Sudden silence in the kitchen or, conversely, a hum that does not stop for a minute, often signal problems with the “heart” of the refrigeration system. Compressor responsible for the circulation of the refrigerant, and it is its serviceability that determines whether your products will be fresh or spoiled. Self-diagnosis of this unit allows you to save time on calling a technician and understand whether it is worth undertaking expensive repairs at all.
Before grabbing the tools, it is necessary to conduct an initial assessment of the situation without disassembling the unit. Refrigerators different brands, be it Indesit, Atlant or LG, have similar principles of operation, but may differ in the nuances of fastening and connection. Your task at this stage is to determine whether the motor is showing signs of life or whether it is completely dead.
Listen carefully to the sounds that the household appliance makes at the moment when the cooling cycle should turn on. If you hear the characteristic click of the start relay, followed by a hum that lasts a few seconds, and then silence, this is a sure sign that motor-compressor tries to start but cannot. This situation often indicates a jammed mechanism or problems with the electrical part.
However, if the unit is silent and the light inside is on, the problem may lie in the lack of voltage at the terminals or a burnt winding. Never attempt to test a sealed unit if it is hot to the touch - allow it to cool for at least 30-40 minutes before starting work. This safety rule is critically important, since working with hot equipment may result in burns or false instrument readings.
Visual diagnostics and primary signs of malfunction
The first step in diagnosis is a thorough external examination. You don't need sophisticated equipment to spot obvious defects. Often malfunction it reveals itself visually: blackening of the tubes, traces of oil on the floor, or swelling of the compressor housing itself. If you notice oil stains under the unit, this may indicate depressurization of the system, which makes further operation impossible without professional intervention.
Pay attention to the temperature of the motor housing. If the refrigerator does not cool, but the compressor itself is so hot that it is impossible to touch it, this is an alarming symptom. During normal operation, the knot should be warm, but not scalding. Excessive heating often indicates that thermal relay does not open the circuit, or the engine is running dry due to a freon leak.
⚠️ Attention: If you see sparking in the area of the contact group or smell burnt wiring, immediately turn off refrigerator from the mains. Further diagnostics without the skills of an electrician can be life-threatening.
It is also worth checking the condition of the start relay, which is mounted on the side of the compressor housing. This is a small plastic box with a trigger mechanism inside. If, when you shake the removed relay, you hear a ringing sound, like from broken glass, it means that the internal contact group is destroyed. In this case, the motor itself may be in good working order, but it will not be able to start.
Checking the integrity of the windings with a multimeter
The most accurate way to check the electrical part is to test the windings using multimeter. This device allows you to determine whether there is an open circuit or short circuit. To carry out the procedure, you will have to remove the protective casing on the back wall of the refrigerator and disconnect the start relay to gain access to the three contacts on the motor housing.
Set the multimeter to resistance measurement mode (usually indicated as 200 ohms or 2 kohms). You need to check the resistance between every two pins out of the three available. Normal values for a working engine range from 20 to 140 Ohms, depending on the model and power. If the device shows one or infinity, it means that there has been a break in the winding break.
- 🔌 Check the resistance between the top and left contacts - this is the working winding.
- ⚡ Measure the resistance between the top and right contacts - this is the starting winding.
- 🔗 Measure the resistance between the two lower contacts - the sum of the resistances should be equal to the resistance of the working winding.
Pay special attention to checking for breakdown on the case. Switch the multimeter to dialing mode (with a beep). Press one probe to any motor contact, and the second to a place on the metal body of the compressor that has been cleared of paint. If the device beeps, it means that the insulation has been broken and has occurred short circuit on the housing. It is strictly prohibited to operate such a unit.
Diagnostics of the starting relay and thermostat
Often the reason that the refrigerator has stopped freezing is not the motor itself, but the auxiliary elements. Start relay is responsible for sending an impulse to the starting winding, allowing the rotor to start rotating. If this element fails, the compressor either hums and does not start, or is silent. Remove the relay and inspect it for cracks, carbon deposits or melted contacts.
Thermostat is another candidate for inspection. It is he who gives the command to turn on the compressor when the temperature in the chamber rises. To check it, you can close the two contacts coming from it directly (after disconnecting the refrigerator from the network!). If, after connecting to the network, the motor starts working, then the problem lies in thermostat, and not in the motor
When diagnosing the relay, it is important to take into account its type. Modern models often use posistor relays, which do not have moving contacts and are tested only for resistance. Old models with electromagnetic coils can be checked visually: the coil should not have signs of overheating, and the contacts should not have carbon deposits.
| Element | Symptom of serviceability | Symptom of malfunction | Check method |
|---|---|---|---|
| Start relay | Entire body, contacts without carbon deposits | Cracks, burning smell, no click | Visual inspection, continuity of contacts |
| Thermoregulator | Clicks when temperature changes | Does not close the circuit when cooling | Closing contacts directly |
| Compressor (windings) | Resistance 20-140 Ohm | Infinity or zero Ohm | Measurement with a multimeter |
| Breakdown to the body | No signal when dialing | Multimeter sound signal | Contact-housing test |
Checking the pressure and tightness of the system
If the electrical part is in order, but no cold is produced, the problem may lie in the mechanical part or a refrigerant leak. To accurately diagnose pressure, a special tool is required - pressure station. By connecting it to the process pipe (usually it is sealed, but sometimes accessible), you can see the real pressure in the system.
In a properly functioning refrigerator, the pressure on the suction side should be negative (vacuum), and on the discharge side - high. If the pressure gauge shows zero or the pressure drops quickly after the compressor stops, then there is freon leakin the system. Without special equipment and soldering skills, it is almost impossible to fix this problem yourself.
⚠️ Attention: Freon used in refrigerators can be dangerous if inhaled in high concentrations, and it is also highly flammable (in the case of isobutane). Do not release gas indoors.
It is also worth checking the filter drier. If it is clogged or frozen (covered with frost), the circulation of the refrigerant is disrupted. This often happens when moisture gets into the system. This can be visually determined by the swelling of the filter or the characteristic whistle emanating from it when the motor is running.
Is it possible to refill the refrigerator yourself?
Theoretically, it is possible if you have the equipment and skills. However, this requires evacuating the system, accurately dosing the refrigerant, and using the correct oil. An error in the amount of gas will lead to breakdown of the compressor.
Analysis of noise and vibration during operation
The sound of the refrigerator operating can tell a lot about its technical condition. A quiet, uniform hum is considered normal. If you hear a metallic clanging, knocking or shrill whistle, this indicates mechanical wear of the internal parts piston group.
Strong vibration of the compressor housing often indicates that the shock-absorbing springs on which the motor is suspended inside the casing have worn out. In this case, the engine begins to hit the walls, which over time can lead to pipe breakage. Vibration can also be caused by improper installation of the refrigerator itself - check the adjusting feet.
- 🔊 Loud knocking at startup - wear of the connecting rod and piston group.
- 🌬️ Hissing or whistling - freon leak or capillary tube clogged.
- 🔨 Metallic clanging - destruction of valves or entry of a foreign object.
If the compressor operates intermittently, starting and stopping at short intervals, this phenomenon is called “clocking”. It is extremely harmful to the engine and is often caused by a malfunction of the starting relay or thermal protective device, which is triggered prematurely due to overheating.
☑️ Noise diagnostics
Replacement or repair: what to choose?
When the diagnostics are completed and the diagnosis is made, the question arises about the feasibility of repairs. If the winding burns out or there is a breakdown on the housing, replacing the compressor is the only viable solution. Repairing the sealed unit itself at home is impossible and economically unfeasible, since it requires rewinding the motor in the factory.
If the problem lies in the start relay or thermostat, replacing these components will cost much less and is within the capabilities of a home craftsman. It is important to choose an analogue with exactly the same characteristics, otherwise the new compressor may quickly fail or not start at all.
It is worth considering the age of the refrigerator. If the equipment is more than 10-12 years old and the motor-compressor itself needs to be replaced, it is often more profitable to buy a new unit. The costs of a new compressor, its installation, evacuation of the system and refilling with freon can amount to up to 50-70% of the cost of a new refrigerator.
⚠️ Attention: When installing a new compressor, be sure to change the filter drier. The old filter is already saturated with moisture and can quickly clog the new system, leading to repeated failure.
Frequently asked questions (FAQ)
Is it possible to start a compressor without a relay?
Technically, you can start the motor by applying voltage directly to the working and starting windings, but this must be done extremely carefully and for a short time. However, for constant operation the relay is necessary, since it automatically turns off the starting winding after a set of revolutions. Working without a relay will lead to rapid combustion of the starting winding.
Why is the compressor hot, but not cold?
This is a classic sign of a freon leak or a blockage in the system. The motor runs, trying to pump the refrigerant, but due to the lack of substance or obstruction in the tubes, heat exchange does not occur. Also, the cause may be a malfunction of the valves inside the compressor, when it does not create the required pressure.
What current does a working compressor consume?
Depending on the power and model, the operating current of a typical household compressor ranges from 0.5 to 1.5 Amperes. At the moment of startup, the current may briefly jump to 3-5 Amperes. This can be measured using current clamps, putting them on one of the power wires.
Is it worth changing the compressor on an old refrigerator?
The decision depends on the cost of repairs and the condition of the rest of the equipment. If the refrigerator is old, it may have worn seals, damaged internal plastic, or corrosion. In such cases, replacing the “heart” of the system may not extend the life of the unit for long. It is economically justified to repair equipment up to 7-8 years old.