Faced with a breakdown of refrigeration equipment, many owners immediately think about calling a technician, but often the problem lies in the banal lack of lubrication in compressor. Independent addition or complete oil change can bring the unit back to life if the piston group is still intact. However, this process requires not only technical skills, but also strict adherence to technology, since the entry of moisture or air into the system is fatal for freon and the motor itself.
Before proceeding with dismantling, you must clearly understand that you are working with a sealed system under pressure. Refrigeration compressor is designed so that the oil circulates in it along with the refrigerant, and a violation of this balance leads to overheating and jamming. In this article, we will analyze in detail the process of preparation, selection of consumables and the refueling procedure itself, so that you can carry out repairs efficiently and safely.
It is worth immediately noting that the success of the operation depends 80% on the correct selection of the liquid. Using the wrong composition can lead to a chemical reaction, the formation of acids and rapid failure of the motor windings. Therefore, the first step is always to diagnose the current condition and determine the type of lubricant required.
Diagnosis of the need to replace the lubricant
You can determine that it is time to add or change the oil by the characteristic signs of the refrigerator. Users often confuse a lack of lubrication with a freon leak, but the symptoms of these problems can overlap, requiring careful analysis. If you hear a knock, a hum, or notice that the motor is overheating, these are the first signs.
Experienced technicians recommend paying attention to the following signs indicating a critical condition of the lubrication system:
- 🔊 The compressor makes a loud metallic clanging or buzzing sound, especially when startup.
- 🔥 The motor housing heats up to temperatures exceeding the norm (more than 90 degrees).
- ❄️ The refrigerator stops gaining temperature, although the condenser is hot.
- 🛑 The engine starts for a few seconds and turns off thermally relay.
⚠️ Attention: If black oil with a burning smell comes out of the tubes during depressurization, this indicates combustion of the windings. In this case, simply changing the oil will not help - the entire compressor needs to be replaced.
It is also important to check the condition of the oil visually, if it is possible to drain it through a capillary. Clean oil should be transparent or slightly yellowish, without mechanical inclusions. The presence of metal shavings indicates the destruction of the rubbing pairs, which makes further operation impossible without major repairs.
Choosing the appropriate type of oil
The key point in restoring performance is the right choice lubricant. Refrigeration equipment uses special synthetic or mineral oils that have a certain viscosity and chemical resistance to freon. The wrong choice will result in the oil either curdling or not returning to the compressor crankcase.
There are two main types of oils used in household refrigerators:
- 🧪 Mineral oils —used in older models with R-12 freon. They are not hygroscopic, but have lower temperature characteristics.
- 💧 Synthetic oils (POE, PEG) are necessary for modern refrigerators with R-134a, R-600a freons. They are extremely hygroscopic and require perfect tightness of the system.
To determine the type of oil that is already in the system, you can use a simple chemical reaction. Drop a little of the existing oil into the water: the mineral oil will form droplets on the surface, and the synthetic (polyester) will dissolve or form an emulsion.
Oil and refrigerant compatibility chart
Mineral oil (MO) is compatible with R-12 and R-22. Synthetic polyester oil (POE) is required for R-134a, R-404A, R-507. Mixing different types of oils is strictly prohibited, as this leads to the formation of sediment and acids.
When purchasing, pay attention to the viscosity, which is usually indicated by numbers (for example, 16, 22, 32). The higher the number, the thicker the oil. For household refrigerators, oils with a viscosity of 16 or 22 CST at a temperature of 40 degrees are most often used.
Necessary tools and preparation
A syringe alone will not be enough to carry out high-quality work. You will need to assemble a small set of tools that will allow you to create a vacuum and control the filling process. The lack of special tools can lead to air entering the system, which will cause the formation of plugs and oxidation.
The basic list of equipment for changing the oil includes:
- 🔧 Manometer station (manifold) for pressure control.
- 🌀 Vacuum pump - required to remove moisture and air.
- 💉 Large volume medical syringe (20-50 ml) or oil injector.
- 🔥 Gas burner or blowtorch for sealing tubes.
☑️ Preparation of the workplace
Also, do not forget to prepare containers for used oil and rags. Work should be carried out in a well-ventilated area, since freon vapor is heavier than air and can displace oxygen. Before starting work, make sure that you have access to the discharge and suction pipes of the compressor.
Technology for draining old oil
The process of removing used fluid requires care. In most cases, compressors are sealed and access to the internals is through cut tubes. First, you need to bleed off any remaining pressure, if it is still present in the system.
To drain the oil, perform the following steps:
- Cut the suction and discharge tubes of the compressor with pliers.
- Tilt the unit so that the oil flows through the open holes into the prepared container.
- To completely remove residues, you can purge the system with nitrogen, but at home it is enough to simply let it drain for 15-20 minutes.
The question often arises: is it necessary to flush the compressor? If the oil was black and smelled like burning, washing with a special solvent or the same type of fresh oil is required. If you are simply topping up the volume due to a small leak, flushing is not required.
⚠️ Attention: It is strictly forbidden to leave a compressor with synthetic oil (POE) open in air for more than 15 minutes. It instantly absorbs moisture from the atmosphere, which will lead to the formation of acid inside the system.
After draining, inspect the insides through the holes. If chips or carbon deposits are visible, more extensive cleaning or replacement of the assembly may be required. Cleanliness of the internal cavities is the key to long service after repair.
The process of filling with new oil
The most critical stage is pumping in a new portion of lubricant. You cannot simply pour oil through a funnel, as air will remain in the system. It is necessary to use the method of vacuuming or injection under pressure.
Consider two main methods of filling:
- 📉 Evacuation method: connect the vacuum pump to the suction tube, create a vacuum, then, without turning off the pump, open the oil supply valve. The vacuum itself will suck in the required amount of liquid.
- 💨 Pressure method: if there is no pump, you can use excess pressure in the system (if it is still charged with freon), but this method is less accurate and requires experience.
The amount of oil poured is strictly regulated by the manufacturer. Usually this is from 150 to 300 grams depending on the model. Overfilling is dangerous because liquid oil will enter the condenser, drastically reducing the efficiency of heat transfer and creating an oil plug.
Evacuating the system
After filling the oil, it is necessary to remove air and moisture vapor from the circuit. This stage is called vacuum. Without it, the operation of the refrigerator will be unstable, and corrosion processes will begin inside the system.
The process is as follows:
- Connect the vacuum pump to the service connection or suction tube.
- Turn on the pump and watch the pressure gauge.
- Keep the vacuum for at least 30-40 minutes. The pressure should drop to minimum values.
- Close the valve and turn off the pump. If the pressure gauge needle does not creep up within 10-15 minutes, the system is sealed.
Evacuation time directly depends on the power of the pump and the volume of the system. For household refrigerators, a pump with a capacity of 45-60 liters per minute is sufficient. If the pressure gauge needle creeps up after turning off the pump, it means there is a leak somewhere or the oil contains a lot of moisture, which evaporates in a vacuum.
Comparison of oil characteristics
To finally make your choice and understand the difference between types of lubricants, you should refer to the comparison table. This data will help you avoid mistakes when purchasing consumables in the store.
| Parameter | Mineral oil | Synthetic (POE) | Semi-synthetic (AB) |
|---|---|---|---|
| Compatibility with frequency hardening | R-12, R-22 | R-134a, R-407C, R-410A | Transitional mixtures |
| Hygroscopicity | Low | Very high | Average |
| Pour point | -30°C | -60°C and below | -45°C |
| Price | Low | High | Average |
As can be seen from the table, modern Synthetic oils have better characteristics, but require much more careful handling during storage and use. Mineral oils are more “forgiving” of mistakes, but become a thing of the past along with old refrigerants.
Common mistakes during repairs
Even experienced craftsmen sometimes make mistakes, let alone beginners. Avoid common mistakes so that you don’t have to redo the work or buy a new compressor.
The most common mistakes:
- 🚫 Ignoring evacuation: trying to simply add oil without creating a vacuum is doomed to failure.
- 🚫 Mixing types: adding mineral oil to synthetic system (and vice versa) will cause a chemical reaction.
- 🚫 Overflow: an oil level above normal will lead to water hammer and destruction of valves.
⚠️ Attention: Technical characteristics of compressors and requirements for oils may vary depending on the specific model and year of manufacture. Always check the technical documentation on the unit sticker before starting work.
They also often forget to check the filter drier. When changing the oil or compressor, it must be changed, since the old one could become saturated with moisture and stop working. Saving on this little thing will negate all efforts to change the oil.
In conclusion, it is worth saying that repairing a refrigerator yourself is a task for those who are ready for careful and painstaking work. If you doubt your abilities or do not have the necessary equipment (especially a vacuum pump), it is better to turn to professionals.
How much oil is needed for a typical home refrigerator?
The volume of oil varies from 150 to 350 grams depending on the power of the compressor. The exact quantity is indicated in the technical documentation or on the unit nameplate. A lack of oil will lead to overheating, and an excess will lead to a drop in performance.
Is it possible to use automobile motor oil?
Absolutely not. Automotive oils have different additives and viscosity; they are not designed to work in tandem with freon and at low evaporator temperatures. This will lead to rapid failure of the compressor.
How often do you need to change the oil in the refrigerator?
In a working sealed circuit, the oil is changed only during repairs (replacing the compressor or eliminating leaks). There is no planned replacement “based on mileage” like in a car in refrigerators, since the system is closed.
Why did the oil in the compressor turn black?
Blackening of the oil indicates overheating of the engine windings or moisture entering the system, which caused oxidation. This may also be a sign of destruction of internal parts (rubbing pairs).