The situation when the refrigerator turns on and turns off after a few seconds is a classic sign of an emergency operation of the cooling system’s protective mechanisms. The compressor tries to start, makes a characteristic click or hum, but cannot gain speed, after which the thermal relay opens the circuit to prevent overheating of the windings. This behavior of the equipment, known as “failure to start,” indicates a serious malfunction of the electrical part or mechanical jamming of the unit.
Ignoring this problem can lead to the complete failure of an expensive component - the compressor, which in modern models is often integrated with the control system. The owner can hear periodic clicks coming from behind the unit, but the motor itself will not work. In rare cases, the cause is a simple power surge, but most often it lies in the wear of internal components, such as a starting relay or capacitor.
Further operation of the device in this mode is strictly prohibited, since each unsuccessful start heats the motor windings, destroying the insulation. If you notice that your Bosch, Indesit or any other brand behaves in a similar way, you must immediately disconnect the device from the network and carry out initial diagnostics. Understanding the nature of the sound and the duration of the switching cycle will help you accurately determine the unit that requires replacement.
⚠️ Attention: If, when trying to start, you smell a burning smell or see sparking in the area of the electrical connectors, further self-diagnosis without turning off the power is life-threatening.
Main signs of a faulty start relay
The most likely reason that the refrigerator clicks and does not start is a failure of the start relay. This small component is responsible for sending a starting pulse to the second winding of the motor, allowing the rotor to start rotating. If the relay is “stuck” or its contacts are burnt, no current flows to the starting winding, and the compressor simply hums, trying to move until the thermal relay turns off the power.
In modern inverter models, the role of the relay is played by an electronic board, but in classic units a mechanical or posistor element is used. Mechanical relays often fail due to vibrations and temperature changes, causing a characteristic metallic clanging sound when trying to start. The posistor options burn out silently, simply by opening the circuit, which can be visually determined only by the blackening of the housing or the absence of a characteristic crackling sound.
To check the relay, you need to get to the compressor located in the lower rear part of the refrigerator. After removing the protective casing, you will see a box placed on the compressor rod. Having carefully disconnected the wires and removed the relay, you can shake it near your ear: if you hear the ringing of scattered parts inside, the element definitely needs to be replaced. This is one of the most common and easily removable reasons why the refrigerator turns on and immediately turns off.
How to replace the start relay yourself
To replace, remove the old relay, remembering the orientation of the contacts, and install a new one, strictly observing the markings (UP/DOWN). Make sure that it sits tightly on the compressor rod, otherwise vibration will quickly destroy the contacts.
Problems with the compressor: jamming and windings
If replacing the start relay did not help and the engine still does not start, the problem may lie in the very heart of the refrigeration machine. Compressor jamming is a mechanical malfunction in which the piston group or spiral mechanism loses mobility due to exhaustion, lack of lubrication or foreign particles entering the freon circuit. In this case, the motor tries to turn over, emits a powerful low-frequency hum, but physically cannot overcome the resistance.
Another option is an interturn short circuit in the electric motor windings. In this case, the resistance of the windings drops, the current increases to critical values, and the thermal protection is instantly triggered, opening the circuit. You can check the integrity of the windings using a multimeter in resistance measurement mode. Normal indicators for different pairs of contacts (working-starting, working-housing, starting-housing) must correspond to the technical characteristics of a particular model, for example Atlant or Liebherr.
There is a method of “wedging” the compressor by applying increased voltage directly to the working winding, bypassing the starting winding. However, this method is extremely risky and requires professional skills, since you can completely finish off the unit or get an electric shock. If the compressor is really jammed, the only correct solution is to replace it along with the filter drier and evacuate the system.
Faults of the starting capacitor
In the circuits of some refrigerators, especially in models with powerful compressors, a starting capacitor is used. This element accumulates charge and releases it at the moment of startup, creating the necessary phase shift for rotor rotation. If the capacitor has lost capacity or is swollen, there is not enough starting torque and the engine stops without gaining speed. Externally, a faulty capacitor often looks swollen or has traces of electrolyte on the body.
Diagnostics of the capacitor is carried out visually and using a capacitance measuring device. Even if there are no visual defects, a loss of rated capacity of 20% or more already leads to unstable operation. In such cases, the refrigerator may not start the first time or work intermittently until the protection turns off the power again. Replacing a capacitor is an inexpensive procedure, but requires precise selection of parameters (μF and Volt).
It is important to note that in some modern control systems, capacitors may be integrated into the board or absent altogether, since their function is performed by electronic keys. Therefore, before looking for a capacitor, it is worth studying the electrical diagram of your device. The absence of this element where it should be, or its obvious deformation is a sure sign of a problem.
Low voltage in the power supply
Often the reason that the refrigerator turns on and immediately turns offis not the equipment, but the quality of the power supply in the house. Compressors are sensitive to voltage changes: if it drops below 190-200 Volts, the starting torque may not be enough to overcome the pressure in the system. The engine begins to hum, consumes increased current and heats up quickly, which triggers the thermal relay.
This problem is especially common in country houses, holiday villages or during peak network load hours (evening time). In such conditions, equipment operates at the limit of its capabilities, which shortens its service life. To protect expensive equipment, it is recommended to use a voltage stabilizer, which will ensure a smooth start and operation within a given range.
You can check the voltage version by connecting the refrigerator to another outlet or using a voltmeter. If surges are confirmed, installing a stabilizer or voltage control relay will become a prerequisite for further operation. Ignoring this requirement may lead to burnout of the compressor windings, the repair of which is not economically feasible.
⚠️ Attention: The use of cheap Chinese stabilizers with low speed may not save equipment from sudden surges. Choose devices with power reserves and overload protection.
Diagnostics of the thermostat and sensors
Although less common, a faulty thermostat or electronic temperature sensor can cause cyclic on-off switching. If the thermostat contacts are burnt or “stuck” in the open position, the compressor power circuit does not close completely, or closes for a split second. In electronic systems, a sensor failure can send a false signal that the temperature has been reached, forcing the controller to stop the motor immediately after starting.
Mechanical thermostats are characterized by a test method by closing the contacts directly. If, when the wires are shorted (bypassing the regulator itself), the compressor starts and operates normally, then the problem is in the thermostat. In electronic control units Samsung or LG diagnosis is carried out through a test mode or by measuring the resistance of the sensor at different temperatures.
It is also worth checking the integrity of the wiring going to the thermostat. A broken wire or oxidized contact can create the effect of an intermittent connection, simulating the breakdown of more complex components. Visual inspection of wires for melting or mechanical damage often helps to find the cause quickly and cost-effectively.
☑️ Primary diagnostics of the refrigerator
Table: Symptoms and probable causes
To simplify diagnostics, below is a table comparing the sound signs and behavior of equipment with the most likely malfunctions. This will help narrow down your search before calling a technician or purchasing spare parts.
| Symptom | Sound | Probable cause | Difficulty of repair |
|---|---|---|---|
| Click after 3-5 sec | Single click, silence | Faulty start relay | Low |
| Humming and shutdown | Low hum, then click | Compressor jammed | High |
| Frequent clicks | Series of rapid clicks | Problems with the capacitor | Average |
| Jerky work | Unstable hum | Low voltage in the network | Low (stabilizer needed) |
| Silence after switch on | No engine sounds | The thermostat is faulty | Low |
When a specialist call is necessary
Despite the possibility of self-diagnosis of some components, there are situations when professional intervention is inevitable. If the problem lies in a sealed circuit (freon leak, clogged capillary tube) or the compressor needs to be replaced, special equipment (vacuum pump, pressure gauge station, burner) is indispensable. Attempts to repair “on the knee” in such cases lead to repeated breakdowns.
It is also worth contacting the service if the refrigerator is under warranty. Opening seals on your own or violating the integrity of factory connections automatically voids the manufacturer's warranty obligations. Service center technicians have access to original spare parts and technical bulletins, which ensures quality repairs.
Remember that regular maintenance, cleaning the condenser from dust and checking door seals will extend the life of the equipment and prevent many of the problems described. A timely response to the first signs of unstable operation will save your budget from major expenses.
Is it possible to use a refrigerator if it turns on and off?
It is strictly not recommended. Operation in constant start-stop mode leads to rapid overheating of the motor windings and can cause a fire or complete destruction of the compressor. Products can also deteriorate due to temperature violations.
How much does it cost to replace a starting relay?
The cost of the relay itself usually ranges from 500 to 1500 rubles, depending on the model. The replacement work takes 15-20 minutes and is assessed separately, often during an on-site visit.
Why does the refrigerator hum but does not start after defrosting?
If such a problem appears after defrosting, it is possible that water got into the electrical contacts or into the start relay, causing a short circuit or oxidation. An ice jam could also form in the system, creating excess pressure.
Does the position of the refrigerator affect the start of the compressor?
Yes, if the refrigerator was transported lying down, it needs to stand upright for at least 2-4 hours (preferably a day) before turning it on. The oil must drain into the compressor crankcase, otherwise water hammer and jamming are possible.