Sudden silence in the kitchen, where the unit usually hummed, or, conversely, startup attempts that end with a click and shutdown, always cause panic. Compressor failure is critical a situation leading to rapid spoilage of food and increased temperature in the chambers. Many owners immediately call a technician, but often the problem can be diagnosed independently if you know the main signs of a malfunction.
Understanding how it works refrigeration circuitwill help you not only save on diagnostics, but also avoid buying new equipment. In most cases, the “motor” (as the compressor is called in everyday life) stops working not due to fatal wear, but due to the failure of auxiliary elements or power surges. However, there are also more serious breakdowns that require the intervention of a professional.
In this article we will examine in detail all possible causes, from a banal lack of electricity to a complex interturn short circuit. You will learn how to distinguish a malfunction of the engine itself from problems with the control circuit and whether it is worth trying to start the unit yourself. The most common cause of startup failure (about 60% of cases) is a malfunction of the start-up relay or thermostat, and not the compressor itself.
Primary diagnostics: electricity and network
Before opening the technical compartment and sinning with complex mechanics, it is necessary to exclude the most obvious factors. Users often forget that refrigeration equipment is sensitive to the quality of the supplied voltage. If there are constant surges in the network or, conversely, chronically low voltage, the motor may simply not start, protecting itself from overload.
Check whether the light inside the chamber is on when the door is opened. If there is no light, the problem may be with the outlet or surge protector. Try plugging in another powerful appliance, such as a hair dryer or kettle, into the same outlet to make sure there is current. Electronic control modules Modern models can block the compressor from starting if the power supply is unstable.
⚠️ Attention: If you hear the hum of the motor, but it does not start, immediately disconnect the device from the network. Long-term operation in this mode (humming without shaft rotation) will lead to overheating of the windings and guaranteed engine combustion.
It is also worth paying attention to the length and condition of the power cord. Visually inspect it for kinks, melts, or signs of rodents. Sometimes the problem lies in poor contact of the plug with the socket, which causes a voltage drop precisely at the moment of start, when current consumption is maximum.
Faults in the starting protection relay
One of the key parts that ensures the engine starts is the starting relay. It is this small element that supplies an impulse to the starting winding, allowing the rotor to spin. If starting relay fails, the compressor will only hum or click quietly, but the shaft will not rotate.
In older models, electromagnetic relays are used, in newer ones - posistor (thermal). The posistor loses its properties over time and stops passing current to the starting winding at the right time. Replacing this part is an inexpensive procedure and can often be done with your own hands if you have the skills to work with a multimeter.
How to test a relay with a multimeter?
To check a posistor relay, you need to ring it in a cold state. The resistance should be between 10-30 ohms. If the device shows infinity or zero, the part is faulty. Electromagnetic relays are checked for sticking of contacts and integrity of the coil.
Symptoms of a relay malfunction are often confused with a breakdown of the motor itself. However, if when you tap the relay (carefully, with the handle of a screwdriver while the device is on), the motor tries to start, then the problem is in the contacts or the switching mechanism. In such cases mechanical wear contacts do not allow closing the circuit.
Problems with the thermostat and sensors
The compressor power circuit passes through a thermostat (thermostat) or an electronic temperature sensor. If this element “does not see” the temperature increase in the chamber, it simply will not give the command to start the motor. In mechanical models thermostat it is a switch that opens the contacts when the set temperature is reached.
It often happens that the capillary tube of the thermostat moves or bursts, causing the filler gas to evaporate. As a result, the contacts remain open forever. You can check this by shorting the two wires going to the thermostat directly (only for a short time for diagnostic purposes!). If the motor starts working, the thermostat is to blame.
In refrigerators with a system No Frost and electronic control, air sensors are responsible for the temperature. Their malfunction often leads to erroneous readings for the control module. The control unit, receiving a signal that it is already cold in the chamber (or, conversely, an open circuit signal), blocks the start of the compressor to avoid defrosting or overload.
Overload protection and thermal relay
A thermal protection relay is often installed on the compressor housing or in conjunction with the starting relay. Its task is to break the power circuit if the current consumption exceeds the norm or if the motor housing has heated up to a critical temperature. If thermal protection triggered, the motor will not turn on until it has completely cooled down.
Frequent activation of the protection may indicate problems with ventilation. Make sure the condenser (grid at the back of the refrigerator) is not clogged with dust or pet hair. Dirt on the radiator impairs heat transfer, the refrigerant does not condense properly, the pressure in the system increases, and it becomes harder for the motor to work, which causes the protection to trip.
Also, the cause of false alarms can be the aging of the bimetallic plate inside the protection relay itself. Over time, it becomes deformed and begins to open the circuit at lower temperatures than expected. Visually, such a part may look intact, but ceases to perform its functions.
| Symptom | Probable cause | Characteristic sound |
|---|---|---|
| Silent, no light | No power, faulty socket | Complete silence |
| Buzzing for 3-5 seconds, click, silence | Compressor jammed or relay burned out | Buzzing, then clicking |
| Clicks, but does not buzz | Faulty starting relay | Frequent clicks |
| Works for 1 minute, turns off | Thermal protection is triggered | Humming, then silence |
Mechanical wedge of the compressor
The most unpleasant situation is when the electrical part is working, the voltage comes, the relays work, but motor-compressor physically cannot turn the shaft. This phenomenon is called "wedge". It occurs due to oil burnout, moisture entering the system or wear of the rubbing pairs of the piston group.
In this state, the engine consumes a huge starting current, which instantly triggers the protection or hums until the winding burns out. Experienced craftsmen sometimes try to “unjam” the unit by applying increased voltage or using a special transformer, but this is a temporary measure.
⚠️ Attention: Attempts to start a jammed compressor using capacitors or supplying 380 Volts are dangerous. This can lead to an explosion of the compressor cylinder or a fire due to the ignition of oil and freon.
If you hear a powerful blow when trying to start, and then a buzzing sound, most likely the piston is stuck in the cylinder. In modern hermetic compressors, mechanical repairs are not economically feasible. A complete replacement of the unit is required, which is comparable to the cost of a new refrigerator.
Electrical malfunctions of the windings
Inside the motor there are two main windings: starting and working. During power surges or overheating, winding break or interturn short circuitmay occur. In the first case, the circuit breaks and the current simply does not flow. In the second, the resistance drops, the current increases, and the protection is triggered.
Diagnostics of breaks and short circuits is carried out using a multimeter. It is necessary to measure the resistance between the contacts on the compressor block. Normal resistance values are usually in the range of 10 to 30 ohms for the operating winding and slightly higher for the starting winding. If the device shows infinity - an open circuit, if close to zero - a short circuit.
☑️ Compressor diagnostics
Particular attention should be paid breakdown to the housing. If one of the winding contacts shorts to a copper tube or motor housing, this will not only damage the equipment, but can also be life-threatening if it touches metal parts of the refrigerator. In this case, operation is strictly prohibited.
Malfunctions of the control module (for inverter models)
In modern refrigerators with an inverter type of engine, the start and shaft rotation speed are regulated by an electronic module. If inverter unit is faulty, it will not generate the necessary impulses to start. Such systems are more difficult to diagnose, as they require special equipment to check the signals.
Often the control module fails due to voltage surges in the network or moisture ingress (for example, during defrosting, when water flows into the technical compartment). Visually, swollen capacitors or traces of burning may be visible on the board, but often the defect is hidden inside the microcircuits.
Repair of modules is often possible, but requires the qualifications of a radio engineer. The owner should only check the integrity of the wires going from the board to the compressor and the absence of oxides on the connectors. Oxidized contacts can create a high contact resistance that prevents normal operation.
Frequently asked questions (FAQ)
Is it possible to temporarily start a refrigerator without a relay?
Theoretically, you can start the motor by applying voltage directly to the working winding, but doing this is extremely dangerous and is not recommended. Without a starting winding and relay, the motor may not gain momentum, burn out, or cause a fire. This is an emergency measure for technicians to check the compressor, and not a solution for operation.
Why does the refrigerator click but does not turn on?
The click usually comes from the start relay or thermal protection. This means that voltage is coming to the motor, there is an attempt to start, but something is preventing rotation. Most often, the culprit is a stuck relay, a jammed compressor, or a break in the starting winding.
How much does it cost to replace a compressor?
The cost consists of the price of a new unit and replacement work (including evacuation of the system and refilling with freon). Depending on the model of the refrigerator and the region, the price can vary from 5 to 15 thousand rubles and higher.
Can the motor burn out due to long periods of inactivity?
Yes, if the refrigerator stood in a damp room for a long time, condensation could form inside the windings, causing corrosion or a short circuit. The oil could also thicken. Before turning it on after a long period of inactivity, it is recommended to keep the equipment in a warm, dry room for several days.