The heart of any modern household refrigerator is the compressor. It is this unit that is responsible for creating the pressure necessary to circulate the refrigerant through the pipe system. Without its proper operation, it is impossible to maintain low temperatures in the chambers, which leads to rapid spoilage of food. Many owners of household appliances do not even think about what is behind the back wall until they encounter a breakdown.
Understanding the principles of operation of this mechanism allows you to notice deviations from the norm in time. Knowing how a working unit behaves, you can distinguish natural operating noise from signs of an impending disaster. In this article we will analyze in detail the physics of the process, operating modes and symptoms that require immediate intervention from a technician.
Normal operation implies the cyclic nature of the engine. It should not beep continuously unless you have loaded a huge amount of warm food into the chamber immediately after defrosting. In normal mode, the equipment alternates periods of activity and rest, maintaining a given temperature regime with minimal energy consumption.
Principle of operation and main stages of the cycle
Fundamentally, the cooling process is based on the compression of gaseous freon and its subsequent expansion. Compressor sucks refrigerant from evaporator, where it is in a state of low pressure steam. After compression, the gas is heated and sent under high pressure to a condenser, usually located on the rear grille.
In the condenser, the substance cools and turns into a liquid state, releasing heat to the environment. The flow then passes through a capillary tube or expansion valve, where the pressure drops sharply. Entering the evaporator inside the chambers, the liquid boils at a low temperature, actively absorbing heat from the products.
What is an inverter compressor?
Inverter models do not turn off completely, but only reduce engine speed when the desired temperature is reached. This avoids power surges and reduces noise levels, although the principle of gas compression remains the same.
It is important to understand that motor-compressor is a complex system where electrical energy is converted into mechanical energy. The piston, driven by the connecting rod mechanism, performs reciprocating movements. The tightness of the housing is critically important, since inside there is not only mechanics, but also part of the refrigerant with oil.
Normal operating cycle and duration of pauses
The ideal operation of a refrigerator is an alternation of phases. The engine turns on, builds up pressure until the thermostat reaches the set values, and turns off. Working and resting times depend on many factors: room temperature, amount of food and frequency of door opening.
On average, a working unit works for about 20–40 minutes, followed by a pause of the same duration. However, these numbers may vary. If the room is hot, the work cycle is longer and the downtime is reduced. This is a normal reaction of the system to external conditions.
There is a concept working time coefficient. For household models, a value of about 0.3–0.5 is considered the norm. This means that the engine is active for a third or half of the time of the day. If this indicator shifts towards 0.8 or higher, this is a signal of overload or freon leak.
It is worth noting that modern electronically controlled models may have different algorithms. They are able to predict the load and adjust the duration of cycles. However, the basic principle - the presence of rest periods to cool the motor windings - remains unchanged for most classical systems.
Sound diagnostics: what is considered normal
Acoustic comfort is an important aspect of operation. A working refrigerator emits a smooth, low-frequency hum. This sound is caused by the vibration of the piston group and the flow of liquid in the tubes. The noise level usually does not exceed 36–40 dB, which is comparable to a quiet whisper.
In addition to the hum, gurgling sounds or a slight hiss may be heard. This refrigerant flows through the system, changing its state of aggregation. Such sounds are especially noticeable immediately after turning off the engine, when the pressure in the system equalizes. This is absolutely normal and does not require repair.
⚠️ Attention: If you hear a loud metallic clang, knocking or high-pitched whistle when starting or stopping, this is a sign of mechanical wear of the liners or problems with the valve group. Ignoring such sounds can lead to jamming of the piston.
Vibration of the housing also occurs, but it should be barely noticeable. If the refrigerator begins to “walk” around the kitchen or rattles so that dishes on the shelves clink, check the adjustment of the legs. Often the problem lies in incorrect installation, and not in motor failure.
Temperature conditions and housing heating
During the compression process, the gas heats up very much, so the compressor housing and discharge tube (discharge) are always hot. A surface temperature of up to 50–60 degrees Celsius is considered normal. The hand can tolerate such heat, but it is unpleasant to hold the palm for a long time.
If the metal is heated to the point where it is impossible to touch it, or the color of the paint has changed (yellow or brown spots have appeared), this is an alarming symptom. Overheating can be caused by contamination of the condenser at the back, a fan malfunction (in No Frost systems) or loss of compression.
On the other hand, if the engine is running but remains cold, and the chambers are warm, most likely there is a freon leak or a blockage of the capillary system. In this case, circulation the refrigerant is broken, and heat exchange does not occur, although the motor tries to idle.
The table below will help systematize the signs of the compressor condition by external manifestations:
| Parameter | Normal condition | Symptoms of malfunction | Possible cause |
|---|---|---|---|
| Sound | Smooth low hum | Knocking, clanging, buzzing with interruptions | Bearing wear, valve failure |
| Case temperature | Hot (50-60°C) | Hot or icy | Overload, leakage freon, breakdown |
| Cyclicity | Work and rest 50/50 | Works non-stop or does not turn on | Lack of refrigerant, thermostat failure |
| Vibration | Barely noticeable | Strong shaking of the body | Unbalance, wear of shock absorbers |
The role of the starting relay and engine protection
The compressor electric motor is started using a start relay. This small element supplies a short-term impulse to the starting winding to spin the shaft. After a set of revolutions, the relay turns off this winding, and the engine runs on the main one.
If you hear a click, followed by a hum that lasts a few seconds, and again a click with a shutdown, this is the work of thermal protection. The engine is trying to start, but something is preventing it from gaining momentum. Most often, a stuck starting relay or an interturn short circuit in the windings is to blame.
☑️ Startup diagnostics
Thermal protection relay is installed to prevent fire. It opens the circuit if the current exceeds the norm or the temperature of the windings becomes critical. Frequent protection activations indicate that the compressor is operating in extreme mode and requires diagnostics.
In some cases, the problem is solved by replacing the relay, which is an inexpensive procedure. However, if after replacing the relay the symptoms repeat, the problem lies deeper - in the electric motor or the mechanical part of the unit.
Typical signs of compressor malfunction
There are a number of clear indicators indicating that the resource of the unit is coming to an end or has already been exhausted. The first and most obvious is that the refrigerator has stopped freezing, while the motor either hums continuously or is silent. If it is silent and does not vibrate, the winding may have burned out.
The second sign is the appearance of a burning smell or scorched wiring in the area of the engine compartment. This indicates overheating of the wire insulation or oil. It is strictly prohibited to operate equipment in this condition, as there is a high risk of fire.
⚠️ Attention: Never try to open the sealed compressor casing yourself. Freon may be under pressure inside, and oil vapors will ignite when in contact with an open flame or spark. Repairing such a unit requires special equipment.
The third symptom is the knocking out of plugs or circuit breakers in the apartment when the refrigerator is turned on. This is a direct sign of a short circuit in the motor circuit. Further switching on will only lead to damage to the electrical wiring of the home.
Factors shortening the service life
The service life of a modern compressor is 10–15 years, but real figures are often less. The main enemy is overheating. Installing the refrigerator close to the wall, in a niche without ventilation, or next to heating devices forces the motor to work at its limit.
Frequent power surges in the electrical network are also destructive. Electronics and motor windings do not like sudden changes. Using a voltage stabilizer or at least a high-quality surge protector can significantly extend the life of equipment, especially in areas with unstable power supplies.
Another factor is the quality of the oil. Over time, it loses its lubricating properties, oxidizes when overheated and turns into acid, which corrodes the windings from the inside. Regular preventive maintenance, which consists of cleaning the condenser from dust, helps maintain optimal temperature conditions.
Remember that loading the chamber with warm products creates a peak load. It's best to cool soup pots to room temperature before putting them on the shelf. This will reduce the number of intensive engine operation cycles per day.
Is it possible to repair a compressor?
Theoretically, rewinding the windings or replacing valves is possible in specialized workshops. However, in practice, the cost of such repairs, taking into account sealing and refilling with freon, often approaches the price of a new unit, so a complete replacement of the unit is often recommended.
Frequently asked questions (FAQ)
Why is the compressor humming, but the refrigerator does not freeze?
Most likely, there is a leak refrigerant. The motor runs, trying to create pressure, but gas has escaped from the system through a microcrack. It is also possible that the capillary tube may become clogged. You need to call a technician to find the leak and refill it.
Is it normal for the refrigerator to vibrate during operation?
Slight vibration is acceptable. If it is strong, check whether the appliance is level. Tighten the adjustable legs so that the body does not wobble. Also make sure that the internal shelves and bottles are not in contact with the walls.
How often should the compressor turn on?
Under normal conditions (room temperature +20°C), the work-rest ratio is approximately 1:1. In hot weather, operating time can increase to 70-80% of the total time. Continuous operation without stopping is permissible only during the first load or defrosting.
Is it possible to lubricate the compressor if it starts to make noise?
No, the compressor is a sealed unit that does not require or allow external lubrication. Noise indicates internal wear on mechanical parts. The lubricant from the outside will not get to the rubbing parts, but will only collect dust.