The situation when the refrigerator turns on and immediately turns offis one of the most stressful for the owner of household appliances. You open the door to get groceries and notice that it is warm inside, and the unit itself is silent or makes short humming sounds that stop after a few seconds. This is a classic symptom of a protective operation of the system, which is designed to prevent the final failure of expensive equipment.
Cyclic on and off, often called “clocking,” indicates that the compressor motor is trying to start, but encounters resistance or overload. As a result, thermal relay or the protective mechanism is triggered, breaking the power circuit. If you ignore this signal, you can wait until the motor windings burn out completely, which will require replacing the entire compressor.
In this article we will analyze in detail the main reasons for this behavior of the unit, self-diagnosis methods and action algorithms that will help you understand whether you need an urgent call to a technician or the problem can be solved yourself. It is important to understand that the exact reason depends on the model of your refrigerator, be it Atlant, Indesit or LG.
Problems with the start relay and electrical system
The most common reason why the refrigerator turns on for a couple of seconds and turns off is a faulty start relay. This small element is responsible for supplying voltage to the starting winding of the engine at the moment of start. If the relay is “stuck” or burned out, the compressor hums, but cannot start, followed by a click and shutdown.
Often owners confuse the symptoms, thinking that the problem is in the motor, although replacing the relay is much cheaper and faster. In older models, relays can be mechanical, in modern ones they can be electronic, but the principle of protection remains the same. When you try to start, the current increases sharply, and if the rotor does not start rotating, the thermal protection opens the contacts.
⚠️ Attention: Before any manipulations with electrical components, be sure to unplug the refrigerator! A voltage of 220 volts is dangerous to life, even if the unit has just been running.
To check the relay, you must remove the back cover of the refrigerator at the bottom where the compressor is located. Carefully remove the plastic casing from the relay and inspect it for melting, cracks, or a burning smell. If there are no visual defects, you can try to gently shake the relay near your ear: if something rattles inside, it means the mechanism is destroyed.
How to check the relay with a multimeter?
To check, you will need a multimeter in dial mode. Ring the relay contacts: if the device shows infinite resistance or, conversely, a short circuit where there should not be one, the part is faulty. Also check the resistance of the starting and operating windings of the compressor itself through the relay contacts.
Malfunctions of the motor-compressor
If everything is in order with the relay, the problem may lie in the very heart of the refrigerator - motor-compressor. The engine may be electrically correct, but have mechanical defects. For example, jamming of the piston group due to exhaustion of service life or metal shavings entering the system.
In this case, the motor shaft cannot turn, the current in the windings increases to critical values, and the thermal protection emergency turns off the power. A characteristic sign of such a breakdown is a strong, strained hum for 3-5 seconds before the shutdown click. This is the sound of the engine operating “at the limit.”
Diagnostics of a compressor requires special skills and tools. The technician connects the unit directly, bypassing the standard automatics of the refrigerator, in order to evaluate the starting current and the ability of the engine to develop speed. If the motor is “heavy” and does not start even with a direct connection, it needs to be replaced.
There is another rare but possible reason - an interturn short circuit in the electric motor windings. In this case, the resistance of the windings drops, the current increases, and the protection is triggered instantly. This can only be checked by measuring the resistance of the windings with a multimeter and comparing the readings with these values for a specific model.
Failures in the operation of the thermostat and sensors
In modern refrigerators with a system No Frost and electronic control, it is not the mechanical thermostat that is responsible for starting the compressor, but an electronic control module that receives data from temperature sensors. If the evaporator or air damper sensor transmits incorrect data, the “brain” of the refrigerator may behave incorrectly.
For example, if the sensor “thinks” that the temperature in the chamber has already reached the required minimum, it will give a command to stop the compressor immediately after it is turned on. Or, in the event of a malfunction, the control module can send short pulses to start, which are perceived as cyclic on-off.
For diagnostics, you need to enter the service mode of the refrigerator (the combination of buttons depends on the brand, for example, holding the freeze and temperature buttons for a long time) and look at the error codes or current sensor readings. discrepancies in the readings will indicate a faulty element.
Problems with wiring and contacts
Do not discount trivial problems with the power supply. A loose electrical outlet, a broken power cord, or corroded terminals inside the refrigerator can cause a voltage drop. The motor does not have enough power to start, it hums, heats up and turns off.
Particular attention should be paid to the place where the cable enters the refrigerator body. Frequent movements or vibrations can cause the wire to break inside the insulation. At the moment of startup, when the current consumption is maximum, a voltage drop occurs at the site of the damage, and the compressor stalls.
Also check the contacts on the starting relay itself and the compressor terminals. Sometimes they oxidize or weaken, creating additional resistance. Stripping the contacts and tightly fitting the terminals often solves the problem of "floating" starting.
The effect of low voltage in the network
In private homes or old areas of cities, the problem of low voltage in the electrical network is often encountered. If the voltage drops below 190-200 Volts, the engine power may not be enough to overcome the freon resistance and start the rotor.
The compressor tries to start, the current increases, but rotation does not occur. The thermal relay detects the current overload and turns off the unit. After some time, the relay cools down and tries to start the motor again, and the cycle repeats.
To solve this problem, you need to measure the voltage in the outlet when you try to start the refrigerator. If the voltage is really low, installing a voltage stabilizer will help. This will protect not only the refrigerator, but also other sensitive electronics in the house.
⚠️ Attention: Long-term operation of the compressor in the “hum” mode without starting at low voltage can lead to overheating and melting of the starting winding. Do not leave a faulty device connected to the network for a long time.
Diagnostics and table of symptoms
To systematize troubleshooting, it is convenient to use the table of symptoms. It will help you narrow down your search before calling a technician or purchasing spare parts. Remember that an accurate diagnosis can only be made by a specialist with equipment.
Below is a table linking the observed symptoms with the most likely causes. Pay attention to the duration of operation before shutting down and the accompanying sounds.
| Symptom | Probable cause | Difficulty of repair |
|---|---|---|
| Buzzing for 3-5 seconds, clicking, silence | The starting relay is faulty or the compressor is jammed | Medium / High |
| It turns on, runs for 10-20 seconds, turns off | Overheating of the compressor, problems with ventilation | Low |
| Clicks, but does not buzz | Open circuit, malfunction of thermostat or module | Medium |
| Buzzes constantly, does not turn off | Freon leak, door leaks | High |
| The automatic switch in the control panel is triggered | Short circuit in the wiring or motor | High |
If you find that your case falls into the "High" complexity category, especially when it comes to replacing the compressor or finding a refrigerant leak, it is better not to take risks. Self-repair of the cooling system requires evacuation and charging with freon, which is impossible without professional equipment.
☑️ Diagnostics before calling a technician
Frequently asked questions (FAQ)
Is it possible to operate the refrigerator if it turns on and turns off immediately?
Strongly not recommended. This mode of operation leads to rapid overheating of the motor windings and can cause a fire or permanent failure of the compressor. Products will also deteriorate due to lack of cold.
How much does it cost to replace a starting relay?
The cost of the relay itself is usually low (from 500 to 2000 rubles depending on the model), but the work of a technician to diagnose and replace it can cost more, especially if a visit is required. In some models, the relay is assembled with a terminal block.
Why does the refrigerator click but does not start?
The click is the sound of the thermal relay contacts opening or the bimetallic plate triggering. This means that the current in the circuit exceeds the norm, but the engine does not start. Most often, the starting relay or the compressor itself is to blame.
How long does it take for a thermal relay to cool down?
Usually, a thermal relay takes 15 to 40 minutes to completely cool down and return the contacts to their original state. If you try to turn on the refrigerator immediately after turning it off, it may not start.