Dismantling the compressor is one of the most technically complex and important operations when repairing household air conditioning equipment. Refrigeration unit is a sealed system under high pressure, which requires from the master not only mechanical precision, but also strict adherence to safety rules. Improper handling of the unit can lead to injury, damage to the windings or depressurization of the circuit, which will make further operation impossible.
Before proceeding with the physical removal of the casing and internal components, it is necessary to clearly understand the design of the device. Hermetic compressor usually consists of an electric motor and a piston group, enclosed in a steel case. Most household models use asynchronous motors with a starting winding that operate in an oil environment. It is this environment that provides lubrication of rubbing parts and heat removal, so any manipulation requires preliminary preparation of the workplace and tools.
It is important to realize that there is always residual pressure of refrigerant and oil vapor inside the compressor housingeven if the system is visually empty. Abrupt opening or damage to pipelines without prior bleeding can lead to the release of aggressive substances. A professional approach begins long before the moment the wrench touches the first bolt, and includes diagnostics, tool preparation and risk assessment.
Required tools and safety measures
Quality repairs impossible without a specialized set of tools adapted for working with metal and electrical components. The basic list includes pliers, a set of screwdrivers with different slotted profiles, as well as specific tools for working with copper pipes. Particular attention should be paid to the insulation of the handles, since work is often carried out in conditions of possible humidity or the presence of conductive liquids.
Electrical safety comes first, since start relay and the motor windings are under voltage of 220 volts. Before starting any work, you must completely de-energize the device by unplugging the plug from the socket. It is not enough to simply turn off the refrigerator with a button or thermostat - a physical break in the circuit with the electrical network is required. Ignoring this rule may result in electric shock, especially if the insulation of the wires inside the casing is broken.
⚠️ Attention: It is strictly forbidden to open the sealed compressor housing with a grinder or a hacksaw without first removing the refrigerant. Residual pressure in the system can disperse metal shavings and fragments at high speed, which is dangerous for eyes and skin.
To work with copper lines, you will need a pipe cutter, rolling and torch if further soldering is planned. However, if the goal is solely to disassemble the motor for troubleshooting, it is enough to have a hammer, a center punch and powerful wire cutters on hand. It would be a good idea to prepare a container for draining technical oil, which may be contaminated with insulation decomposition products or acids.
☑️ Preparation of the workplace
Removing the compressor from the refrigerator body
The first step is to remove the unit itself from the niche of the refrigerator. Typically compressor located at the lower rear of the device and secured to the frame using four shock-absorbing bushings. These bushings are made of rubber and metal, and over time they can become stiff or stick, which requires careful handling when removing.
The process begins with disconnecting the electrical contacts. It is necessary to remove the protective cover of the starting relay and carefully disconnect the wires, having previously photographed the connection diagram. Often the contacts oxidize, so they should be cleaned, but this must be done carefully so as not to damage the terminals. After disconnecting the wires, access to the copper tubes coming from the condenser and evaporator is freed.
- 🔧 Bite off the copper tubes at a distance of 10-15 cm from the compressor body to leave a technological reserve for future rolling.
- 🔌 Carefully remove the starting relay and thermal protection, checking them for the absence of visible damage and carbon deposits.
- 🛢️ Prepare a container for oil, since when the compressor is tilted, residual lubricant may leak out of the cut tubes.
- 🔩 Loosen the mounting bolts on the frame, holding the motor so that it does not fall sharply after removing the last one latch.
Removal from the frame requires the application of physical force directed upward and slightly to the side. Rubber shock absorbers can resist, so you can use a flat-head screwdriver as a lever, but you need to rely on the metal part of the frame, and not on the motor itself. After removing the unit, it should be placed on a flat, stable surface covered with rags for further disassembly.
Opening the sealed compressor casing
The most difficult part of the process is removing the top cover of the metal casing, which is welded around the perimeter. The factory welding is done very well, so you can’t just open the lid. There are two main methods: mechanical sawing of the seam and knocking out the lid using punching. The choice of method depends on the availability of tools and the experience of the master.
When using a grinder or a hacksaw for metal, it is necessary to make a circular cut strictly along the line of the factory seam. Sealed casing has double walls at the welding site, so it is important not to damage the internal windings and stator. The cutting depth must be constantly monitored, taking short breaks to cool the metal so as not to overheat the insulation of the wires inside.
⚠️ Attention: When using a power tool to cut the casing, be sure to use safety glasses. Metal dust and sparks may get into the eyes or ignite oil vapors if present on the surface.
An alternative method is to score the seam in a circle using a hammer and chisel or punch. A deep groove is made around the entire perimeter, after which the lid is cut off with several precise blows. This method is less productive, but safer for the internal filling, as it eliminates the risk of the disk accidentally touching the windings. After removing the cover, access to the internal device opens.
What is inside the casing?
Inside there is an electric motor mounted on springs, immersed in oil. There is also a system of suction and discharge valves, as well as a filter drier, which is often attached to the housing.
Diagnostics and disassembly of the electric motor
The internal electric motor is an asynchronous machine with a squirrel-cage rotor. The stator is fixed inside the casing on three springs, which compensate for vibrations during operation. To remove the rotor and stator, it is necessary to disconnect the suction and discharge tubes from the inside of the housing, and also remove the filter drier.
The key element of diagnosis is checking the windings. Starting and working windings they must have a certain resistance, which is measured with a multimeter. If the resistance approaches zero, there is a short circuit, and if it approaches infinity, there is an open circuit. It is also important to check the resistance between the windings and the motor housing - it should be maximum, which indicates the integrity of the insulation.
Disassembling the stator and rotor itself at home is practically not done, as it requires hydraulic presses and special pullers. Usually, it is enough for a technician to remove the rotor for a visual inspection for scoring or signs of overheating. If traces of friction against the stator are visible on the rotor plates, the entire engine must be replaced, since the balancing is imbalanced.
The valve group located at the end of the cylinder deserves special attention. This is where malfunctions most often occur, leading to loss of productivity. Thin reed valves can break or become deformed, compromising the seal of the compression chambers. Their replacement is possible, but requires high precision and cleanliness.
Typical malfunctions and their symptoms
Understanding the symptoms allows you to quickly determine the cause of the breakdown before starting a deep disassembly. Interturn closure Often it manifests itself in the fact that the compressor hums, but does not start, or starts for a few seconds and knocks out the circuit breaker. In this case, the thermal relay heats up and breaks the circuit, saving the windings from final combustion.
Mechanical wear of the piston group leads to the fact that the motor runs constantly without turning off, but the cold does not accumulate in the chamber. The pressure in the system does not rise to the required values. In such cases, a metallic knock or clanging sound is often heard inside the casing, indicating destruction of the connecting rod or piston pins.
| Malfunction | Symptom | Cause | Solution |
|---|---|---|---|
| Winding break | The motor does not hum, does not start | Overheating, power surge | Replacing the compressor |
| Stucking | Humming, relay clicks | Lack of oil, wear | Attempt to wedge or replacement |
| Valve wear | Works without shutting down | Natural wear, dirt | Replacing the valve group |
| Breakage to the housing | Knocks out the RCD/automatic device | Destruction of insulation | Replacing the compressor |
Another common problem is loss of power due to coking of the oil channels or thickening of the oil. This is common in older models, especially if the refrigerator has been idle for a long time. In such cases, a complete oil change and flushing the system can temporarily extend the life of the unit, but this is rather a temporary measure.
Assembly and inspection after repair
Assembly is carried out in the reverse order of disassembly, but taking into account critical nuances. The motor mount springs must be installed correctly so that the rotor does not touch the stator. Any shift in the center of gravity will result in strong vibration and noise during operation. The fastening bolts of the casing cover are not used - instead, the housing is welded or sealed.
Before final sealing, it is necessary to flush the system with nitrogen to remove moisture and chips. Evacuation - a mandatory step that allows you to remove air and water vapor from the circuit. Without creating a deep vacuum, the remaining moisture will freeze in the capillary tube, blocking the circulation of the refrigerant.
After sealing the casing and charging with refrigerant, a test run is carried out. It is necessary to control the current consumption of the windings using current clamps. If the current is within the rated values, and heating is observed at the output of the capacitor, it means motor-compressor it is functioning normally. The absence of vibrations and extraneous sounds is also checked.
⚠️ Attention: Technical characteristics of compressors from different manufacturers may vary. Always check the parameters (power, refrigerant, oil type) with the markings on the nameplate of the specific device before assembly.
High-quality repairs can extend the life of the refrigerator by several years. However, it is worth remembering that an opened and re-welded compressor no longer has factory tightness and reliability. Therefore, such work should be performed only by qualified specialists using professional equipment.
Is it possible to change the oil in a compressor without opening it?
Theoretically, you can try to pump out the old oil through the process pipe and fill in new one, but the effectiveness of such a procedure is extremely low. A significant amount of old lubricant remains inside the engine and on the walls, which mixes with the new one, worsening its properties. A full replacement is only possible with complete disassembly and washing with gasoline or a special solvent.
Why does the compressor hum but does not start?
The most likely reason is a faulty start relay or jammed piston group. An interturn short circuit in the starting winding is also possible. In some cases, installing a more powerful capacitor or starting device helps, but this is a temporary solution before replacing the unit.
Is it dangerous to open the compressor yourself?
Yes, it is dangerous. In addition to the risk of electrical shock and injury from the tool, there is the danger of flying metal fragments under pressure. In addition, refrigerant vapor can be toxic or flammable when mixed with air. Without skills and tools, it is better not to take risks.
What oil to use for replacement?
The type of oil depends on the type of refrigerant. For R12 and R134a freons, mineral or polyol ether (POE) oil is used. Freon R600a (isobutane), which is explosive, requires special synthetic oils. Mixing different types of oils is strictly prohibited, as this will lead to the formation of sediment and acids.