Refrigerator motor: what's inside and how it works

When the usual buzzing in the kitchen gives way to alarming silence or, conversely, a suspicious knock appears, most owners immediately remember the main thing unit unit. It compressor is often called the heart of the refrigeration system, and the safety of your products directly depends on its serviceability. Understanding what is inside this metal barrel helps not only to diagnose the problem, but also to avoid unnecessary expenses on the services of specialists in case of simple breakdowns.

Hidden inside the sealed housing is a complex mechanical system operating under high pressure. Many people mistakenly believe that there is a simple electric coil there, but the real design is much more complex and reliable. By understanding the details, you can better understand the operating principles of your Indesit, Bosch or any other brand.

The main task of this unit is to compress the refrigerant and ensure its circulation throughout the circuit. If you hear strange sounds or notice that your equipment has stopped freezing, the problem often lies in the internal components of the engine. Let's study in detail the anatomy of this mechanism.

The principle of operation of the compressor unit

The fundamental principle of operation is to convert electrical energy into mechanical movement of the pistons. Electric motorlocated inside the housing, rotates the crankshaft, which, in turn, sets the piston group in motion. This process is reminiscent of the operation of a car engine, but with one key difference - all processes occur in a closed, sealed space.

When the piston moves down into the cylinder through the intake valve, low pressure gas is drawn in. When the piston begins to move upward, the valve closes and the gas is compressed. Once the pressure reaches a certain level, the release valve opens and the compressed hot gas is pushed into the condenser grille on the back wall of the refrigerator. freon low pressure. When the piston begins to move upward, the valve closes and the gas is compressed. Once the pressure reaches a certain level, the release valve opens and the compressed hot gas is pushed into the condenser grill on the back wall of the refrigerator.

⚠️ Attention: Inside the compressor housing there is oil and refrigerant under pressure. It is strictly forbidden to open the sealed casing at home without special equipment and skills, as this can lead to depressurization of the system and failure of the unit. It is important to note that in modern models, such as inverter systems, the principle remains the same, but the way the motor is controlled changes. Instead of cycling on and off, the motor can smoothly change rotation speed, which reduces wear on parts.

It is important to note that in modern models such as LG Linear or inverter systems Samsung, the principle remains the same, but the way the engine is controlled changes. Instead of cycling on and off, the motor can smoothly change rotation speed, which reduces wear on parts.

Design features: what the motor consists of

If you look inside the casing (relatively, cutting it), we will see several critical components. The central place is occupied by itself electric motor, consisting of a stator and a rotor. The rotor is rigidly fixed to the crankshaft, which passes through the entire structure. At the opposite end of the shaft there are connecting rods connected to the pistons.

All these mechanics are immersed in a special compressor oil. It is necessary not only for lubrication of rubbing parts, but also for heat removal and additional sealing of the gaps between the piston and cylinder. The quality and level of oil directly affect the service life of the unit.

There is also a complex system of valves and springs located inside. They ensure the unidirectional movement of the refrigerant. Often, it is a breakdown of the valve plate or weakening of the springs that causes the refrigerator to stop gaining temperature, although the motor is humming.

Why does the motor hang on springs?

Inside the casing, the entire mechanism is suspended on three or four internal springs. This is done to dampen vibrations that occur during operation of the piston group, so that noise is not transmitted to the refrigerator body.

The start-up protection relay deserves special attention, which is mounted externally on the terminals of the windings, but is functionally part of the starting system. It provides the initial impulse for start and turns off the starting winding after gaining speed.

Types of compressors: piston and inverter

In the household appliances market, including popular brands like Atlant or Whirlpool, there are two main types of designs. Understanding the difference between them will help when choosing new equipment or estimating the cost of repairs.

Classic piston compressor works on the principle of reciprocating movements. It is either on full power or off. This creates characteristic noise differences and temperature fluctuations inside the chambers. Such models are easier to repair, but consume more electricity.

Inverter models, on the contrary, work constantly, but with different intensities. They use a motor with variable shaft speed. This allows you to maintain the set temperature with an accuracy of a degree without stopping the motor.

It is worth considering that the electronics of inverter systems are more sensitive to power surges in the network. To protect such expensive units as Siemens or Haier with an inverter, it is recommended to use voltage stabilizers.

Start relay: the brain and heart of the start

Although the start relay formally located outside, its role in the operation of the “motor” cannot be overestimated. It is this small plastic block that is responsible for supplying current to the starting stator winding at the moment of switching on. Without this initial push, the rotor would simply hum without starting to rotate.

Inside the relay there is a coil and a movable core (or a posistor in modern models). When voltage is applied, current flows through the starting winding, creating a magnetic field that draws in the core and closes the contacts. As soon as the engine picks up speed, the current drops and the relay opens the starting winding circuit.

A common problem is sticking of the contacts or burnout of the posistor. In this case, you can hear characteristic clicks every few minutes: the refrigerator is trying to start, the relay clicks, but the motor does not start. After some time, the thermal protection is triggered and the cycle repeats.

Replacing the relay is one of the simplest and cheapest repair procedures. It is enough to remove the cover, photograph the connection diagram and replace the part with a similar one. However, if the new relay burns out immediately, the problem lies deeper - in the windings of the motor itself.

Diagnostics of faults by sound and symptoms

An experienced technician can determine an internal breakdown simply by listening to the operating unit. Sound diagnostics allows you to localize the problem without disassembling. For example, a loud metallic clang upon startup often indicates that the “springs” holding the motor inside the casing have burst, and the mechanism is hitting the walls.

If you hear a quiet hum, which ends abruptly with a click, and repeats cyclically, most likely the piston is jammed or the compression resource has been exhausted. In this case, the discharge pressure is not enough to open the valve, and the thermal relay is activated.

⚠️ Attention: If you smell burning wiring or see sparking in the motor area, immediately unplug the refrigerator. Operation in this condition may result in a fire.

Another important symptom is overheating of the case. Normally, the upper part of the compressor can be hot (up to 80-90 degrees), but if the entire casing is hot or you cannot touch the tubes, this is a signal of overload or lack of freon.

Is it possible to restore a jammed compressor?

There is a method of “wedging” by applying increased voltage or tapping, but this is a temporary measure. Mechanical wear will not go away, and the unit will soon jam again.

Maintenance and extending service life

Although the insides of the compressor are sealed and do not require changing oil or filters at home, external factors greatly affect its durability. The main task of the owner is to ensure the correct heat transfer. Dust and animal hair settling on the black grille of the condenser at the back create a “thermal coat.”

When the condenser is clogged, the compressor has to work longer and harder to cool the chambers. This leads to overheating of the oil, loss of its lubricating properties and accelerated wear of the piston group. Regular cleaning behind the refrigerator is the best prevention.

Proper installation is also critically important. If the refrigerator is located close to the wall or in a niche without gaps, the hot air has nowhere to escape. The motor operates in extreme conditions, which shortens its life significantly.

Do not forget about even installation. If the refrigerator is skewed, the oil may be unevenly distributed in the crankcase, which will lead to dry operation in the first seconds after startup. Use a building level to adjust the legs.

Why does the compressor get very hot?

Heating up to 70-90 degrees is the norm for a working compressor. However, if it is hot to the touch even when turned off or gets too hot to touch, the reasons may be: a freon leak (the motor runs without stopping), a clogged capillary tube, a malfunctioning thermostat or poor rear ventilation.

Is it possible to replace the compressor yourself?

Theoretically - yes, if you know how to work with tool. But in practice this is impossible without a vacuum pump, a pressure gauge station and a supply of freon. You cannot simply “re-solder” the pipes - the system must be evacuated and refilled with refrigerant strictly by gram. This is a job for the service center.

How long does a refrigerator motor last on average?

The average service life of a modern compressor is 10-15 years. Inverter models are claimed by manufacturers to last up to 20 years or more, but the actual period depends on the quality of the voltage in the network, the frequency of defrosts and operating conditions (room temperature).