Modern household Refrigerators are designed by engineers as sealed systems designed to last a lifetime without the need for maintenance. However, real operating conditions, power surges or factory defects can lead to a situation where compressor it fails or requires replacement of the lubricant. Owners who are faced with a hum, overheating of the unit or refusal to start often wonder about the possibility of independently intervening in the design of the motor.
The process of changing the oil in a refrigerator compressor is a complex technical procedure that requires not only special tools, but also a deep understanding of the principles of operation of the refrigeration circuit. It is important to note right away: in most cases, the factory instructions prohibit opening the sealed compressor casing. However, there are scenarios when such an operation becomes the only way to extend the life of a unit or revive an expensive unit without purchasing a new one.
Before taking active steps, you need to soberly assess your strengths and the availability of equipment. If your refrigerator is under warranty, any tampering with the system Freon circuit automatically voids the manufacturer's obligations. This article is for informational purposes only and describes the technical aspects of the process for specialists and enthusiasts who are ready to take responsibility for the result.
The design of the compressor and the role of lubrication
The compressor is the heart of the refrigeration unit, ensuring the circulation of refrigerant throughout the system. Inside a sealed metal casing there is an electric motor and a piston or rotor group, which experience enormous mechanical loads during operation. To reduce friction and heat removal, a special one is used, which is located in the lower part of the housing (crankcase). compressor oil, which is located in the lower part of the housing (crankcase).
The lubricating fluid not only reduces friction, it also seals the gaps between the piston and the cylinder, preventing compressed gas leaks. Unlike car engines, here the oil is constantly in contact with the coolant and is under high pressure. That is why the most stringent requirements are imposed on its chemical composition: it must have a certain viscosity, a low pour point and complete chemical inertness towards freon.
Modern systems use two main types of oils: mineral and synthetic (polyester). Mineral compositions were used in older models with R12 freon, while POE synthetic oils (Polyol Ester) are designed specifically to work with modern refrigerants R134a and R600a. It is absolutely impossible to confuse them, since they have different chemical bases and do not mix with each other.
⚠️ Attention: An attempt to replace synthetic oil with mineral oil (or vice versa) without thoroughly flushing the system will lead to the formation of acidic compounds, which in a matter of days will destroy the engine windings and clog capillary tube.
The tightness of the system is a key factor in durability. Any entry of moisture from the atmospheric air into the compressor during an oil change can be fatal. Moisture reacts with the refrigerant and oil, forming aggressive acids that cause corrosion of internal parts and breakdown of the electric motor insulation.
Diagnostics: when an oil change is necessary
It is almost impossible to determine the need to change the oil in a refrigerator compressor “by ear” or visually without opening it, since the system is sealed. However, there are indirect signs indicating degradation of the lubricating fluid or a critical decrease in its level. Most often, the problem lies not in the aging of the oil itself, but in its leakage or contamination with decay products.
One of the main symptoms is compressor overheating. If during operation the motor body heats up to temperatures at which it is impossible to hold your hand (above 80-90°C), this may indicate insufficient cooling due to lack of oil or loss of its properties. Also, a problem is indicated by a change in the nature of the unit’s operation: the appearance of a metallic knock, clanging or humming that was not there before.
Another sign is difficulty starting. The starter tries to start the engine, the relay clicks, but no rotation occurs, or the shaft turns with difficulty. This indicates that the oil has thickened, oxidized, or its level has dropped below a critical level, which is why the piston group is running dry.
It is also worth considering the age of the equipment. If the refrigerator is more than 15-20 years old, the oil inside could lose its properties simply from time to time, even if the device was idle. In such cases, a preventative replacement may be justified, but only if you have the appropriate equipment to evacuate the system.
Selecting the appropriate type of oil
The correct selection of lubricant is 90% of the success of the operation. As already mentioned, modern refrigerators operate on different types of refrigerants, and each of them requires a strictly specific type of oil. Using an unsuitable liquid will lead to rapid failure of not only the compressor, but also the entire refrigeration system.
For refrigerants of the freon group (R12, R22), which were used in Soviet and post-Soviet technology, mineral oils are used. They have good lubricity, but do not mix well with new refrigerants. For modern environmentally friendly refrigerants (R134a, R404A, R600a), synthetic polyester oils (POE) are used. They are hygroscopic, that is, they actively absorb moisture from the air, which requires special care when working.
Below is a table of correspondence between types of oils and refrigerants, which will help you not make a mistake with your choice:
| Refrigerant type | Type of required oil | Features | Examples of brands |
|---|---|---|---|
| R12, R22 | Mineral (MO) | Not hygroscopic, compatible with paraffin | HF 12-16, Suniso 3GS |
| R134a, R404A | Synthetic (POE) | Hygroscopic, requires vacuuming | Emkarate RL, Bitzer BSE |
| R600a (Isobutane) | Synthetic (POE) or Mineral | Depends on the compressor model, more often POE | Danfoss 12001477 |
When buying oil, pay attention to the viscosity. It is indicated by numbers (for example, 16, 22, 32). The higher the number, the thicker the oil. In household refrigerators, oils with ISO viscosity of 16 or 22 are most often used. Using too thick oil will make it difficult to start the engine in winter, and too thin will not create the necessary friction film.
Is it possible to mix different oils?
Mixing mineral and synthetic oils is strictly prohibited. Even small amounts of mineral oil in synthetics (POE) can cause sludge and loss of lubricity. If you switch from one type to another, multiple flushing of the system is necessary.
Necessary tools and preparation
To carry out a high-quality oil change, desire and a set of wrenches will not be enough. You will need specialized equipment that allows you to work with pressurized sealed systems. Without it, the operation will turn into a crude intervention with an unpredictable result.
First of all necessary vacuum pump. It is needed to remove air and moisture from the system before refueling. You will also need a pressure gauge station (manifold) to control pressure, a torch for soldering copper tubes (if you plan to open the circuit) and scales for accurate dosage of oil and freon.
- 🛠️ Tool set: wrenches, pliers, pipe cutter, rolling.
- 🧪 Chemistry: solvent for washing (for example, isopropyl alcohol or a special flush solution), nitrogen for purging.
- 🧤 Consumables: new filter drier (required!), solder, flux, rags.
Preparation The workplace also plays an important role. Ensure that the area is well ventilated as refrigerant and solvent vapors may be harmful to health. Prepare a container in advance for draining used oil and take care of the disposal of chemical waste.
⚠️ Attention: The filter drier is a disposable item. If the refrigerator circuit is opened in any way, it must be replaced. The old filter is already saturated with moisture and will not be able to protect the system from corrosion.
Do not forget to turn off the power to the refrigerator before starting work. Disconnect the device from the network at least 30 minutes before starting disassembly so that the capacitors have time to discharge and the pressure in the system is equalized.
Step-by-step instructions for changing the oil
The process of changing the oil in a refrigerator compressor requires consistency and accuracy. Violation of technology at any stage may lead to the need to replace the entire compressor unit. Let's consider the algorithm of actions for a situation where the compressor is dismantled or has access through the service pipe.
The first step is always the removal of old oil. If the compressor is removed, it must be turned over and the waste must be drained through the suction tube into a prepared container. The process may take from 15 to 30 minutes. To speed up the removal of residues, you can flush the system with dry nitrogen or use a vacuum pump to create a vacuum.
The next step is a critical step - flushing. A special flushing solvent is poured into the compressor through the pipes. The compressor needs to be rocked from side to side so that the liquid washes the internal walls, and then drained again. This procedure is repeated until the drained liquid becomes clear.
☑️ Checklist before starting
After washing, the solvent must be completely removed. To do this, connect the compressor to a vacuum pump and pump out the air for 30-60 minutes. The remaining solvent will evaporate under vacuum. If you ignore this step, chemical residues will mix with the new oil and ruin its properties.
Refilling with new oil is done through the suction pipe using a syringe or a special dispenser. The amount of oil is strictly regulated by the manufacturer (usually from 150 to 300 grams). Overfilling oil is just as dangerous as underfilling: excess fluid can cause water hammer or worsen heat transfer in the condenser.
After filling the oil, the seal of the casing should be restored. If the compressor has been disassembled, a new gasket is installed and the cover is tightened with bolts. Then the entire refrigerator system is evacuated, charged with freon and checked for leaks with a soap solution.
Common mistakes and precautions
Independent repair of refrigerators is fraught with risks, and beginners often step on the same rake. Understanding common mistakes will help you avoid costly rework and wasted time. The main mistake is neglecting vacuuming.
Many amateur craftsmen believe that it is enough to simply drain the old oil and fill in new oil. However, air that contains moisture remains in the system. When the compressor operates, moisture freezes in the capillary tube, forming an ice plug, or reacts with the oil, creating acid. This leads to clogging of the system and combustion of the motor.
Another common mistake is the use of inappropriate solvents for flushing. Aggressive chemicals can corrode the rubber seals inside the compressor or the varnish insulation of the motor windings. Always use only those products that are recommended by the refrigeration equipment manufacturer.
It is also worth mentioning the danger of working with an open flame when soldering tubes. Household refrigerators often use flammable freon R600a. Before soldering, you must thoroughly ventilate the room and make sure that the gas concentration in the air is minimal.
⚠️ Attention: Never try to start the compressor if the system is not charged with freon or is under vacuum. This will lead to instant overheating and jamming of the piston group due to lack of cooling and lubrication.
Answers to frequently asked questions (FAQ)
Is it possible to change the oil in a compressor without soldering the tubes?
Theoretically, you can try to pump out the old oil through suction tube with a syringe and fill in a new one, but the effectiveness of this method is extremely low. You will not be able to thoroughly flush the insides of the compressor and remove all waste. A full replacement requires opening the system.
How often do you need to change the oil in the refrigerator?
Under factory conditions, the oil in the refrigerator compressor is designed for the entire service life (10-15 years or more). Planned replacement is not provided. The oil is changed only when the compressor is repaired, moisture gets into the system, or after a long period of equipment downtime.
What happens if you fill in automobile engine oil?
It is strictly forbidden to use automobile oils. They have other additives, are not intended for contact with freon and at high temperatures can foam or coke, which will lead to jamming of the compressor after a short time.
Where can I find information about the amount of oil for my compressor?
The exact amount of oil is indicated on the manufacturer's label, which is often glued to the compressor itself (metal cylinder). This data can also be found in the service documentation (service manual) for a specific refrigerator model.
Is it possible to mix mineral and synthetic oil in an emergency?
No, they cannot be mixed even in an emergency. They are chemically incompatible. If you don’t have the right type on hand, it’s better to leave the old oil (if it hasn’t burned) and order the correct one, rather than risk costly repairs to the entire system.