The refrigerator is an integral part of the modern kitchen, ensuring the safety of food for a long time. However, few people think about what is happening inside the case when a characteristic hum is heard. It is at this moment that the compressor heart of the entire cooling system comes into operation, causing the refrigerant to circulate throughout the circuit.
Understanding the basic principles of operation of this unit will help you better navigate the operation of equipment and notice the first signs of a malfunction in time. After all, it depends on the stability of the motor operation whether your Indesit or Bosch will delight you with coolness or require expensive repairs.
In this article we will analyze in detail the internal structure of the compressor, consider the differences between linear and inverter models, and also discuss typical reasons for equipment failure.
Principle of operation of a refrigeration compressor
The main task of the compressor is to create a pressure difference in the cooling system, which allows the refrigerant to effectively remove heat from the refrigerator chambers and release it to the environment through the condenser. The process begins with the absorption of vaporous freon of low pressure and temperature, which comes from the evaporator.
Inside the sealed housing, the gas is compressed, as a result of which its temperature and pressure increase sharply. The hot, high-pressure steam is then forced into a condenser, usually located on the rear wall of the unit. Here the substance cools down and turns into a liquid state, preparing to enter the evaporator again to repeat the cycle.
A critically important point is the tightness of the circuit: even a microscopic leak of freon upsets the pressure balance, making the compressor work ineffective or completely stopping cooling. The engine operates cyclically, turning on according to a signal from the thermostat when the temperature in the chamber rises above the set value.
Modern models are equipped with protection systems that turn off the motor when overheating or power surges. This prevents windings from burning out and expensive components from failing. Understanding this cycle helps you understand why the refrigerator should not stand close to the wall - it needs heat removal to operate effectively.
Internal structure and main components
Structurally, the compressor is an electromechanical unit enclosed in a sealed steel casing. Inside this casing are the electric motor and the compressor mechanism itself, which often have a common shaft. All these elements are immersed in a special refrigeration oil, which provides lubrication of the rubbing parts.
The electrical part consists of a stator and a rotor. When voltage is applied to the windings, a magnetic field is generated, causing the rotor to rotate. A crank mechanism is attached to the shaft, which converts the rotational movement into the translational movement of the piston.
In the upper part of the housing there are three technological pipes: suction, discharge and filling. The gas enters through the suction tube and goes into the condenser through the discharge tube. The filling pipe is used only once during production or repair to fill the system with freon.
Also an important element is the start-up relay. It is responsible for supplying voltage to the starting winding at the moment of start and turns it off when the rotor reaches the required speed. If the relay is faulty, the engine may hum but not start.
- 🔩 The sealed casing protects the mechanisms from dust and moisture, and also keeps the oil inside.
- ⚙️ The crank mechanism ensures the movement of the piston, creating the necessary pressure.
- 🌡️ The thermal relay controls the engine temperature, opening the circuit in case of critical overheating.
It is worth noting that piston compressors are most often used in household refrigerators, although there are also more modern rotary or spiral options in the premium segment. Each type of device has its own nuances, but the general principle of pressurization remains similar.
Why does the compressor heat up?
During operation, the compressor heats up to 80-90 degrees Celsius. This is normal, since when gas is compressed, the temperature inevitably increases. The casing is specially designed to dissipate this heat. However, if the temperature exceeds 110 degrees or the casing cannot be touched by hand for more than a second, this may indicate faulty valves or a lack of freon.
Differences between linear and inverter type
Traditional linear compressors operate on the “on-run-off” principle. They start up at full power, cool the chamber to the desired temperature and turn off. When the temperature rises, the cycle repeats. This mode of operation creates a characteristic noise when starting and stopping, and also leads to temperature changes inside the refrigeration chamber.
Inverter models, which are increasingly found in technology Samsung, LG and Whirlpool, work differently. They do not turn off completely after reaching the set temperature. Instead, they reduce engine speed, maintaining the temperature at minimum power.
This allows for several advantages. Firstly, the noise level is reduced, since there are no sharp starting currents and vibrations at start-up. Secondly, the temperature in the chambers remains more stable, which has a beneficial effect on the safety of products. Thirdly, the wear of mechanical parts is reduced.
However, inverter systems also have their own characteristics. They are more sensitive to voltage changes in the electrical network. For their stable operation, the installation of a voltage stabilizer is often required, especially in houses with old wiring. Repair of such compressors is also more expensive due to the complexity of the electronics.
When choosing equipment, it is worth considering these differences. If quietness and durability are important to you, an inverter will be your best choice. If the budget is limited, a classic linear compressor will also cope with its task, although it will work a little noisier.
Typical faults and diagnostic methods
A compressor is a complex mechanism, and its operation can be disrupted for various reasons. One of the most common problems is the failure of the start relay. In this case, you may hear a clicking sound followed by a humming sound from the motor, but it will not start. After a while, another click is heard, and the engine stops.
Another common reason is a break or inter-turn short circuit in the motor windings. This can happen due to a voltage surge or natural aging of the insulation. Diagnostics at home is possible using a multimeter: you need to test the windings for resistance and check for breakdown on the housing.
Mechanical wear of the piston group or valves is also common. Symptoms may include poor cooling during continuous operation of the engine or the absence of the characteristic sound of liquid flowing in the tubes. In some cases, the compressor may work, but not create the required pressure.
It is important to distinguish a compressor breakdown from a freon leak or a clogged capillary tube. In the last two cases, the motor itself may be in good order, but the system does not work due to a violation of the refrigerant circulation.
| Symptom | Possible cause | Actions |
|---|---|---|
| Buzzes, but does not start | The starting relay is faulty or jammed | Replace the relay, call a technician |
| The housing gets very hot | Lack of freon or wear | Check the pressure, look for leaks |
| Works without stopping | Freon leak or thermostat failure | Diagnostics of the cooling system |
| Strong vibration and noise | Destruction of the motor suspension inside the casing | Replacing the compressor |
⚠️ Attention: It is strictly forbidden to open the sealed compressor casing at home. There may be gas under pressure inside, as well as oil vapor. In addition, a violation of the tightness makes further repairs impossible without special equipment.
Noises and vibrations: normal or breakdown?
A running refrigerator makes sounds, and this is normal. However, the nature of the noise can tell a lot about the condition of the equipment. A uniform hum, which either increases or decreases, is the normal operating mode of a linear compressor. Quiet gurgling or hissing indicates the movement of freon through the tubes.
The alarm should be sounded if new, uncharacteristic sounds appear. Metallic clanging, knocking or rattling may indicate that the internal motor mount has collapsed and it has begun to touch the walls of the casing. Also, a source of noise can be loose mounting bolts or contact of tubes with the refrigerator body.
Vibration is another important indicator. Light vibration of the housing when the motor is running is acceptable. If the refrigerator begins to “ride” on the floor or vibration is transmitted to nearby objects, it is necessary to check the adjustment of the legs and the evenness of the installation.
Sometimes the cause of the noise is the compressor itself, if it has worn out bearings or deformed parts. In such cases, the noise usually increases over time.
- 🔊 Uniform hum - normal operation of the electric motor.
- 💧 Gurgling - refrigerant circulation (especially audible after switching off).
- 🔨 Knock or clanging is a sign of mechanical destruction internal components.
If you notice a sudden change in sound, try defrosting the refrigerator. Sometimes ice freezing on the evaporator or in the No Frost system can create a resonance that increases noise.
Extending the life of the compressor
The compressor is one of the most expensive components of the refrigerator, and replacing it is often not economically feasible. To extend its life, it is necessary to follow a number of operating rules. First of all, this concerns the installation of the unit. The distance to the rear wall must be at least 10 cm for free air circulation.
Overheating is the main enemy of the compressor. Do not place the refrigerator near a radiator, stove, or in direct sunlight. Regularly cleaning the condenser (grid at the back) from dust also helps efficient heat transfer.
It is important not to overload the refrigerator with food, especially in the first hours after loading. A sharp increase in temperature inside causes the motor to wear out for a long time. You should also avoid opening doors frequently.
☑️ fridge care
If you are leaving for a long time, it is recommended to defrost the refrigerator, wash it and leave the doors ajar. This will prevent the appearance of mold and odor, and also give mechanical components a rest.
⚠️ Attention: Do not turn on the refrigerator immediately after transportation if it was in a horizontal position. The oil must drain back into the compressor, otherwise water hammer may occur during startup. The minimum downtime is 4 hours, preferably 8-10.
Questions and answers (FAQ)
How long does a compressor last in a refrigerator on average?
The service life of a compressor depends on the type and operating conditions. Modern linear compressors last on average 10-15 years. Inverter models, due to the absence of constant starts, can operate for 20 years or more. However, the quality of the voltage in the network and regularity of maintenance also play an important role.
Is it possible to replace the compressor yourself?
Theoretically, you can replace the unit itself, but this requires special equipment: a vacuum pump, a pressure gauge station, a burner and soldering skills. In addition, precise refilling of freon of a certain type and in a strictly defined quantity is necessary. Without this, the refrigerator will not work. Therefore, it is better to entrust such work to professionals.
Why does the compressor turn on and off immediately?
This phenomenon is called “clocking”. Most often, the reason lies in a faulty starting relay, which cannot keep the engine in operating mode. Also, the cause may be an interturn short circuit in the motor windings or jamming of the piston group.
Does the room temperature affect the operation of the compressor?
Yes, it does significantly. Most refrigerators are designed to operate in climate class SN-T (from +10 to +38°C). If the room is colder than +10°C, the oil in the compressor thickens, making starting and lubrication difficult. If it is hotter than +38°C, the system does not have time to remove heat, and the compressor is overloaded.