Dismantling and Subsequent disassembly sealed units often become a necessity when valuable non-ferrous metal needs to be recovered, equipment must be disposed of, or, in rare cases, internal components need to be replaced for pilot plants. Standard compressor is a sealed steel sphere or cylinder, inside which the motor windings and piston group are under pressure, immersed in oil. You can’t just open it like a regular household appliance - factory sealing is done using argon welding or hard soldering, which requires the use of special tools.
Before you begin to physically impact the case, you must clearly understand the risks: inside Residual refrigerant pressure may remain, and the opening process itself is associated with the formation of sparks and metal shavings. If your goal is repair household appliances, then in 99% of cases there is no point in opening the casing - it is cheaper and more reliable to replace the unit with a new or used one. However, for craftsmen involved in converting compressors into vacuum pumps or aerators, understanding the internal structure is a critical skill.
In this article we will take a detailed look at the technology for safely opening the housing, methods for separating the motor group and precautions when working with residual freon and technical oil. You will need not only physical strength, but also an understanding of the principles of operation electric motorso as not to damage the windings when removing the rotor. Remember that after opening, the factory seal will be lost forever, and it will no longer be possible to assemble the unit back to work with refrigerant without sophisticated industrial equipment.
Preparation of the workplace and the necessary tools
Organizing a workspace is the first step to successful dismantling, which cannot be ignored. You will need a sturdy workbench or metal table that can withstand hammer blows and the weight of a cast iron or steel frame. Since the opening process is often accompanied by the leakage of black technical oil and possible splashing of chips, the surface should be covered with a thick film or a sheet of plywood that you do not mind spoiling. The lighting should be bright and directional so that you can distinguish the line of the factory seam, which is often hidden under a layer of paint or rust.
The basic set of tools for opening includes an angle grinder (grinder) with thin cutting discs for metal, a powerful hacksaw for metal with a new blade and a set spanners. To work with the electrical part, you will need a multimeter, screwdrivers with insulated handles and side cutters. If you plan to use the compressor as a vacuum pump, you will also need skins to clean the contacts and, possibly, new bearings if the old ones have play.
☑️ Preparation for disassembly
Pay special attention to personal protective equipment. Metal dust generated during sawing should not get into the eyes or respiratory tract, so a respirator and goggles are required. Also have a rag and solvent on hand to degrease surfaces, as the outer walls of the unit are often covered with a layer of sticky dirt and oxides. A properly prepared place will save you time and nerves during the work process.
Safety precautions and precautions
⚠️ Attention: Before starting any work on cutting the body, make sure that the process pipes (copper tubes) are not pinched or bent if you plan to reuse them. Sharp pressure on copper can lead to its flattening.
The main danger when disassembling old refrigeration equipment lies in the refrigerant residues. Even if the device has stood idle for ten years, pressure of several atmospheres may remain in the system. When the case is heated by an angle grinder or when the seal is suddenly broken, a pop or release of gases is possible. Although modern freons are not toxic in small doses, they displace oxygen, and when mixed with oil at high temperatures they can form toxic compounds. Therefore, all work should be carried out in a well-ventilated area or in the open air.
The second aspect of safety is electrical. Before removing the terminal box cover and disconnecting the wires, the device must be physically disconnected from the network. The capacitor, if present in the circuit (although older models may not), is capable of storing charge. Check that there is no voltage on the contacts using multimeter or an indicator screwdriver. It is also important to securely fix the compressor itself: when working with an angle grinder, vibration can dislodge the light unit, which will lead to hand injury or breakage of the disk.
Danger of old models
In very old refrigerators (manufactured before the 90s), it could be used as a refrigerant ammonia or propane-butane mixtures. Ammonia is toxic and has a strong odor, and hydrocarbons are explosive. If upon opening you notice a strong smell of ammonia, stop work immediately and ventilate the room.
Do not forget about the temperature conditions of the tools. Cutting discs tend to overheat and burst under lateral loads. Do not put too much pressure on the grinder; let it work with its own weight. If you use a hacksaw, be careful about the tension of the blade - a file that breaks in your hands can seriously injure your palm. Following these simple rules will allow you to avoid trouble and complete disassembly without loss.
Draining technical oil and dismantling attachments
The first step is to remove attachments that interfere with access to the main body. Remove the start relay and thermal protection housing, usually secured with latches or screws. Disconnect the wires, having previously photographed the connection diagram, so that if you reassemble it, you do not mix up the phasing. At the same stage, you can remove the condenser, if it is placed separately, and unscrew the transport washers on the legs, if they are still there.
Next, you need to drain the used compressor oil. To do this, turn the unit upside down or on its side, replacing the container. A black viscous liquid will flow from the lower tube (usually a suction or discharge, depending on the model). Take your time, let the oil drain completely - this may take from 15 to 30 minutes. To speed up the process, you can blow the system with compressed air through one of the tubes, after plugging the others, but be prepared for the residue to splash.
| Compressor type | Oil volume (approximately) | Oil type | Features plum |
|---|---|---|---|
| Piston (Atlant) | 300-400 ml | Mineral | Thick, requires heating for complete drainage |
| Piston (Donbass) | 350-450 ml | Mineral | Often contains a lot of suspended metal |
| Rotary (rarely) | 200-300 ml | Synthetics | Liquid, drains quickly |
| Linear (inverter) | 250-350 ml | POE/PAG | Hygroscopic, requires quick disposal |
After draining the oil, inspect the insides through the pipes using a flashlight. If large fragments of metal or plastic dust are visible inside, this indicates a serious breakdown of the mechanical part - scuffing of the cylinders or destruction of the bearings. In such cases, further disassembly makes sense only to study the causes of failure or disposal. Clean oil (light yellow or transparent) indicates that the mechanics were in order, and the cause of the malfunction most likely lay in an electrician or a freon leak.
Technology for opening a sealed casing
The most crucial moment is the violation of the integrity of the casing. There are two main methods: careful cutting along the seam and the barbaric method of destroying the upper part. To maintain maximum utility of the unit (for example, if you are making a compressor for aeration), the first option is recommended. Find the circular seam connecting the top and bottom hemispheres. It may be hidden under paint, so clean the perimeter thoroughly.
Using a grinder with a thin disk (1 mm), make a notch along the entire perimeter of the seam. Do not try to cut through the metal right away - it is better to go through the circle 2-3 times, going deeper gradually. This will prevent the disk from jamming and reduce the risk of sparks damaging the internal windings. If you don’t have a grinder, you can use a hacksaw for metal, making several deep cuts in a circle, and then carefully knock out the jumpers with a chisel.
⚠️ Attention: It is strictly forbidden to hit the case with a hammer in the area of electrical terminals and copper tubes. Mechanical deformation can lead to short circuit of the windings or destruction of the pipes, which will make the unit unsuitable even for use as a pump.
When the seam is cut deep enough, insert a flat-head screwdriver or chisel into the cut and open the “can” with light blows of a hammer. The top cover should come off. In some models (for example, Atlant or Donbass), the lid may be held tightly and will have to be pryed off in several places. Try not to damage the internal partitions that direct the flow of oil for lubrication.
Removing the motor group and piston unit
After removing the cover, the internal structure will appear to your eyes: stator with windings, rotor (armature), shaft with eccentric and cylindrical block. The motor group is attached to the inside of the casing using three shock absorber springs. To remove the “filling”, you must first disconnect the wires from the windings (if they are not burned out or unsoldered themselves) and remove the springs. This is done with long-nose pliers or pliers; sometimes force is required.
Remove the block carefully, holding it by the lower part (crankcase). The rotor is inserted into the stator with minimal clearance, and misalignment can lead to scoring. Some designs have the shaft passing through a bearing in the bottom cap, so the shaft may need to be gently driven down or up, depending on the design. If the compressor is equipped with a lubrication system through the crankshaft, you will see channels inside the shaft that will need to be cleaned during disassembly.
The piston group in household compressors is most often made in the form of a crank mechanism. The piston can be aluminum or steel, sometimes with a graphite coating. The connecting rod is attached to the crankshaft through a plain bearing or needle bearing. When disassembling this unit, remember the orientation of the parts: the connecting rod and piston have a top and a bottom, and you cannot confuse them during assembly. Usually there is a marking or arrow on the piston indicating the direction of movement.
Defection of parts and fault analysis
Disassembled parts must be thoroughly washed in gasoline or solvent and inspect. First of all, check the stator windings for blackening or a characteristic burning smell - these are signs of an interturn short circuit. If the varnish on the wires has darkened and become brittle, such a motor will not last long. The copper should be shiny, without signs of overheating.
The cylinder and piston are a high-pressure zone. Inspect the cylinder mirror: there should be no deep burrs, marks or wear on it. Light risks are acceptable, but deep furrows will lead to decreased performance and overheating. The piston rings (if they are present in this model) should fit snugly against the walls and have a small thermal gap at the joint. Wear of the rings is the most common reason that refrigerator stops freezing, although the compressor is humming.
The compressor shaft must be perfectly straight. Place it on a flat surface and twist it - there should be no beating. Bearings (upper and lower) should not have any play. If the shaft dangles in the seats, the compressor will make a lot of noise and vibrations will quickly destroy other components. The valve plate (petals) must be smooth, without cracks or carbon deposits. Curvature of the petals breaks the tightness of the compression chambers.
⚠️ Attention: If you find copper shavings ("spangles") in the oil, this means destruction of the sliding bearings or friction of the shaft against the bushings. Operating such a unit even as a pump is not recommended, since the abrasive will quickly kill the new seals.
FAQ: Frequently Asked Questions
Is it possible to assemble the compressor back and solder it to work with freon?
Theoretically it is possible, but in practice it is extremely difficult and economically unfeasible. You will need professional equipment for vacuuming, freon charging and argon welding. In addition, it is almost impossible to find original gaskets and restore rotor balancing at home. To repair a refrigerator, it is always cheaper to buy a new sealed unit.
How much does copper weigh in one compressor?
The weight of copper depends on the power and year of manufacture. On average, from one compressor you can get from 100 to 300 grams of pure copper (stator and rotor windings, tubes). The main weight is steel (body) and cast iron (base). It is often more profitable to hand over the entire compressor for scrap ferrous metals than to waste time on extracting a small amount of non-ferrous metal.
Why does the compressor hum, but does not start after disassembly and reassembly?
The most likely reasons: incorrect assembly of the start relay, the winding wires are mixed up (start-up/operation), jamming piston group due to misalignment during assembly or lack of oil. It is also possible that during disassembly the bimetallic thermal protection element was damaged or the starting winding burned out due to a short circuit.
Where can I get oil for the compressor after flushing?
For household refrigeration compressors, special refrigeration oil is used (for example, Freol, HF 12-16 or imported analogues like Suniso). Regular motor oil cannot be used - it does not have the necessary chemical resistance to freon and can foam, which will lead to water hammer. For compressors converted for pumping air, regular compressor oil KS-19 is suitable.