 flushing cycles with a complete replacement of the fluid and subsequent purging with nitrogen. In cases of severe contamination (“acid strike”), the number of cycles can reach 5-7.
What is the danger of poor evacuation?
Residual moisture in the system freezes in the capillary tube, forming an ice plug, which stops the circulation of freon. Also, water causes corrosion of metal and destruction of oil.
Is it necessary to flush a new compressor?
Yes, it is advisable. Factory-made oil may contain preservatives or oxidation products during long-term storage. It is better to replace it with a fresh one that matches the type of refrigerant.