The refrigerator is one of the most important electrical appliances in every home, ensuring the safety of food. The heart of this complex system is compressorwhich is often called a motor. The ability of the unit to maintain the set temperature inside the chambers depends on its proper operation. Understanding the principles of operation of this unit will help the owner notice the first signs of malfunction in time.
Many users take the hum of the refrigerator for granted, without thinking about the physical processes occurring inside the metal case. However, if you listen, you can notice changes in the nature of the sound or the duration of the engine operation. Inverter models, for example, they operate much quieter than their classic counterparts, which often confuses inexperienced owners who are accustomed to cyclic switching on and off.
In this article we will examine the internal structure in detail compressor, we will look at the stages of refrigerant circulation and discuss common problems that users encounter. Knowing these nuances will allow you not only to operate the equipment correctly, but also to communicate reasonedly with the technician when calling for repairs. The cooling efficiency directly depends on the condition of the motor.
Principle of operation of a refrigeration compressor
The main task of the motor is to create the pressure necessary to circulate the refrigerant through a closed circuit of the system. Compressor sucks freon gas from the evaporator, compresses it and sends it under high pressure into the capacitor. This process is accompanied by a significant increase in gas temperature, which explains the heating of the rear grille of the refrigerator.
Classic models use a piston mechanism driven by an electric motor. The piston moves back and forth, creating a pressure difference in the system. Modern linear inverter compressors work on a different principle, eliminating the crank mechanism, which reduces the number of rubbing parts and the noise level.
Cyclical operation is ensured by a thermostat or an electronic control module. When the temperature in the chamber rises above the set value, the electrical circuit is closed and the motor starts. After reaching the desired cold, the circuit opens and the engine stops until the next cycle.
⚠️ Attention: If you notice that the refrigerator motor has been running non-stop for days, do not under any circumstances try to forcefully turn it off with a button or by pulling the plug. This can lead to jamming of the piston group due to lack of lubrication or overheating of the windings.
A critical element is the timely shutdown of the engine when target values are reached. Constant wear and tear reduces the life of the device by several times.
Main types of compressors in household appliances
The household appliances market offers several types of engines, each of which has its own design features. Piston compressors remain the most common due to their reliability and maintainability. They can be equipped with one or two motors, especially in models with a No Frost system for independent control of temperatures in different chambers.
Inverter motors are a more modern solution. They do not turn off completely, but only reduce the speed to maintain the temperature. This avoids constant voltage surges during startup and reduces energy consumption. Digital Inverter technology from Samsung or Linear Inverter from LG have become the standard for energy efficiency.
- 🔹 Static type: a classic piston motor with a crank mechanism that requires oil for lubrication.
- 🔹 Inverter type: brushless motor with continuously variable shaft rotation speed.
- 🔹 Linear type: the piston moves due to electromagnetic forces, excluding friction points.
The choice of compressor type affects not only the price of the refrigerator, but also the cost of its future maintenance. Repair of inverter models often requires replacing the entire assembly, since they are less amenable to local restoration.
Why are inverters quieter?
Inverter compressors are quieter because they do not have the “starting jerk” effect. A conventional motor starts working at maximum speed each time, creating a characteristic hum, while the inverter only smoothly changes the rotation speed, remaining in the background.
Design and internal components of the motor
Structurally, the compressor is a sealed metal casing, inside which all the working elements are located. Electric motor and the mechanical part (cylinder, piston, valves) are located in a single housing filled with inert gas and oil. This tightness prevents freon leaks and moisture from entering the system.
In the lower part of the casing there is a motor frame on which the stator and rotor are mounted. The rotor shaft drives the compressor crankshaft. To protect against overheating, a thermal relayis installed on the housing or inside the windings, which opens the circuit when the temperature rises critically.
The lubrication system is also built into the design. The oil is located at the bottom of the casing and is sprayed onto the parts or fed through special shaft channels under the influence of centrifugal forces. Lack of normal oil circulation is one of the main reasons for failure.
| Component | Function | Material |
|---|---|---|
| Stator | Creating a magnetic field | Copper wire, electrical steel |
| Rotor | Motor shaft rotation | Steel, aluminum plates |
| Piston | Compression refrigerant | Cast iron, steel |
| Valve group | Gas flow adjustment | Elastic steel, composites |
All connections inside the casing are made by soldering or welding, which makes them non-separable in domestic conditions. Opening the housing requires special equipment and evacuation of the system after repair.
The role of the starting relay and thermal protection
Starting the compressor electric motor is impossible without a special device - starting relay. Since the motor windings have high resistance, a powerful pulse of current is required to start. The relay supplies voltage to the starting winding only at the moment of startup, after which it turns it off, leaving only the main one to work.
In parallel with this, the thermal protection system operates. The bimetallic strip inside the relay responds to current and temperature. If the motor is overloaded or jammed, the current increases, the plate heats up and opens the contacts. This prevents the windings from burning out and causing a fire hazard.
- 🔸 Posistor: a modern element in starting relays that changes resistance when heated, cutting off the starting winding.
- 🔸 Electromagnetic relay: a classic version, where the current draws in the core, closing contacts.
- 🔸 Thermal relay: reacts exclusively to the heating of the housing or windings, performing an emergency shutdown function.
A frequent reason that the refrigerator hums but does not start is It's the start relay that's faulty. It may “stick” in a closed state or, conversely, not send an impulse to start.
Diagnostics of motor malfunctions
You can identify a problem with the compressor by a number of external signs. Overheating The motor housing (when it is impossible to touch it) indicates an interturn short circuit or problems with the cooling system. Normally, the engine should be hot, but not scalding.
The nature of the sound also says a lot about the condition of the unit. Metallic knocking, grinding or loud humming with vibration indicate mechanical wear of parts: bearings, piston group or valves. If the motor is silent, although the indicator is on, the winding may have burned out or the relay has failed.
Checking the compressor with a multimeter is the most accurate diagnostic method. It is necessary to ring three terminals on the case (common, starting, working). The resistance between them must be within certain limits (usually 10-30 Ohms). If the device shows infinity (open circuit) or zero (short circuit), the motor is faulty.
⚠️ Attention: Before taking any measurements with a multimeter, be sure to disconnect the refrigerator from the power supply. Working with live electrical circuits is deadly.
It is also worth checking the resistance between the terminals and the housing. If the current “breaks through” to the housing, it is prohibited to operate such a compressor, as this can lead to an electric shock when touching the metal parts of the refrigerator.
☑️ Symptoms of compressor failure
Typical problems and methods for eliminating them
One of the most common problems is hydraulic hammer. It occurs if liquid freon instead of gaseous freon enters the compressor cylinder. The fluid does not compress, which leads to destruction of the valves or even the piston. Most often this happens due to improper refueling or severe hypothermia.
Clogged capillary tube also creates excess pressure that the motor cannot cope with. In this case, the compressor may run constantly, trying to pump up pressure, but no cold is produced. The system needs to be purged and the filter-drier needs to be replaced.
Freon leakage is another reason for incorrect operation. The motor runs idle, trying to create pressure in an empty system. Visually This can be seen by swelling of the side walls of the refrigerator (where the condenser is sealed) or oily spots under the unit.
To eliminate most of these problems, you need to call a specialist. Replacing a compressor yourself is only possible if you have the skills to solder copper pipes, a vacuum pump and knowledge of refrigerant charging.
Prevention and extension of service life
In order for the refrigerator motor to serve for a long time, it is necessary to provide it with the correct operating conditions. Ventilation is a key factor. The rear grill of the refrigerator should be at least 5-10 cm from the wall. If heat is not removed, the compressor will overheat and wear out faster.
Regular defrosting (for drip systems) prevents the formation of an ice coat, which impairs heat transfer and makes the motor work longer. You should not load hot products into the chamber - this creates a sharp thermal load on the system.
- 🔹 Stable voltage: use a surge protector or stabilizer if there are power surges in your network.
- 🔹 Cleanliness: periodically vacuum the condenser at the back of the refrigerator, removing dust and wool animals.
- 🔹 Horizontalness: make sure that the refrigerator is level, otherwise the oil in the compressor may flow unevenly.
Following these simple rules will significantly increase the life of an expensive unit. Remember that replacing a compressor is often not economically feasible and is comparable to the cost of a new refrigerator.
Why does the compressor get very hot?
Heating of the compressor is a normal physical process of gas compression. However, if the temperature exceeds 90 degrees, this may indicate a blockage in the system, a freon leak, a malfunction of the cooling fan (in No Frost) or wear on the motor. Also, the reason may be that the room temperature is too high.
Is it possible to replace the compressor with an analogue?
Yes, but the parameters must be strictly observed: power, type of refrigerant, cylinder volume and overall dimensions. There are no universal solutions, and installing an unsuitable motor will lead to rapid failure of the entire system.
How long does a compressor last on average?
The average service life of a modern compressor is from 10 to 15 years with proper operation. Inverter models claim a resource of up to 20 years or more due to the absence of constant starting loads.