Many owners of household appliances are faced with a situation where the refrigerator stops cooling, and diagnostics indicate problems with the compressor. In the circles of masters, the term “decompression” is often heard, which raises many questions among ordinary people. In fact, we are talking about checking the ability to create pressure or, conversely, the loss of this ability of the internal compression engine.
Understanding the processes occurring inside a sealed unit allows you to more accurately diagnose a breakdown before calling a specialist. Decompression of a refrigerator motor is not just releasing pressure, but often a critical symptom of piston or valve wear. If the engine cannot create the necessary vacuum at the inlet and pressure at the outlet, cold will not appear in the chambers.
In this article we will analyze the physical essence of the process, diagnostic methods and the reasons why the compressor loses its power. You will learn how to distinguish a banal blockage from a mechanical breakdown and whether it is worth repairing an old unit at all. Accurate diagnostics will save you money and time.
The essence of the concept and the physics of the process
To understand what decompression is, you need to consider operating principle piston compressor. The refrigerator engine operates on the principle of a pump: it sucks gaseous refrigerant from the evaporator and pumps it under high pressure into the condenser. In good condition, the pressure difference between the suction and discharge tubes should be maximum.
When they talk about decompression, they often mean two states. The first is the process of bleeding freon before repair, which is a standard procedure. The second, more important for diagnosis, is loss of compression. In this case, the piston group is worn out, the rings are worn out, and the valves no longer seal the chambers tightly. Gas simply flows from one zone to another without creating the required pressure.
Physically it looks like this: the motor hums, vibrates, consumes current, but refrigerant circulation is absent or extremely weak. Without a pressure difference, freon cannot effectively transfer heat to the environment and remove it from the freezer. The result is a complete or partial loss of cooling capacity.
⚠️ Attention: Never try to check compression with your finger by pinching the outlet tube of a running engine. The pressure in the system can exceed 15-20 atmospheres, which will lead to serious injuries or burns from heated oil.
It is important to distinguish between the concepts of “decompression” as an action and as a condition. In maintenance this often means checking the residual pressure. If, after stopping the engine, the pressure in the system equalizes too quickly, this may indicate leakage of the valves.
Symptoms of loss of compression in engine
You can determine that the refrigerator motor has lost its power by a number of indirect signs. The first and most obvious symptom is the continuous operation compressor. Temperature sensors record that the cold is not achieved and give a command to work, but due to weak compression the required parameters do not occur.
The second sign is the temperature regime of the tubes. During normal operation, the discharge pipe (compressor outlet) should be hot and the suction pipe should be cold. If the motor is running, but both tubes remain warm or at room temperature, this is a sure sign that gas circulation gas circulation is broken
- 🔊 The motor hums smoothly, but the refrigerator compartments do not cool even after several hours of operation.
- ❄️ The evaporator inside the freezer remains warm or is covered with frost unevenly (only at the entrance).
- 🌡️ The condenser grille at the back of the refrigerator remains cold, although the compressor is hot.
- ⚡ Electricity consumption remains low or normal, but the cooling effect no.
Sometimes users confuse loss of compression with a freon leak. However, if there is a leak, the motor can be switched off by the thermostat, as the pressure in the system drops, and the emergency sensor opens the circuit. During decompression, the motor often works without stopping, trying to compensate for the lack of pressure.
It is also worth paying attention to the sound of operation. A worn-out compressor may produce characteristic clunking or hissing sounds, indicating that gases are leaking through the valves. This distinguishes it from a healthy unit, the operation of which is accompanied only by a steady hum.
Diagnostic methods compressor
To accurately determine the condition of the engine, it is necessary to take pressure measurements. Professionals use pressure gauge station, which connects to the process pipe. This allows you to see the real indicators of suction and discharge in dynamics.
At home, with minimal skills, you can carry out a visual check of the flow. To do this, carefully unsolder the capillary tube or filter drier. When a working engine is turned on, a powerful flow of air or gas should flow from the open tube. If the flow is barely felt by the palm, there is decompression.
Another method is checking the current characteristics. A worn motor may draw less current than its nameplate rating because it does not have to overcome the resistance of the compressed gas. However, the opposite situation is more often observed: the motor overheats and consumes more energy due to friction and idle operation.
⚠️ Attention: If the pipes are disconnected, oil may come out of the system. Be careful, use safety glasses and gloves, as refrigeration oil is aggressive to some types of plastic and rubber.
Diagnostics are also carried out by measuring the time of pressure build-up in a closed circuit. If the connected pressure gauge shows a slow increase or no increase in pressure, this confirms wear piston group. In some cases, it helps to check the bypass valve, which can get stuck in the open position.
☑️ Checking the compressor
Causes of the malfunction
The main reason for decompression is the natural wear of parts. Piston rings, made of cast iron or steel, wear away over time, increasing the clearance between the piston and the cylinder wall. Gas begins to flow through this gap, bypassing the compression stage. This is an irreversible process that depends on the service life of engine hours..
The second common cause is damage to the plate valves. They are thin metal plates that open and close thousands of times per minute. Overheating of the motor or moisture entering the system (which leads to the formation of acid) causes corrosion or deformation of the valves. As a result, they no longer fit tightly to the seat.
The third reason is mechanical destruction of the connecting rod and piston group. This can occur due to water hammer if liquid freon enters the cylinder instead of gas. The liquid is incompressible, and during the stroke of the piston a sharp impact occurs, which can break connecting rod or cylinder partitions.
The table below shows the main causes and their consequences for the system:
| Cause | Mechanism of occurrence | Result |
|---|---|---|
| Ring wear | Friction against the cylinder walls | Pressure drop, oil waste |
| Breakage valve | Metal fatigue, overheating | Gas flow, lack of compression |
| Water hammer | Ingress of liquid freon | Destruction of mechanical parts |
| Seizing | Lack of lubrication, carbon deposits | Motor stopping, humming |
It is important to note that prolonged operation of the refrigerator in abnormal conditions (for example, with a dirty condenser) accelerates wear. Overheating leads to a change in the properties of the oil and loss of lubricity, which also leads to decompression.
Is it possible to restore compression?
The issue of repairing a worn compressor is one of the most controversial. Theoretically, if you replace the piston group and valves, compression can be restored. However, in practice hermetic compressorsinstalled in household refrigerators are not intended for major repairs.
The housing of such a motor is welded at the factory. To open it, you need a grinder or special scissors, and for reverse sealing, you need high-quality welding in an inert gas environment. The cost of labor and spare parts often exceeds the price of a new compressor. In addition, finding original spare parts for a specific model engine is extremely difficult.
There are methods of “revival” by adding special additives to the oil or vacuuming the system. These methods may temporarily increase blood pressure, but the effect is usually short-lived. After a few months or even weeks, the problem of decompression returns, since mechanical wear does not go away.
Why shouldn’t you open the compressor yourself?
An opened and re-welded compressor loses its factory tightness. Even a microscopic gap will lead to the rapid release of freon and the entry of moisture, which will kill the new motor in a matter of weeks. In addition, the balancing of the rotor is disrupted, which causes strong vibration.
The only reliable way to restore the functionality of the refrigerator is replacement of the compressor entirely. The new unit guarantees the required compression parameters and reliability for several years to come.
Replacement of the compressor or purchase of a new refrigerator
When deciding on repairs, it is necessary to take into account economic feasibility. Replacing a compressor includes the cost of the unit itself, the filter-drier, freon and the work of a technician. In total, this can amount to up to 60-70% of the cost of a new middle-class refrigerator.
If your refrigerator is more than 10-12 years old, replacing the “heart” may not be justified. Old heat exchangers (evaporator and condenser) also have their service life and may leak soon after replacing the motor. In this case, it is more logical to consider purchasing new equipment with a modern energy efficiency class.
However, if the refrigerator is premium or has a built-in design, replacing the compressor is often the only reasonable option. Modern inverter motors serve for a long time, and their failure usually means the end of the service life of the entire cooling system.
⚠️ Attention: When replacing the compressor, be sure to change the filter-drier. The old filter is already saturated with moisture and will not be able to efficiently clean the refrigerant, which will lead to repeated failure.
It is also worth considering that after soldering and replacing the motor, the system must be thoroughly vacuumed. Residual moisture or air in the circuit will lead to an increase in condensation pressure and overload of the new motor.
Prevention and extension of service life
In order to delay the moment of decompression and engine failure as much as possible, you must follow the operating rules. The main enemy of a compressor is overheating. Make sure that the refrigerator is at least 5-10 cm away from the wall, providing free air circulation around the condenser grille. Regularly cleaning dust from the back wall of the refrigerator will also work wonders. The layer of dust acts as a heat insulator, interfering with heat removal, which forces the motor to work with increased load. Wipe the grille with a dry cloth or use a vacuum cleaner once every six months. air circulation around the capacitor grid.
Regularly dusting the back of your refrigerator will also work wonders. The layer of dust acts as a heat insulator, interfering with heat removal, which forces the motor to work with increased load. Wipe the grille with a dry cloth or use a vacuum cleaner every six months.
- 🧹 Do not place the refrigerator close to the wall or in a niche without ventilation.
- 🌡️ Make sure that the room temperature does not exceed +30°C, unless this is indicated in the instructions.
- 🔌 Use a voltage stabilizer if your network has frequent power surges.
- 🚫 Do not load warm foods into the freezer, this creates an extra load on the system.
It is also important to monitor the condition of the door seals. If they allow heat to pass through, the compressor is forced to work almost non-stop, exhausting its service life at an accelerated pace. Checking the seals can be done using a sheet of paper: it must be tightly clamped by the door around the entire perimeter.
Compliance with these simple rules does not guarantee eternal operation, but significantly prolongs life refrigeration unit. Remember that prevention is always cheaper and easier than complex repairs with the replacement of expensive components.
What does it mean? if the compressor is hot but there is no cold?
This is a classic sign of loss of compression or blockage in the system. The motor runs, heats up from friction and gas compression, but due to wear on the valves or pistons, it does not create the necessary pressure for freon circulation. Diagnostics with a pressure gauge is required.
Is it possible to add freon if compression is lost?
No, adding freon will not help. If compression is lost due to mechanical wear, no amount of gas will make the engine run efficiently. The pressure will drop as soon as the engine stops.
How long does a compressor last in a refrigerator?
The average service life of modern compressors is 10-15 years. However, under favorable conditions (stable voltage, good ventilation, no overloads), they can work for 20 years or more.
Why can’t you turn on the refrigerator immediately after transportation?
During transportation, oil from the compressor could get into the circulation circuit. If you turn on the motor right away, it will run without lubrication (“dry”), which will lead to jamming and rapid decompression. You need to let the oil drain back into the crankcase (2-4 hours).
How to distinguish a leak from decompression?
When there is a leak, the pressure in the system drops to atmospheric pressure, and the engine may not start at all or run in short cycles. During decompression, the motor runs constantly, but there is no pressure in the system or it is not enough for cooling.