When it stops being cold inside the refrigeration chamber and food begins to spoil, most The first thing owners remember is the main mechanism that ensures the circulation of the refrigerant. In everyday life, this unit is often called simply “engine,” although the technically correct name sounds different and implies a more complex design. Understanding exactly how this unit works will help you better navigate the symptoms of a breakdown and correctly formulate the problem when calling a technician.
The main power unit that creates pressure in the system is technically called compressor. It is he who is responsible for compressing freon gas and pushing it through the tubes of the condenser and evaporator. Inside the compressor housing there is an electric motor that drives the piston group or rotor, but in everyday life these two elements are often combined into one concept. Knowing this difference is important, since sometimes it is the mechanical part that breaks, and sometimes the electrical winding of the motor.
In modern models of refrigeration equipment you can find various types of these devices, from classic piston to innovative inverter systems. Linear compressors from LG or inverter motors from Samsung work according to fundamentally different schemes than their predecessors, released twenty years ago. The differences concern not only energy efficiency, but also the nature of the noise emitted, as well as the maintainability of the unit as a whole.
Technical name and principle of operation of the unit
So, if you are looking for a part in a spare parts catalog or discussing a breakdown with a service engineer, the correct term will be hermetic compressor. The word “sealed” is key here, since the device body is completely sealed and cannot be disassembled at home without special equipment. Inside this metal “barrel” there are both the electric motor itself and the compression mechanism, immersed in oil.
The operating principle is based on a continuous cycle of compression and expansion of the refrigerant. The motor starts, creating torque, which is transmitted to the shaft. Depending on the design, this movement is converted into translational movement of the pistons or oscillatory movement of the piston in linear models. Freonpassing through the system, it takes heat from the internal chamber of the refrigerator and releases it into the surrounding space through the grate on the rear wall.
⚠️ Attention: It is strictly forbidden to open the compressor housing yourself. There may be pressurized gas or oil vapor inside which, when combined with an open flame or spark, can be dangerous. Repair is possible only by completely replacing the unit.
It is important to understand that the engine in the refrigerator does not operate constantly, but cyclically. It is turned on by a signal from thermostat or the electronic control module when the temperature inside the chambers rises above the set one. After reaching the desired cold, the motor turns off. The only exceptions are inverter models, which can operate continuously, changing only the rotational power of the shaft.
Types of compressors in household appliances
The evolution of refrigeration technology has led to the emergence of several types of engines, each of which has its own operating characteristics. The most common option remained piston compressorfor many years. It is based on a classic scheme: an electric motor rotates the crankshaft, which pushes the piston up and down through a connecting rod. Such units are reliable, but create vibration and characteristic noise when starting.
A more modern development of steel inverter motors. Their main difference is the absence of a strict connection to the on and off cycles. The inverter smoothly regulates the shaft rotation speed, maintaining the temperature in the chamber with minimal deviations. This allows you to save energy and reduce wear on mechanical parts, since there are no peak current loads at start-up.
We should also mention linear compressors, which are often advertised as the pinnacle of engineering. They do not have rotating parts in the traditional sense. The piston is driven by electromagnetic forces, performing reciprocating movements. This makes the operation of the unit much quieter, but the sensitivity to the quality of the network voltage in such models is higher.
- 🔹 Piston: classical design, high noise level, maintainability (entire replacement), low cost.
- 🔹 Inverter: quiet operation, energy saving, complex control electronics, high price.
- 🔹 Linear: minimal vibration, durability, sensitivity to power surges.
Symptoms of a refrigerator motor malfunction
You can determine that the “heart” of your refrigerator is acting up by a number of indirect signs. The most obvious is the lack of cold when the backlight is on. However, before you panic, you should listen to the sounds that the device makes. If you hear a humming sound, but the engine does not start, or the engine clicks and immediately stalls, these are sure signs of a problem.
Often owners notice that compressor it begins to work longer than usual or does not turn off at all. This may indicate both a loss of tightness of the circuit (freon leakage) and wear and tear of the motor itself, which cannot gain the required pressure. In such cases, the engine wears out, trying to compensate for the inefficiency of the cooling system.
⚠️ Attention: If you smell burning wiring or see sparking in the compressor area, immediately unplug the refrigerator. The operation of faulty electrical equipment can lead to a fire.
Another alarming signal is excessive heating of the compressor housing. Normally, it should be warm or hot (depending on the phase of the cycle), but if it cannot be touched without being burned, and the refrigerator compartment does not freeze, there is a serious malfunction. Perhaps the piston group is jammed or the winding is burned out.
Why is the compressor hot but not cold?
This is a classic sign that the motor is working, but is not pumping freon. Either the rod has broken inside, or a blockage has formed in the system (often in the capillary tube), or gas has completely escaped. In any case, you need to call a specialist.
Table of main faults and their symptoms
For a more accurate diagnosis, it is useful to compare the observed symptoms with typical problems. Below is a table that will help you navigate the situation before the specialist arrives. Remember that an accurate diagnosis can only be made by a specialist with a pressure manifold and a tester.
| Symptom | Probable cause | Necessary actions |
|---|---|---|
| It buzzes, but does not start, it clicks after a while | The starting relay is faulty or the compressor is jammed | Replacing the relay, checking the windings |
| Works constantly, without turning off | Freon leakage or compressor wear | Search for leaks, refueling or replacing the engine |
| Strong vibration and noise during operation | Destruction of shock absorbers or wear of bearings | Replacement of shock absorbers, less often - replacement of the compressor |
| Knocks out the machine in the dashboard when switching on | Short circuit in the motor winding | Urgent replacement of the compressor |
Diagnostics of the electrical part usually begins with checking the resistance of the windings. A multimeter is used for this. Normal resistance values for different windings (starting and operating) may differ depending on the model, but they should always be within tens of ohms. If the device shows zero or infinity - engine burned out.
It is also important to check the integrity of the chassis ground circuit. A breakdown of the winding insulation on the housing is a common reason why a refrigerator can be “pinched” by current or knock out an RCD. In such cases, the operation of equipment becomes life-threatening.
Why does the engine hum and vibrate
Noise when the refrigerator is operating is a normal phenomenon, but its nature may change. If a previously quiet device suddenly begins to hum like a transformer box, it’s worth looking for the reason. Often it's not the motor itself, but how it's mounted. The compressor is installed on special shock absorbers that dampen vibrations.
Over time, the rubber bushings dry out and crack, and metal begins to touch metal, creating a resonating hum. Sometimes vibration is transmitted to the body of the refrigerator or to the tubes leading to the motor. If the tubes are located too close to each other, they may touch and rattle when the piston group operates.
- 🔸 Check that the refrigerator body is not touching the wall or furniture.
- 🔸 Inspect the shock absorbers under the compressor for cracks.
- 🔸 Carefully (with the power off!) try to shake the tubes with your hands - if they dangle and ring, they need to be carefully bent.
☑️ Diagnosis of refrigerator noise
If the hum comes from inside the compressor “barrel” and is accompanied by a metallic clang, this indicates about mechanical destruction of internal components. In this case, unfortunately, replacement is inevitable. Modern sealed units are not designed for internal repairs in a service center.
Replacing a compressor: is it worth doing it yourself
Theoretically, you can replace the motor in a refrigerator with your own hands if you have the skills to work with power tools and soldering. However, in practice, this is one of the most difficult procedures in repairing household appliances. It requires not only technical skill, but also specific equipment, which not every home craftsman has.
For a quality replacement, you must have a vacuum pump for pumping out the system, a pressure gauge station for monitoring pressure and scales for accurate filling. freon. In addition, the process of soldering copper tubes requires care not to overheat the system and prevent oxidation of the copper from the inside, which will lead to rapid failure of the new compressor.
⚠️ Attention: Incorrect soldering or insufficient evacuation of the system will lead to the new compressor burning out after a few months. Moisture and air in the circuit are the main enemies of the refrigeration system.
Another important aspect is the selection of a compatible model. Compressors have different parameters: power, refrigerant (R134a, R600a), oil type and overall dimensions. Installing an unsuitable motor can lead to incorrect operation of the refrigerator or its complete failure.
How to extend the life of a refrigerator motor
In order for the compressor of your refrigerator to serve as long as possible, you need to provide it with the correct operating conditions. First of all, this concerns ventilation. The back of the device must be at a sufficient distance from the wall so that the heat from the condenser can dissipate freely. Overheating is the main enemy of the electric motor.
Regular defrosting (for No Frost systems this is not required, but drainage control is needed) and cleaning the heat exchanger from dust are also important. A layer of dust of several millimeters on the radiator at the back of the refrigerator significantly impairs heat transfer, causing the motor to work longer and more intensely.
You should not load too much warm food into the chamber. A sharp jump in temperature forces the engine to work at the limit for a long time, which reduces its resource. Let food cool to room temperature before sending it into the cold.
Voltage stability is another factor in longevity. Voltage surges can damage the start relay or pierce the insulation of the windings. Using a surge protector or voltage stabilizer will be an excellent investment in the safety of equipment.
Is it possible to replace an old compressor with a more powerful one?
Technically this is possible, but it is extremely undesirable without deep knowledge of thermodynamics. A more powerful motor will create excess pressure that the condenser and evaporator may not be able to handle. This will lead to ruptured tubes or rapid wear of the system. It is better to install the original or a complete analogue.
Why is the new refrigerator louder than the old one?
Modern refrigerants (for example, R600a) require more precise system settings and sometimes create a specific gurgling sound that was absent in older R12 models. Also, new motors can operate at higher speeds to achieve energy efficiency.
How long does a compressor last on average?
The average service life of a high-quality compressor is 10-15 years. Inverter models can work longer - up to 20 years or more, due to the absence of constant start and stop cycles, which wear out the mechanism the most.
What to do if the compressor gets very hot?
If the motor housing is so hot that it hurts to touch it, and the refrigerator does not freeze, this is an emergency mode. You need to unplug the device and let it cool for several hours. If after switching on the situation repeats, call a technician.
Is it possible to lubricate the compressor?
No, you cannot lubricate the outer casing or shaft (if it were available). Inside the compressor there is a special refrigeration oil that circulates along with freon. Adding extraneous lubricant will lead to a chemical reaction, the formation of acids and rapid failure of the system.