A modern refrigerator is a complex engineering structure, however its heart always remains the compressor and engine group. It is this unit that is responsible for circulating the refrigerant, creating the necessary pressure to remove heat from the inner chamber to the outside. Understanding how the motor in the refrigerator works allows owners to better understand the causes of breakdowns and more effectively plan equipment maintenance.
An electric motor is hidden inside the sealed casing, which drives a piston or rotating system. This process of converting electrical energy into mechanical work underlies the entire cooling system. Without a working compressor compressor, it is impossible for any household refrigeration unit to operate, be it an old Soviet model or a modern electronically controlled model.
Many users mistakenly believe that the motor runs constantly, but in fact its cyclicity depends on many factors. The ambient temperature, the degree of loading of the chambers and the condition of the seals directly affect the frequency of switching on. Let us examine in detail the internal structure and principles of operation of this critically important unit.
The basic principle of operation of the compressor unit
The main task of the motor is to compress the gaseous refrigerant and pump it through a system of tubes. When you turn on the refrigerator, electric current flows into the motor windings, creating a magnetic field. This field causes the rotor to rotate, transmitting torque to the compressor shaft. At this moment, the cooling cycle begins.
The movement of the piston inside the cylinder creates zones of rarefaction and high pressure. In the suction phase, freon gas is drawn from the evaporator, where it has absorbed heat from the products. Then a compression stroke occurs, during which the gas is heated and pushed under pressure into the condenser. It is here, in the coil on the rear wall, that the refrigerant releases heat to the atmosphere and turns into a liquid state.
⚠️ Attention: If you hear a loud metallic clanging sound when starting, this may indicate destruction of the engine mount or valve group. Operation in this mode will quickly damage the equipment.
It is important to note that the efficiency of operation directly depends on the tightness of the system. Any microcrack in the tubes or seals leads to loss of refrigerant and a drop in pressure. The motor begins to wear out, trying to compensate for the lack of freon, which often leads to its overheating and subsequent burning of the windings.
Internal structure of an electric motor
The design of the motor in a refrigerator is significantly different from those used in industry or power tools. It uses an asynchronous motor with a squirrel-cage rotor, designed for long-term operation in an aggressive environment. All components are immersed in refrigeration oil, which performs the functions of lubricating and cooling rubbing parts.
The engine stator is a core assembled from metal plates with copper windings. It is the quality of winding and insulation of wires that determines the service life of the entire unit. During voltage surges in the network, it is the windings that take the first blow, which can lead to an interturn short circuit. To protect against such situations, starting relay a thermal protection relay is used.
The rotor, or “squirrel cage,” is mounted on a shaft, which is eccentrically connected to the piston group. Modern models use precision sliding bearings operating in an oil bath. The absence of rubbing metal pairs (as in ball bearings) significantly reduces the noise level and increases service life.
Why is the motor sealed?
A sealed casing is necessary to prevent freon leakage and moisture from entering the system. Moisture in the cooling system causes blockage of the capillary tube with ice and a chemical reaction with the oil, forming an acid that corrodes the windings.
In addition, additional elements are located inside the casing, such as noise mufflers and shock absorbers. They are necessary to dampen vibrations that occur when the piston moves. If these elements fail, the refrigerator begins to vibrate and rattle strongly, creating discomfort in the room.
Varieties of compressor technologies
Technical progress has not spared the refrigeration industry, offering several types of motors. Traditional piston compressors remain the most common due to their reliability and maintainability. However, they have a fixed shaft rotation speed, which leads to a cyclic operating mode: switching on at full power and completely switching off.
A more advanced solution is inverter motors. Their key difference is the ability to smoothly change the rotation speed. Instead of constantly starting and stopping, the inverter compressor runs continuously, only adjusting power depending on the need for cooling. This allows you to achieve high energy efficiency and low noise levels.
- 🔹 Piston: classic design, affordable price, high noise level at start.
- 🔹 Inverter: quiet operation, energy saving, high sensitivity to voltage changes.
- 🔹 Linear: no rotating parts, the piston moves by electromagnetic forces, minimum vibrations.
Linear compressors, often found in premium technology, operate on the principle of reciprocating magnet movement. The absence of a crank mechanism makes them incredibly durable. However, the cost of repairing such components is much higher, and spare parts are less common.
The role of the starting relay and thermostat
The motor itself will not be able to start without a control system. The key element here is the start relay. When the refrigerator is turned on, the rotor is motionless, and to dislodge it requires a current several times higher than the working one. The starting relay briefly connects the starting winding, creating the necessary torque.
As soon as the shaft picks up speed, the current in the windings drops, and the relay turns off the starting circuit. If this mechanism gets stuck in the closed position, the starting winding burns out in a matter of seconds. If the relay does not close, the motor hums, but does not start until the thermal protection is triggered.
The whole process is controlled by a thermostat or an electronic module. It reads temperature sensors inside the chamber. When the temperature rises above a predetermined threshold, the circuit closes and voltage is applied to the motor. When the desired cold is reached, the power is turned off.
⚠️ Attention: Frequent “blinking” of the relay (clicks every few seconds) indicates a faulty starter or a jammed compressor. Do not try to start the refrigerator repeatedly - this will lead to burnout of the windings.
In modern models with electronic control, the functions of the relay and thermostat are performed by a single controller. It analyzes many parameters, including operating time, capacitor temperature and network voltage, optimizing the operation of the motor for maximum efficiency.
Table of technical characteristics and parameters
To understand the scale of motor operation, consider the average technical parameters typical for middle-class household refrigerators. This data will help assess the load on the power grid and expected performance.
| Parameter | Value | Description of influence |
|---|---|---|
| Motor power | 100–250 W | Determines the cooling rate and energy consumption |
| Starting current | up to 15 A | Short-term load on the network at the time of startup |
| Discharge pressure | 15–20 atm | Critical parameter for freon circulation |
| Noise level | 36–42 dB | Depends on the type of compressor and quality depreciation |
| Operating life | 10 years+ | Subject to operating and ventilation conditions |
It is worth considering that actual performance may vary depending on the brand of refrigerant (R134a, R600a) and the design of the system. For example, refrigerators using isobutane (R600a) require less pressure and motor power, but are more sensitive to the cleanliness of the system.
Typical malfunctions and diagnostics
Understanding how the motor works helps to quickly diagnose problems. The most common fault is failure to start. If the refrigerator hums for 5-10 seconds, and then there is a click and silence, most likely the problem is in the start relay or a stuck piston.
Another symptom is continuous operation without shutdowns. This may indicate a freon leak, loss of compressor performance (ring wear), or a malfunctioning thermostat. The motor tries to compensate for the lack of cold by working at its limit, which leads to its overheating.
- 🔸 Overheating: often caused by contamination of the condenser at the back of the refrigerator or insufficient clearance at the wall.
- 🔸 Vibration: a sign of wear on the shock absorbers inside the casing or improper installation of the refrigerator itself on floor.
- 🔸 Burning smell: indicates a breakdown of winding insulation or melting of relay contacts.
For accurate diagnostics, technicians use a pressure gauge station, measuring the pressure at suction and discharge. Low suction pressure with high discharge pressure indicates low compressor performance, which is a direct indication for its replacement.
☑️ Diagnosis of motor problems
Operation rules to extend service life
In order for the refrigerator motor to serve as long as possible, it is necessary to provide it with comfortable working conditions. First of all, this concerns ventilation. The rear grille of the condenser must be freely washed by air. Installing the refrigerator close to the wall or in a niche without gaps leads to overheating and reduced service life.
It is also important to monitor the stability of the voltage in the network. Voltage surges destroy the insulation of the windings. Using a surge protector or voltage stabilizer will be an excellent investment in the longevity of your equipment, especially in areas with unstable power supply.
Don't forget about regular defrosting (for No Frost systems this is less important, but drainage control is necessary). Excessive humidity and ice jams create additional stress on the system, forcing the engine to work harder. Cleanliness inside the chamber and the absence of rotting products also indirectly affect the efficiency of heat transfer.
⚠️ Attention: Never turn on the refrigerator immediately after defrosting or transporting. The oil needs time (at least 2-4 hours) to drain into the compressor crankcase, otherwise water hammer and valve failure are possible.
By following these simple rules, you can significantly extend the life of the heart of your refrigerator. Remember that prevention is always cheaper than complex repairs or replacement of an expensive unit.
Why does the refrigerator hum loudly when starting?
Humming when starting is a normal process of the piston group when the motor overcomes inertia and pressure in the system. However, if the sound becomes metallic, rattling, or does not stop after starting, this may indicate wear on internal parts, loose compressor mounting bolts, or a faulty start relay.
Is it possible to replace the motor yourself?
Theoretically, replacement is possible, but requires specialized tools: a burner, a vacuum pump, and pressure gauges. In addition, the exact amount of refrigerant and oil must be charged. Without experience and equipment, there is a high risk of damaging a new compressor or creating an explosive mixture, so it is better to entrust such work to professionals.
How long does a compressor last on average?
The average service life of a modern compressor is 10-15 years during normal operation. Inverter models claim a service life of up to 20 years or more. However, the real figure greatly depends on the quality of the electrical network, the frequency of defrosts and ventilation conditions around the equipment.
What is “idling” of a compressor?
In domestic refrigerators, the concept of “idling” in the classical sense is absent. The compressor is either working to create pressure or has stopped. Operation without load (for example, if the suction tube breaks) leads to the fact that the motor is not cooled by the returning gas and quickly overheats, which is an emergency mode.