How to disassemble a Soviet compressor from a refrigerator

Soviet refrigeration equipment is deservedly famous for its “indestructibility”, but time takes its toll, and even legendary units fail. Owners of rare Biryusa, ZIL or Saratov models are often faced with the need to replace or repair compressorwhich is the heart of any refrigeration machine. Disassembling this unit is a delicate process, requiring not only physical strength, but also an understanding of the principles of operation of high-pressure freon circuits.

Before taking active steps, you need to realize that inside the case there is oil under residual pressure, as well as refrigerant vapors, which can be dangerous when inhalation in a confined space. Proper preparation of the workplace and the availability of specialized tools are the key to a successful and, most importantly, safe dismantling operation. In this article we will analyze in detail all the stages of opening the sealed casing, removing the electric motor and piston group.

It is worth noting that complete disassembly unit is most often required for in-depth diagnostics or alteration of the compressor for other needs, for example, to create a compressor station. If your goal is simply to replace a burnt-out motor in a refrigerator, then you usually do not need to open the casing; it is enough to replace the entire assembly. However, for enthusiasts and craftsmen seeking to restore a rarity or understand the internal structure, this information will be extremely useful.

Necessary tools and precautions

Working with sealed units of old refrigerators is associated with risks associated with both mechanical damage and chemical safety. First of all, you need to make sure that freon is completely erased from the system. Even if the refrigerator has not been used for years, pressure may remain in the pipes. Pierce the tubes in a well-ventilated area or outdoors, away from open fire, since some types of refrigerants mixed with air can form flammable compounds.

For high-quality disassembly, you will need a set of plumbing tools, which is best prepared in advance so as not to be distracted during the process. Pay special attention to the cutting tool, since the factory welding of the casing is done very well and it is rarely possible to knock it off the first time.

• 🔨 A hammer and chisel or an old chisel - for carefully knocking down the weld along the equator of the body.
• 🔧 A set of wrenches and screwdrivers - for dismantling electrical part and terminals.
• 🧤 Safety glasses and thick gloves are mandatory protection of eyes from metal shavings and hands from sharp metal edges.
• 🛢️ Container for waste oil - volume of at least 1 liter, since in old compressors there can be a lot of oil.

⚠️ Attention: It is strictly forbidden to use an angle grinder (angle grinder) to cut the compressor housing! Sparks from the abrasive wheel can ignite oil vapors or freon residues, resulting in an explosion or fire. Use only the mechanical method of knocking down the seam.

Particular attention should be paid electrical safety. Before starting any work, make sure that the unit is disconnected from the network at least an hour before starting work so that the capacitors in the starting circuit have time to discharge. The residual charge can be strong enough to cause a painful electric shock, although not fatal, but unpleasant.

Removing the compressor from the refrigerator frame

The process of removing the unit from the refrigerator begins with freeing up space. You will need to move the refrigerator away from the wall and gain access to the back of it. Older models often have a heavy metal frame, so make sure that the equipment is stable and will not fall during manipulation.

The first step is to disconnect copper tubesgoing from the condenser and evaporator to the compressor. For this, side cutters or pipe cutters are used. If you plan to use the compressor in the future, try to cut the tubes as far from the body as possible, leaving the “tails” for future crimping. If the unit is being recycled, you can have a snack in any convenient place.

The compressor itself is attached to the metal frame of the refrigerator, usually with four bolts or studs that pass through the rubber shock absorbers. These shock absorbers dampen vibration when the motor is running. In Soviet refrigerators they are often made in the form of rubber bushings with metal washers. Over time, the rubber hardens and cracks, so when removing, act carefully so as not to injure yourself on the sharp edges of the burst rubber.

After unscrewing the nuts on the studs, the compressor can still hold on due to the weight and stuck connections. Gently rock the unit from side to side. If it does not budge, do not use excessive force to avoid tearing the studs away from the motor housing. It’s better to drop a little penetrating lubricant (for example, WD-40 or an analogue) on the threaded connections and wait 10-15 minutes.

Opening the sealed casing (case)

This is the most labor-intensive and critical stage of the work. The housing of the Soviet compressor consists of two hemispheres welded together at the equator. The factory welding is very reliable, and our task is to separate these halves without damaging the insides. There are two main methods: mechanical (knocking down) and drilling.

With the mechanical method, the compressor must be securely fixed. It is best to place it on a hard surface (concrete floor, workbench), placing wooden blocks underneath so as not to damage the lower part. The chisel is set with its tip exactly on the line of the weld. Hammer blows should be strong but controlled. Your goal is not to pierce the metal, but to cut down the flow of welding.

Move in a circle, making several blows at one point, then moving on to the next section. After completing a full circle, the procedure is repeated. It usually takes 3-4 circles for the seam to begin to unravel. At some point, you will hear a characteristic click and the top cover will rise.

⚠️ Attention: When the seam is knocked down, metal shavings and scale fly in different directions at high speed. Working without safety glasses at this moment is unacceptable and can lead to serious eye injury.

An alternative method is drilling rivets if the compressor model is not fastened with a continuous seam, but with spot welding or bolts (which is less common for completely sealed Soviet models, but is found in later modifications). If you see a number of points around the perimeter, you can try drilling them with a metal drill with a diameter of 6-8 mm. This is cleaner, but takes longer and requires a powerful drill.

Removing the internal filling and diagnostics

After the weld is knocked down and the top cover is removed, the internal structure electric motor and the compressor part will open before you. Immediately prepare a container for the oil. When the housing is tilted, a dark, viscous liquid will flow out of it - this is used compressor oil. Its volume can vary from 200 to 400 grams depending on the model (for example, in HKD-1.5 or FK-1.5 volumes may differ).

Inside you will see a massive stator with windings, a rotor and the piston group itself, mounted on springs or rigid suspensions. Soviet compressors often use a crank mechanism, similar to a car mechanism, but in miniature. The piston moves inside the cylinder, compressing the gas.

To remove the “internal” (motor-compressor unit), you need to disconnect the electrical wires coming from the starting relay and protective thermal contact to the engine windings. They are usually mounted on a terminal block or soldered. Carefully remember or photograph the connection diagram so that during assembly (if it is planned) you do not confuse the phase, starting and working windings.

Why is there a lot of oil inside?

The oil in the compressor serves not only as a lubricant, but also as a seal between the piston and cylinder, and also removes heat from rubbing parts. In older models, the oil level could be higher than in modern ones, which provided a margin of safety, but increased the risk of water hammer if installed incorrectly.

After disconnecting the wires, the unit can be removed from the lower bowl. Pay attention to the condition bearings and bushings. If there is wear on the shaft, and there is play in the bearings, then restoring the compressor will require replacing these parts, which is extremely difficult to do in a garage due to the lack of original spare parts.

Typical faults during disassembly

During the dismantling process, you may encounter a number of problems typical specifically for old Soviet technology. Understanding their nature will help you avoid fatal mistakes. Below is a table of the main problems and methods for solving them.

One of the common problems is water hammer. If the refrigerator stood horizontally for a long time, oil could flow into the cylinder. When starting, the piston, unable to compress the liquid, breaks the connecting rod or valve group. During disassembly, this can be seen immediately: the connecting rod will be bent or broken.

An interturn short circuit in the stator windings is also common. Visually, this manifests itself in the blackening of the varnish on the wires, the appearance of burning or the characteristic smell of scorched insulation. If the winding is burned out, then operation of such a compressor is impossible without major repairs.

Assembly and preservation after disassembly

If your goal was to recycle or use parts for other needs (for example, creating a compressor for airbrush), then reassemble in a sealed enclosure is usually not required. However, if you have carried out diagnostics and want to save the unit “just in case,” it must be mothballed.

The main enemy of a disassembled compressor is humidity. Open windings and internal cavities instantly absorb moisture from the air, which leads to corrosion and oxidation of contacts. Immediately after disassembling and drying (if you washed the parts), blow out the insides with compressed air.

For preservation, you can use special anti-corrosive sprays or simply tightly plug all the holes (suction and discharge pipes, shaft output) with rubber plugs or pieces of thick cloth soaked in oil. The top cover of the casing can be temporarily screwed on with self-tapping screws or simply covered with it over the unit, sealing the joint with tape to minimize air access.

The disassembled compressor should be stored in a dry room, in an upright position, so that residual oil does not leak out and contaminate the outer surface, creating a sticky film that will collect dust.

Frequently asked questions (FAQ)

Is it possible to restore a burnt-out Soviet compressor yourself?

Theoretically, it is possible if Only the insulation of the wires burned out, but the core was intact. However, rewinding a motor requires special knowledge, equipment and the presence of copper wire of exactly the same cross-section. In most cases, it is easier and cheaper to find a used analogue or a modern compressor of suitable power.

What kind of oil should be poured into an old compressor during maintenance?

Soviet compressors (KhKD, FK) were usually filled with HF-12-16 or HF-22-24 mineral oil. Modern synthetic oils (POE) may be incompatible with the residues of old mineral oil and insulation material, so it is better to use proven mineral analogues or special oils for retro equipment.

Why does a disassembled compressor get very hot during operation?

In normal mode, the compressor is cooled by the flow of freon passing through its housing. When operating “in air” (without a freon circuit), there is no cooling and overheating occurs very quickly. Long-term operation without load and cooling will lead to thermal breakdown of the insulation and jamming.

Where can I find a wiring diagram for an old compressor?

The diagram is often printed on a sticker that is located on the compressor itself or on the start relay cover. If the sticker is unreadable, look for the model markings (for example, PD-1, HKD-1.5) in technical reference books or on refrigeration forums. Standard circuit: working winding, starting winding and common wire.