When we hear a characteristic hum in the kitchen coming from behind the wall, few people think about the complex mechanism that makes it. It compressor is the heart of any refrigeration system, forcing the refrigerant to circulate through the tubes and remove heat from the chambers. Without this unit, creating and maintaining low temperatures would be impossible, and the products would spoil in a matter of hours.
Externally, this device resembles a sealed black cylinder or barrel located in the lower rear part of the unit. Many owners of household appliances only see it during general cleaning or when trying to repair it themselves when the refrigerator stops freezing. Understanding how the compressor workshelps to quickly diagnose the problem and avoid unnecessary expenses on calling a technician for simple operations.
In this article we will analyze in detail the internal structure of the motor, consider its types and learn to distinguish normal operation from the harbingers of a breakdown. You will find out why some models are quieter, while others consume less energy, and what to look for when choosing new equipment.
The principle of operation and main functions of the compressor
The main task of this unit is to compress and move refrigerant vapor through a closed circuit of the system. Compressor sucks freon gas from evaporator, compresses it to high pressure and temperature, and then pushes it into the condenser. There the gas cools down, turns into liquid and returns to the evaporator, where it boils and takes away heat.
This process is cyclical and continuous, unless we are talking about modern inverter models. In classic refrigerators, the motor runs jerkily: it turns on, reaches the set temperature, then turns off. It is at the moments of start and stop that the main wear of the mechanical parts occurs and the characteristic click of the relay is heard.
⚠️ Attention: If you plan to inspect the compressor, be sure to disconnect the refrigerator from the power supply. Residual charges may remain on the housing, and touching hot tubes immediately after use can cause burns.
In addition, the device provides the necessary pressure for effective heat transfer. Without creating a pressure difference, the refrigerant would simply stand in the tubes without changing its state of aggregation. Efficiency The entire system directly depends on the performance of the motor and the tightness of its housing.
Internal structure: what's inside the black tank
Visually we We see only a metal casing, but a complex mechanism is hidden inside. Most household refrigerators are equipped piston with hermetic compressors. This means that the casing is welded at the factory and is not intended for opening at home.
Inside the casing there is an electric motor and the compressor unit itself, mounted on springs. Springs are necessary to dampen vibrations, since during operation the piston moves at high speed. If one of the springs bursts, you will hear a strong metallic clanging and knocking sound when starting.
The main elements of the internal design include:
- 🔩 Cylinder and piston - the main unit where the gas is compressed.
- ⚡ Electric motor - sets in motion crankshaft.
- 🛢️ Oil system —provides lubrication of rubbing parts and is partially involved in cooling.
- 🔌 Start relay —often mounted externally, but electrically connected to the motor windings.
Lubrication in the system is carried out by splashing: the ends of the shaft are immersed in oil located at the bottom of the housing, and during rotation they scatter it among the units. This is why horizontal transportation refrigerators are undesirable - oil can flow into the freon circulation circuit, which will lead to clogging of the capillary tube.
Why can’t you open the compressor?
There may be excess oil inside the housing pressure, as well as oil and refrigerant vapors. Opening it yourself is dangerous to health and makes further repair of the unit impossible - only replacement entirely.
Varieties of compressors: from classic to inverter
Technology does not stand still, and today you can find several types of engines on the market. Understanding their differences will help you choose equipment that will be comfortable for you.
The most common type is linear (standard) compressor. It works on the "on-off" principle. When the temperature in the chamber rises above the set point, the relay closes the circuit, the motor starts at full power and runs until the thermostat registers cooling. Then there is a pause.
More modern inverter models do not have sharp starts. The motor turns on once when you first start the refrigerator, and then simply changes the speed of rotation of the shaft, maintaining the temperature. This allows you to save energy and reduce noise levels.
Comparative table of characteristics of various types of compressors:
| Characteristics | Conventional (Linear) | Inverter | Linear-inverter |
|---|---|---|---|
| Operating principle | Cyclic (start-stop) | Smooth power change | Smooth movement piston |
| Noise level | Medium / High | Low | Very low |
| Energy consumption | Standard | Economical (up to -30%) | Maximum economical |
| Service life | 5-10 years | 10+ years | 10+ years |
There are also two-compressor systems, where one motor is responsible for the refrigeration chamber, and the second for the freezer. This allows you to independently regulate the temperature and turn off one of the chambers without affecting the operation of the other.
How to determine a malfunction by external signs
Diagnostics of a compressor often begins with a visual inspection and listening. If the refrigerator has stopped freezing, but the light is on inside, the problem most likely lies in the motor or its starting system.
The first thing you need to pay attention to is case temperature. When in operation, the compressor heats up, but it should not be so hot that it cannot be touched. Excessive heating may indicate an interturn short circuit of the windings or problems with freon circulation.
Alarm signals requiring intervention:
- 🔊 Loud knocking or clanging at startup - a sign of mechanical destruction of components inside the casing.
- 🔥 The protective relay clicks every few seconds, but the engine does not start - the piston group may be jammed.
- ❄️ The refrigerator runs non-stop, but the temperature does not drop - the compressor does not create the required pressure (wear of the rings piston).
⚠️ Attention: If you smell a burning smell or see sparking in the compressor area, immediately unplug the cord from the outlet. Operating such a device can lead to a fire.
Sometimes the motor hums, but does not start. This may be due to a voltage drop in the network or a faulty start relay. In such cases, an attempt to turn it on repeatedly may completely “kill” the motor windings.
Instructions for initial diagnostics with your own hands
Before calling a technician, you can carry out a number of simple checks that will help you understand the scale of the problem. To do this, you will need a minimum set of tools and compliance with safety precautions.
Start by checking the voltage in the outlet. If it is significantly below 220 volts, the compressor may simply not start due to lack of power. In this case, a stabilizer will help.
Algorithm of actions for checking:
- 🔌 Disconnect the refrigerator from the mains and remove the back plastic panel.
- 👀 Inspect the wires for melting, and the compressor itself for traces of oil (this is a sign depressurization).
- 🔋 Test the windings with a multimeter (skill in operating the device is required).
- 👂 When you turn it on, listen: there should be a click of the relay and a hum of the motor.
☑️ Checklist for initial testing
If the relay makes a rattle sound when removed and shaken, it means that the contact inside has burnt out or the “tablet” has broken. Replacing the relay is an inexpensive procedure and often solves the problem of non-starting.
Normal winding resistance (approximate):Starting: 20-40 Ohm
Operating: 10-15 Ohm
Between the housing and the windings: Infinity (no breakdown)
A specialist with a vacuum pump and a filling station is required.
Service life and factors shortening the life of the motor
The average service life of a modern compressor is from 10 to 15 years. However, the actual figure greatly depends on operating conditions. Manufacturers provide a certain margin of safety, but it is not unlimited.
One of the main enemies is overheating. If the refrigerator is located close to the wall, in a niche without ventilation, or next to a radiator, heat transfer deteriorates. The engine operates with overload, the oil loses its properties, which leads to accelerated wear.
Other risk factors:
- 🌡️ Frequent defrosting —sudden temperature changes are destructive to the system.
- 🚚 Improper transportation — impacts and tilts of more than 40 degrees can damage the suspension springs.
- ⚡ Power surges —require the installation of a protective voltage relay.
⚠️ Attention: Technical characteristics and installation requirements may vary depending on models. Always check the official instructions of the manufacturer of your refrigerator before installing it in a niche.
Installing the refrigerator in an unheated room in winter also has a negative effect. The oil in the compressor thickens, and when starting, the engine runs “dry,” which quickly leads to jamming.
Replace or repair: economic aspect
When diagnostics have confirmed the death of the compressor, the question arises about the feasibility of repair. Replacing a motor is a complex process that requires soldering copper tubes, evacuating the system and refilling freon.
The cost of a new compressor, including the work of a technician, is often 50-70% of the price of a new refrigerator. If your unit is more than 7-10 years old, it is often more profitable to buy new equipment than to reanimate the old one.
However, there are exceptions. If you have a premium model or a refrigerator built into your kitchen unit, a replacement may be worth it. In the case of ordinary "Atlantas" or "Indesites" 15+ years old, repairs are not economically feasible.
How much does it cost to replace a compressor on average?
The price consists of the cost of the unit itself (from 3,000 to 15,000 rubles) and the cost of work (from 2,000 to 5,000 rubles). Inverter models are much more expensive than linear ones.
Is it possible to install a compressor of a different capacity?
It is strictly not recommended. The power must correspond to the volume of the chambers and the type of refrigerant. Incorrect selection will either lead to underfreezing or constant overheating and breakdown.
Why is a new refrigerator louder than the old one?
Modern requirements for environmental friendliness dictate the use of new types of refrigerants and oils, which can be noisier. In addition, thin case walls insulate sound worse.
Is humming after switching off normal?
Yes, this is normal. After stopping the engine, the pressure in the system equalizes, the liquid flows, and gurgling or humming may be heard for 1-3 minutes.
Does the color of the compressor affect its quality?
No, black color is a standard powder coating for corrosion protection and better heat dissipation. Color is not a marker of manufacturer or quality.