A sudden stop in the refrigerator often becomes an unpleasant surprise, especially when the ice in the freezer begins to melt and food begins to spoil. First of all, in such a situation, the owners of the units sin on the most expensive and important unit - compressor. Indeed, it is this motor that is responsible for circulating the refrigerant, and if it fails, the system stops cooling. However, there is no need to panic ahead of time, since the lack of cold can be caused by simpler reasons, such as a freon leak or a broken thermostat.
Before calling a technician or buying new equipment, it makes sense to carry out the initial inspection diagnostics on your own. This will allow you to understand the scale of the problem and save money if the repair turns out to be feasible for a home craftsman. Checking a motor-compressor requires care and compliance with safety precautions, but does not always require sophisticated equipment. In this article we will analyze all available methods for assessing the condition of the “heart” of your refrigerator.
It is important to understand that motor-compressor is a complex electromechanical unit that combines an electrical part and a mechanical pump. The malfunction may lie either in the motor windings or in the jamming of the piston group. Correct identification of the problem at the initial stage is the key to successful repair or an informed decision to replace the unit.
Primary visual and acoustic diagnostics
Any check begins with an external examination and analysis of the sounds that the household appliance produces. If the refrigerator is silent, although the indicators are on, or, on the contrary, it hums continuously without rest breaks, these are already the first alarm signals. In normal operation, the compressor turns on periodically, cools the chambers to the set temperature and turns off. If the cycle is broken, you need to listen to the nature of the noise.
The sound of a running motor should be smooth, monotonous and not too loud. The appearance of metallic knocking, grinding or sharp clicks often indicates mechanical wear of internal parts or problems with fastening. It is also worth paying attention to the temperature of the compressor housing itself, usually located in the lower rear part of the unit.
⚠️ Attention: Before touching the metal parts of the compressor or removing the protective casing, be sure to disconnect the refrigerator from the power supply! Electric shock can be fatal.
If the motor housing remains cold when touched by hand (after turning off!), although the refrigerator was running, this may indicate that the engine does not start at all. In the case when the motor is so hot that it is impossible to touch it, and at the same time it makes a humming sound, but does not start, the thermal protection is probably triggered due to overload or jamming.
Checking the start-up relay and thermostat
Before “sinning” on the motor itself, it is necessary to eliminate faults in its control circuit. Often the cause of failure is starting relay a small block that supplies the impulse to start the engine. If the relay is faulty, the voltage simply does not reach the windings, and the compressor is silent, even if it is fully operational.
To check the relay, it must be carefully removed from the contacts of the compressor. Visually inspect the housing for melting, cracks or burn marks. There may be a coil or posistor inside, which are also subject to wear. Lightly shaking the relay can help identify the destruction of internal elements - if a knock is heard, the part definitely requires replacement.
- 🔌 Contacts: Check the terminals for oxidation or carbon deposits, clean them if necessary.
- 🔊 Sound: If the relay is working properly, a clear sound should be heard at the moment of switching on click.
- 🌡️ Thermostat: Make sure that the temperature sensor is not stuck in the “off” position.
It is also worth checking thermostat. If it does not close the circuit when the temperature in the chamber rises, the compressor will not receive a start command. You can temporarily close the thermostat contacts (being careful!) to see if the engine will start. If after this procedure the refrigerator starts working, the problem lies in the sensor.
Using a multimeter to check the windings
The most accurate way to diagnose the electrical part of the engine is to test the windings using multimeter. This device will allow you to determine the integrity of the conductors and the absence of a short circuit. To carry out the test, you will need to remove the back cover, gain access to the contact group of the compressor and remove the start relay.
The contact group usually has three terminals. You need to switch the multimeter to resistance measurement mode (Ohms) and measure the resistance between each pair of contacts one by one. The measurement results will help to understand the condition of the windings: starting, working and general.
| Pair of contacts | Normal resistance | Possible malfunction |
|---|---|---|
| Working - General | 10–30 Ohm | Open or short circuit |
| Starting - General | 20–50 Ohm | Open or short circuit |
| Working - Starting | The sum of the two is higher | Incorrect data |
| Any - Case | Infinity (∞) | Breakdown on the case |
If the device shows infinity (one in the leading discharge), which means in the winding break. If the resistance is close to zero, it happened short circuit. In both cases, the compressor is considered faulty and requires replacement. Pay special attention to checking for breakdown of the housing: one probe is placed on the cleaned metal of the housing, the other on the contacts. There should only be infinite resistance.
Why is the resistance of the starting winding higher?
The starting winding is wound with a thinner wire and has more turns to create the necessary magnetic shift for rotor start.
Testing the compressor directly (bypass)
If the electrical part rings normally, but the engine does not start, you can try to apply voltage directly, bypassing the refrigerator control system. This method allows you to understand whether it is motor able to rotate at all under load. For such a test, you will need a special starting device or a working relay from another compressor, as well as a 220V power source.
The essence of the method is to simulate the operation of a standard circuit. A constant voltage is supplied to the working winding, and a pulse is supplied to the starting winding through a capacitor or relay only at the moment of start. This is a risky procedure that requires a steady hand and an understanding of the principles of electrical engineering.
☑️ Safe start of the compressor
Upon a successful start, you will hear a characteristic hum and feel how air begins to forcefully come out of the output tube. If the motor hums, but the shaft does not rotate, and after a few seconds the protection (click) is activated, there is a mechanical part. Attempts to wedge such motors at home are rarely successful and often lead to final failure. wedging mechanical part. Attempts to wedge such motors at home are rarely successful and often lead to final failure.
⚠️ Attention: When connecting directly, do not hold the compressor output tubes with your fingers! The pressure of the forced air can damage the skin or introduce dirt into the system.
Analysis of pressure and performance
Electrical service does not guarantee that the compressor is pumping freon. Mechanical wear of valves or piston group can lead to the fact that the motor works, but does not create the necessary pressure in the system. You can check this by connecting the pressure manifold to the service fitting, if provided by the design, or by carefully tearing the capillary tube (which requires subsequent refilling).
A simple “folk” method is to evaluate the force of the air stream at the outlet of the discharge tube when the compressor is operating. If a finger brought to the hole does not feel a confident, powerful pressure, but only a weak blow, then the compressor “does not hold” the pressure. This often happens in older models, where the gaps between parts have increased due to wear.
- 💨 Jet force: The air should escape with noticeable pressure.
- 🔥 Heating: The outlet tube should heat up quickly during operation.
- 🛢️ Oil: A lot of oil should not fly out with the air.
It is important to note that modern inverter compressors Daikin, LG or Samsung it is more difficult to diagnose in this way, since they do not start without a control controller. To check them, special test equipment is required that sends signals to the control board.
Typical symptoms and causes of malfunctions
Systematization of symptoms helps to quickly diagnose diagnosis. Different manifestations of compressor problems indicate different internal defects. Understanding these differences allows you to avoid unnecessary diagnostic costs.
For example, if the motor starts, runs for a few seconds and turns off with a click, most likely the problem is a thermal relay or an interturn short circuit that causes rapid overheating. If the refrigerator operates continuously without turning off, and the temperature in the chambers does not drop below +10 degrees, this may be a sign of a loss of performance or a refrigerant leak, rather than a breakdown of the motor itself.
Below is a table of the main symptoms and probable causes:
| Symptom | Probable cause | Difficulty of repair |
|---|---|---|
| Silence, no reaction | Open circuit, burnt relay | Low |
| Humming, clicks, does not start | Stuck, winding breakdown | High |
| Works without stopping | Freon leak, compressor wear | Average |
| Strong vibration and noise | Destruction of the suspension, wear of bearings | High |
It is worth remembering that in some cases the “treatment” will not be repair, but replacement. Modern hermetic compressors are not designed to be opened and restored in domestic conditions. An attempt to disassemble such a unit is almost guaranteed to lead to its final failure.
Frequently asked questions (FAQ)
Is it possible to replace the compressor on a refrigerator yourself?
Theoretically, yes, if you have the skills to work with tools and access to a vacuum pump and a filling station equipment. However, the process requires sealing the system, evacuation and precise charging of freon. Without special equipment, a high-quality replacement is impossible.
How much does a new compressor for a refrigerator cost?
The price depends on the model and manufacturer. The cost of the unit itself can vary from 3,000 to 10,000 rubles and more. Together with the work of the master and materials (freon, solder), the final cost of the repair often makes up a significant part of the cost of a new refrigerator.
Why is the compressor hot to the touch?
In operating condition, the compressor heats up to 60–90 degrees Celsius, which is the norm. It is cooled by oil circulation and external airflow. If the temperature is critically high and there is a burning smell, this is a sign of overload or malfunction.
What is better: repairing an old compressor or buying a new one?
Repairing an old compressor (rewinding, replacing valves) under service conditions is possible, but the service life of such a unit will be unpredictable. In most cases, it is safer and more economical to install a new unit or a high-quality analogue.
How to extend the life of a compressor?
Do not place the refrigerator close to the wall to ensure ventilation. Defrost the chamber regularly, do not load warm food and keep the condenser at the back clean. These simple measures reduce the load on the motor.