How to refill a Zyl refrigerator: choosing refrigerant and oil

Owners of Soviet and post-Soviet equipment are often faced with the need to restore the performance of units that have served for decades. If your Zil refrigerator stopped freezing, and diagnostics showed a gas leak or compressor failure, you will be faced with the question of choosing the right consumables. Incorrect selection of refrigerant or lubricant can lead to final failure of the unit, so it is important to clearly understand the technical characteristics of your model.

The modern market offers many analogues, but older units require a specific approach. In this article we will look at which brands Freon are used in various modifications, what kind of oil is needed to lubricate the piston group and what are the refueling standards. We will also touch on the topic of safety, since working with gases under pressure requires strict adherence to the rules.

Identification of the model and type of refrigerant

The first step before any repair attempt is to accurately determine the model of your device. The Likhachev plant has been producing equipment for many years, and different ones were used in different periods. Most often, in old Soviet models, such as series refrigerants. Most often in old Soviet models, such as the series ZIL-63 or ZIL-64, R12 (dichlorodifluoromethane) was used. This substance had excellent refrigeration properties, but was banned for production due to its destructive effect on the ozone layer.

Later models released in the 90s and in the early 2000s, they could be equipped with compressors running on R134a (tetrafluoroethane). This gas is considered more environmentally friendly, but requires different oils and has excellent physical properties. An attempt to fill a model designed for R12 with R134a gas without changing the oil and throttling device (capillary tube) will lead to incorrect operation of the system.

To avoid mistakes, carefully study the technical data sheet or plate on the back wall of the unit. The type of refrigerant and its mass are indicated there. If the plate is unreadable, you can focus on the year of manufacture: until the mid-90s, almost all models worked on R12, after which R134a was more common.

⚠️ Attention: Mixing different types of freons is strictly prohibited! This leads to a chemical reaction, the formation of acids and complete blockage of the capillary system, which will damage the compressor in a matter of minutes.

Modern experts often suggest replacing the old R12 with R600a (isobutane), but this requires a complete re-soldering of the system and replacement of the compressor with a modern one, since isobutane is explosive and requires other safety measures during installation.

Characteristics of freon R12 and its analogues

If you are the owner of a classic Zil refrigerator era USSR, then with a 99% probability you will need R12. This gas is inert, non-flammable and non-toxic under normal conditions, but upon contact with an open flame it decomposes to form phosgene, a chemical warfare agent. Therefore, any work with soldering pipes after complete removal of the refrigerant from the system.

Since the production of R12 has been stopped all over the world, it is almost impossible to find a new cylinder. There are only reduced gases or counterfeit mixtures on the market. As an alternative, a mixture of R406A or pure R134a is often used for repairs, but this requires qualification. R134a operates at a higher pressure, which can be critical for old condensers designed for 10-12 atmospheres.

When using analogues, it is necessary to take into account that they may be incompatible with rubber seals of the old design. Some synthetic oils paired with new gases can corrode old gaskets, causing repeated leakage.

The use of substitute blends such as R406A is often marketed as a “no flush” solution. However, experts agree that for long-term operation compressor Zil it is better to completely evacuate and replace the filter element, even if a “compatible” gas is used.

Oil for the compressor: selection and replacement

Lubrication in the refrigerator does not only function of reducing friction, but also ensures the tightness of the gaps between the piston and the cylinder, and also removes heat from the rubbing parts. For Zil refrigeratorsworking on R12 freon, mineral oil was traditionally used. The most common brands were HF 12-16 and HF 22-18.

The main rule: mineral oil cannot be mixed with synthetic oil (polyester - POE), which is used with R134a freon. When mixed, a thick precipitate is formed, which instantly clogs the capillary tube. If you are switching to R134a, the old oil must be completely removed by flushing the system with nitrogen or new synthetic oil.

Oil viscosity also matters. Oil that is too thin will not create the desired film, which will lead to scuffing, while oil that is too thick will make pumping difficult and increase the load on the electric motor. For household refrigerators Zyl, the optimal ISO viscosity is considered to be in the range of 15-22.

⚠️ Attention: Never leave the compressor open in the air for more than 15-20 minutes. Mineral oil is hygroscopic and quickly absorbs moisture, which in the system will turn into an ice plug or acid.

If you are replacing the compressor with a modern analogue, make sure that it is already filled with oil. Often modern units are supplied with synthetic oil already pumped under R134a. In this case, using the old R12 is impossible without thorough flushing.

Filling standards and control of the amount of refrigerant

The amount of refrigerant is a critical parameter. A lack of gas will lead to the fact that the evaporator will not freeze completely, and the compressor will work without stopping, trying to gain temperature. Excess freon is even more dangerous: liquid refrigerant can enter the compressor cylinder, causing water hammer and mechanical destruction of the valves.

The exact mass of refrigerant is indicated on the nameplate (metal plate) inside or behind the refrigerator. For different Zil models it varies from 140 to 250 grams. Filling "by eye" or by pressure in old single-chamber models with a capillary tube is unacceptable, since the pressure depends on the ambient temperature.

Professional filling is carried out on a scale with an accuracy of 1 gram. The technician weighs the cylinder before and after filling, controlling the mass of the substance injected. At home, it is almost impossible to achieve proper operation without scales.

Technological process of refueling with your own hands

If you decide to carry out repairs yourself, you will need specialized tools: a vacuum pump, a pressure gauge station, scales and a burner. The process begins with removing any remaining old gas. You can’t just bite off the tubes - the gas must be vented through a punctured fitting or valve to avoid moisture getting inside during vacuum.

The next step is soldering and installing a new filter-drier. The filter must be changed whenever the circuit is opened, since the old silica gel is already saturated with moisture and will not be able to work effectively. After soldering, the system is filled with nitrogen under a pressure of 10-15 atmospheres to check for leaks. A soap solution will help identify air bubbles in the soldering areas.

Sequence of actions:
1. Vent the remaining gas.
2. Replace the filter drier.
3. Purge the system with nitrogen.
4. Vacuum for 30-40 minutes (up to -1 atm).
5. Fill with freon according to the scale.

Evacuation is the most important stage. It is necessary to remove air and water vapor. Water in the system freezes at subzero temperatures and clogs the capillary. The vacuum pump must run for at least 30 minutes, and ideally an hour, to evaporate all the moisture from the oil and the walls of the tubes.

Why can’t you refill without a vacuum?

If the air is not removed, an air lock will form in the system. Air does not condense at operating temperatures, occupying the volume of the condenser. This sharply increases the discharge pressure, the compressor overheats, and the refrigerator stops freezing.

Problems after refueling and their solution

Even if all standards are followed, difficulties may arise. If the refrigerator turned on, worked for 10-15 minutes and turned off via the thermal relay, the capillary may have become clogged or there was an excess of oil in the system. Old Zyl compressors often “drive” oil along with gas, which disrupts heat transfer.

If the freezer is working, but the refrigerator is warm, or vice versa, these are signs of incorrect dosage or a problem with the thermostat. It is also worth checking the door seals: if they are dry, the cold will leave, and no amount of refilling will help.

Noisy operation of the compressor after repair may indicate that moisture or air has entered the system. In this case, repeated evacuation and refueling is required. Sometimes installing an additional noise muffler on the suction tube helps.

⚠️ Attention: If after refueling the tube at the outlet of the compressor (discharge) becomes red-hot or becomes too hot (more than 80-90 degrees), turn off the device immediately. This is a sign of working at a “vacuum” or the presence of air in the system.

Frequently asked questions (FAQ)

Is it possible to fill a ZIL refrigerator with R134a automotive freon?

Technically this is possible, but requires a complete oil change in the compressor to synthetic (POE) and, preferably, replacing the capillary tube with a longer or thinner one. Simply replacing the gas without flushing the system will lead to the formation of acid deposits and rapid failure of the compressor.

Where can I get R12 freon for an old refrigerator?

R12 is not officially produced. It can only be found in stock from old masters or on the secondary market (used cylinders), which is risky. Most often, specialists suggest switching to a substitute gas R406A, which is compatible with mineral oil and does not require complex reworking of the system.

How much does it cost to refill a Zyl refrigerator at the service?

The cost consists of the work of the specialist, the cost of the refrigerant and the cost of travel. On average, the price varies from 2,500 to 5,000 rubles, depending on the region and the complexity of access to the nodes. Repairing older models is often not economically feasible if a compressor replacement is required.

Why does the refrigerator freeze after refilling, but does not turn off?

This may indicate a freon leak (refilling was a temporary measure), a malfunction of the thermostat, or loss of door tightness. Also, the reason may be a clogged capillary tube when the pressure in the system is not equalized.