The question of how to refill the refrigerator compressor often arises among owners of household appliances who are faced with a drop in cooling efficiency or complete failure of the unit. Sealed circuit A refrigerator is a complex system where each component plays a critical role, and an error in choosing consumables can lead to irreversible consequences. Many self-taught craftsmen mistakenly believe that it is enough to simply add “some oil,” but the reality is much more complex and requires a deep understanding of the physics of the processes.
Incorrectly selected lubricant or refrigerant can literally jam the piston group in a matter of minutes of work, turning an expensive repair into a complete replacement of the unit. In this article we will analyze in detail the types of oils, their compatibility with various refrigerants, as well as technical nuances that must be taken into account before starting work. Understanding these principles will help you avoid fatal mistakes when servicing equipment.
Types of oils for compressor units
The basis for the durability of any compressor is high-quality lubrication of rubbing parts. In household refrigerators, mainly two types of liquids are used: mineral and synthetic oils. Mineral oils, obtained by direct distillation of oil, were traditionally used in older models of refrigerators running on R12 and R22 freons. They have good hygroscopicity, but have one significant drawback - a high pour point and low chemical stability when in contact with modern refrigerants.
With the advent of environmentally friendly refrigerants, such as R134a and R600a, The industry has switched to the use synthetic oils, in particular polyester (POE). The chemical structure of synthetics allows it to effectively dissolve in new types of freons, ensuring the return of lubricant to the compressor crankcase. If mineral oil gets into a system designed for synthetics, it will not be able to circulate along with the gas and will settle in the heat exchangers, which will lead to overheating and breakdown.
It is important to understand that mixing different types of oils is strictly prohibited. A chemical reaction between the mineral and synthetic base can lead to precipitation, which will clog the capillary tube. Viscosity The oil is also selected strictly in accordance with the requirements of the manufacturer, since a liquid that is too thick will create excessive resistance, and a liquid that is too thin will not be able to create a protective film.
- 🛢️ Mineral oils —suitable only for old systems on R12/R22, highly hygroscopic.
- 💧 Polyester oils (POE) —standard for modern refrigerators, require tightness during storage.
- ⚗️ Alkylbenzene oils (AB) —an intermediate option, sometimes used as a replacement for mineral oil, but less common.
⚠️ Attention: Synthetic oil is hygroscopic, that is, it instantly absorbs moisture from the air. An open canister must be used immediately, otherwise the oil will lose its properties and become an acid that corrodes the motor windings.
Compatibility of oils and refrigerants
The choice of lubricant is inextricably linked to the type of refrigerant used. The physicochemical properties of freon determine whether the oil can dissolve in it and return back to the compressor. In old systems where it was used, mineral oils were used, since this freon mixed well with oil fractions. However, modern environmental standards have required a transition to new gases that are not friendly with mineral water. R12, mineral oils were used, since this freon mixed well with petroleum fractions. However, modern environmental standards have required a transition to new gases that are not friendly with mineral water.
For refrigerants of the R134a and R600a (isobutane) series, the use of polyester oils is a prerequisite. These synthetic liquids have the unique ability to remain in solution with the gas even at low evaporator temperatures. If you ignore this rule and fill in an incompatible component, the oil will settle in the “warm” part of the system, disrupting heat exchange and causing the compressor. oil starvation compressor.
There are also special transition oils and additives that theoretically allow the use of a mineral base with new freons, but professional craftsmen recommend avoiding such compromises. The reliability of the system directly depends on the purity and homogeneity of the working mixture. Any experiments with “hybrid” solutions can reduce the service life of the unit by several times.
| Refrigerant type | Recommended oil | Base type | Features |
|---|---|---|---|
| R12, R22 | Mineral Oil | Mineral | Requires careful drying of the system |
| R134a | Polyol Ester (POE) | Synthetic | Hygroscopic, aggressive to some plastics |
| R600a (Isobutane) | Polyol Ester (POE) | Synthetic | Explosive, requires special care |
| R404A, R507 | Polyol Ester (POE) | Synthetic | Used in industrial cold |
What happens if you mix R134a and mineral oil?
The mixture will stratify: the gas will go to the upper part of the system, and the oil will settle in the lower part. The compressor will start to run “dry”, which will lead to jamming of the pistons after 10-20 minutes of operation.
The process of changing the oil in the compressor
Changing the oil is not just “drained and filled”, but a technically complex procedure that requires evacuation of the system. Before filling the compressor with new oil, it is necessary to completely remove any remaining old fluid and, more importantly, moisture. The process begins with dismantling the compressor or, in some cases, through the service pipe, if the design allows complete drainage.
After draining the waste, a special one is pumped into the system solvent for flushing the circuit, which is then also removed. A critical step is to create a deep vacuum using a vacuum pump. The residual pressure should be minimal to exclude the presence of air and water vapor, which form aggressive acids when in contact with synthetic oil.
Filling of new oil is carried out strictly according to the weight indicated on the compressor nameplate or in the service documentation. Overfilling the oil will lead to water hammer and release of lubricant into the condenser, and underfilling will lead to rapid wear of the bearings. For accurate dosing, special syringes or scales are often used.
☑️ Oil change checklist
Do not forget that in some modern models the compressors are supplied already filled with oil, and their design does not imply maintenance. In such cases, the complete assembly is replaced.
Filling with refrigerant: choosing freon
After changing the oil, the stage of filling the system with refrigerant begins. Here the choice is between the original type of gas specified by the manufacturer and its analogues. The most common question is the possibility of replacing R12 with R134a or R600a. Technically, such a transition is possible, but it requires a complete re-soldering of the system, replacement of the filter-drier and, as we have already found out, a complete oil change.
Modern refrigerators most often operate on isobutane (R600a). It is a natural gas that has excellent refrigeration properties, but is flammable. Working with it requires compliance with the strictest safety measures: no sparks, open flames and the use of non-sparking tools. The concentration of gas in the air in the event of a leak can create an explosive mixture.
For refilling, cylinders with the appropriate gas, a pressure gauge station and scales are used. The amount of refrigerant is measured in grams with an accuracy of 1-2 grams. An excess of freon will lead to an increase in condensation pressure and overload of the compressor, and a deficiency will lead to inefficient operation and overheating of the motor.
- ❄️ R134a —safe, does not burn, but requires synthetic oil and careful evacuation.
- 🔥 R600a —effective, environmentally friendly, but explosive, requires professional equipment.
- 🚫 R12 —prohibited for production, used only when repairing old equipment.
⚠️ Attention: When working with R600a, be sure to ventilate the room. Do not solder pipes if there is gas left in the system - this is a guaranteed explosion.
Tools and equipment for refilling
Quality refilling compressor installation is impossible without specialized tools. The master’s basic kit includes not only a gas cylinder and oil, but also a whole arsenal of devices for controlling the process. The first and main tool is vacuum pump. It is this that allows you to remove moisture from the system by lowering the boiling point of water to room temperature and evaporating it.
The second element is a pressure gauge station (collector). It allows you to control the pressure in the high and low pressure circuit, and also serves to connect a vacuum pump and a refrigerant cylinder. For accurate dosage of gas and oil, electronic scales with a measurement step of 1 gram are required. The use of an “eye gauge” or approximate values is unacceptable.
You will also need pipe cutters, rolling, a torch for soldering copper pipes (preferably with an oxygen-propane mixture or MAPP gas) and a leak detector. A leak detector is necessary to check the tightness of the assembled system before startup. Any, even microscopic, leak will negate all efforts to change oil and freon.
Minimum required tools:1. Pressure manifold
2. Vacuum pump (2-stage)
3. Electronic scales
4. Pipe cutting and rolling
5. Burner and solder
6. Leak detector
Frequent errors and precautions
Even knowing the theory, beginners often make mistakes that cost them a new job compressor. One of the most common is neglect of replacement filter drier. This element is disposable and when the circuit is opened, it instantly absorbs moisture from the air. If you do not replace the filter, it will begin to release moisture back into the system, which will lead to the formation of an ice plug in the capillary and corrosion.
Another mistake is insufficient vacuuming time. Many people think that 5-10 minutes is enough, but it takes at least 30-40 minutes of pump operation to remove moisture from the synthetic oil and the walls of the tubes. The cleanliness of hands and tools is also often ignored: dust or dirt getting into the circuit can clog the capillary tube.
Do not forget about the temperature regime. Soldering must be done quickly and carefully, without overheating the pipes, so as not to disturb the structure of the solder or damage the insulation of the windings inside the compressor. Using the wrong solder (for example, tin instead of silver or phosphorus) is also a gross mistake.
- 🚫 Forgot to replace the filter drier - moisture will kill the compressor.
- 🚫 Poorly pumped out the vacuum - ice plug and oil acidity.
- 🚫 The pipe was overheated during soldering - narrowing of the channel or burn-through.
⚠️ Attention: Technical characteristics and requirements for oils may vary depending on the specific refrigerator model. Always check the manufacturer's official documentation before starting work.
FAQ: Frequently Asked Questions
Is it possible to mix oil from different manufacturers for a compressor?
It is strictly not recommended. Even if the oil base is the same (such as POE), different additives and additive packages from different manufacturers can react to form flakes or acid. It is better to use one brand of oil or completely flush the system when changing brand.
How much oil should be poured into the refrigerator compressor?
The exact volume of oil is indicated on the compressor nameplate or in the service documentation (usually from 200 to 400 ml for household models). Filling “by eye” or on a residual basis is unacceptable, since the oil level affects hydraulics and lubrication.
What is the danger of moisture getting into a system with synthetic oil?
Polyester oils (POE) undergo hydrolysis upon contact with water. As a result of this chemical reaction, alcohols and, most dangerously, organic acids are formed. These acids corrode the varnish insulation of the electric motor windings and metal parts, leading to short circuits and jamming.
Is it possible to fill a refrigerator with R134a instead of R12 without changing the oil?
No, it is not possible. R134a does not dissolve in mineral oil, which was used for R12. The oil will not return to the compressor, causing it to fail. To switch to R134a, you need to completely flush the system, change the oil to synthetic and replace the filter-drier.