Sooner or later, every owner of household appliances is faced with a situation where refrigeration unit stops performing its functions. A humming sound without cooling or a completely silent compressor often requires serious attention. Many craftsmen immediately suggest replacing the unit, but for diagnostics or disposal you need to know how to properly dismantle and open the old motor.
This process requires not only technical skills, but also compliance with strict safety rules. Hermetic compressor is under pressure and contains refrigerant, so you cannot simply “cut” it without preparation. In this article, we will analyze in detail the stages of disconnecting, dismantling and partially disassembling the unit to check the internal components.
It is worth immediately noting that the complete factory assembly of such motors does not imply subsequent repairs at home. However, disassembling attachments checking the electrical part allows you to accurately determine the cause of the breakdown. This knowledge will save money on diagnostics and help you understand whether restoration makes sense or a complete replacement of the unit is required.
Preparation of the workplace and necessary tools
Before starting any work with electrical appliances, it is critically important to ensure safety. You will need a free space with good lighting and ventilation. Repair area It must be protected from accidental moisture, since we will be working with electrical components and metal parts.
For successful dismantling, you will need a standard DIY kit, supplemented with specific tools. You should not try to replace specialized devices with homemade analogues, this can lead to injury or damage to components.
- 🛠️ A set of flat-head and Phillips-head screwdrivers for removing casings and terminals.
- 🔧 Pliers and side cutters for working with wires and clamps.
- ⚡ Multimeter to check the integrity of the windings and resistance.
- 🧤 Protective gloves and glasses to protect against possible sparks or sharp edges.
⚠️ Attention: Before starting work, be sure to disconnect the refrigerator from the power supply. Residual voltage in capacitors can be dangerous, so do not touch live parts with bare hands immediately after switching off.
Pay special attention to preparing a container for collecting oil. There is compressor oilin the compressor crankcase, which will leak out when the system is opened. It is toxic and requires proper disposal, so cover the floor with rags or prepare a special tray.
Removing the compressor from the refrigerator body
The first stage is removing the motor from the refrigerator shaft. In older models, such as ZIL or Biryusa, the compressor is often located in the lower rear part and is covered with a metal casing. Remove the back panel by unscrewing the fastening screws around the perimeter.
After removing the protection, you will see the unit itself mounted on the frame. It can be welded or bolted to the base. In modern and many older models it is used vibration isolation through rubber bushings, which simplifies removal. If the legs are welded, they will have to be carefully cut off with a grinder, being careful.
It is important not to damage the copper tubes of the condenser and evaporator if you plan to continue using the refrigerator or scrap it as a whole. Refrigerant The system is under pressure, and a sudden rupture of the tubes can lead to oil splashing.
Disconnect the electrical wires going to the start relay. They are usually secured with plastic clips or clamps. Carefully bend them back and remove the connectors. If the wires have become stuck or oxidized, it is better to cut them with side cutters, leaving a reserve for the possible connection of a new motor.
Removing the starting relay and protective thermal contact
At the end of the compressor there is a black plastic casing, inside of which the key starting elements are hidden. This starting relay is also a thermal release. Removing them does not require the use of brute force; just carefully pry the case with a screwdriver or squeeze the fixing tabs.
Inside you will find two main components. The first is a start relay, which can be in the form of an induction coil or a posistor (in newer models). The second element is a bimetallic plate thermal relaythat protects the motor from overheating. They are put directly on the contact pins of the compressor.
- 🔌 Take a photo of the connection diagram before removal so as not to confuse the polarity during assembly.
- 🧹 Clean the contacts from carbon deposits and oxides with fine emery cloth paper.
- 👀 Visually inspect the relay coil for blackening or melting of the insulation.
Often the cause of the malfunction lies precisely in sticking relay contacts or breakdown of the posistor. If, when shaking the relay, a knock is heard inside (the core has broken off), then the element requires replacement. You can check it with a multimeter in continuity mode.
How to check a posistor with a multimeter?
Set the device in resistance measurement mode. At room temperature, a working posistor should show low resistance (several tens of ohms). If the resistance is infinitely large or close to zero, the part is faulty. When heated, the resistance should increase sharply.
After removing the relay, access to three contact pins coming out of the hermetic zone will open. They are arranged in a triangle. Between two of them (working and starting windings) there should be resistance when dialing, and the third (common) should ring with each of them. The absence of a bell indicates winding breakage inside the motor.
Checking the electrical serviceability of the windings
Before proceeding with the physical opening of the housing, it is necessary to accurately diagnose the electrical part. This will avoid unnecessary disassembly if the motor burns out completely. Use a multimeter to measure the resistance between the contacts.
Normal resistance values depend on the power of the motor, but usually range from 10 to 35 Ohms for the working winding and slightly higher for the starting winding. If the device shows one (infinity), then a break has occurred. If zero, there is a short circuit.
It is also important to check the breakdown on the housing. Press one multimeter probe to the cleaned area on the compressor body (where there is no paint), and touch each of the three contacts with the other. Insulation resistance should be infinite. Any readings indicate a breakdown, which makes operation dangerous.
| Measurement type | Normal reading | Failure sign |
|---|---|---|
| Working winding | 10 - 25 Ohm | Open or short circuit |
| Start winding | 20 - 40 Ohm | Open or short circuit |
| Breakdown to the body | Infinity (∞) | Any numerical value |
⚠️ Attention: If a breakdown to the body is detected, further operation of the refrigerator is prohibited. This creates a direct threat of electric shock when touching the metal parts of the refrigerator body.
Opening the sealed casing (Hermozone)
The most difficult and dangerous part of the process is opening the steel case, which contains electric motor the piston group. Factory welding is performed in a circle butt-end. To disassemble at home, you will need a grinder with a thin metal disc or a hacksaw.
Do not try to break the housing with a hammer or chisel - this may damage the internal motor mount or deform the stator. Carefully cut along the entire circumference of the weld. Wear safety glasses, as metal shavings fly in all directions.
☑️ Safely opening the casing
After the cut, the top cover will be removed. Inside you will see the motor itself, immersed in oil, and a system of tubes. There may be residual freon pressure inside the casing, so make the first cut carefully, pointing the tool away from you.
Pay attention to the condition of the oil. If it is black, cloudy or has a burning smell, it means that processes of insulation destruction or overheating have occurred inside. Clean oil should be transparent or slightly yellowish, without foreign inclusions.
Diagnostics of the mechanical part and suspension
After removing the cover, access to the mechanics opens. The motor is suspended on three springs that dampen vibrations. In old refrigerators, these springs can be stretched or burst, which causes loud noise and beating during operation. Internal suspension requires visual inspection for integrity.
The central element is the rotor and stator. If the engine hummed but did not start, the piston group may be jammed. Check the free play of the shaft. If the shaft does not turn by hand (with the power turned off), it means that the cylinder is scuffed or the plain bearings have collapsed.
- 🔍 Inspect the valves for cracks or carbon deposits.
- 🤲 Check the play of the connecting rod by rocking it to the sides.
- 💧 Assess the oil level, it should cover the lower part of the motor housing.
Often in old compressors, the crank pin or the connecting rod itself wears out. This leads to knocking and the inability to create the necessary pressure. Repairing such units at home is practically impossible due to the lack of spare parts and the need for precise adjustment of the gaps.
Disposal and safety precautions during disassembly
A disassembled compressor is a source of danger. There may be residual refrigerant inside, which forms toxic compounds when burned. In addition, the motor windings contain valuable copper, and the body is steel, so proper waste sorting is important for the environment.
Oil from the compressor should not be poured into the sewer or onto the ground. Collect it in a sealed container and take it to a collection point for waste petroleum products. Even a small amount of oil can contaminate a significant volume of water.
⚠️ Attention: It is strictly prohibited to burn insulation from windings to extract copper. When varnish and refrigerant burn, dioxins and other toxic substances that are hazardous to health are released.
If your goal is simply to recycle an old refrigerator, it is better to hand it over entirely to a specialized organization. They have licenses to work with freon and correctly dispose of all components, including heavy metals and chemical compounds.
Frequently asked questions (FAQ)
Is it possible to replace the compressor in an old refrigerator with a new one?
Theoretically it is possible, but this requires professional equipment. It is necessary to evacuate the system, fill the exact amount of freon and oil, and also solder the tubes. It is impossible to do this efficiently at home without a vacuum pump and scales.
Why does the compressor hum but does not start?
Most often the reason is a faulty start relay or a jammed piston group. A break in the starting winding is also possible. Diagnostics with a multimeter and checking the mechanical rotation of the shaft are required.
How much oil should be in the refrigerator compressor?
The exact volume depends on the model, usually from 150 to 300 grams. Overfilling the oil will lead to deterioration of heat transfer and water hammer, and underfilling will lead to overheating and jamming. The level is checked using factory marks or passport data.
Is it dangerous to open the compressor yourself?
Yes, it is dangerous. There may be residual pressure inside, and refrigerant vapor displaces oxygen. In addition, there is a risk of injury from the sharp edges of the metal or getting an electric shock if the windings are not checked correctly.