The refrigerator turns on and immediately turns off: causes of failure

The situation when the refrigerator turns on and immediately turns offis a classic symptom of a serious malfunction of the compressor or control system. Usually this process is accompanied by a characteristic click, a hum for 2-5 seconds and subsequent silence, after which the cycle is repeated after a certain time interval. In technical language, this phenomenon is often called “cycling” or operation in protection mode.

Ignoring the problem can lead to final failure motor-compressor, the replacement of which costs significant money. The inrush currents that arise at the moment of start strongly heat the windings, and if the engine does not have time to accelerate to operating speed, the thermal protection relay is triggered. Understanding the physics of the process will help you determine whether you can fix the malfunction yourself or whether you need to call a technician.

In this article we will analyze in detail all possible causes: from a simple voltage surge to a complex interturn short circuit. We will look at the design of the starting relay, the operation of the thermostat and the effect of the refrigerant on the operating cycle of the unit. Diagnostics requires care and compliance with electrical safety rules when working with conductive elements.

Problems with the starting relay and compressor

The most likely reason the refrigerator clicks and does not startlies in the start relay. This small unit is responsible for supplying voltage to the starting winding of the engine at the moment of start. As soon as the rotor picks up speed, the relay should turn off the starting circuit. If the mechanism is stuck or the contacts are burnt, the engine does not receive the required impulse and stalls, and the protection opens the circuit.

The second option is a malfunction of itself. motor-compressor. Over time, the winding insulation can become damaged, resulting in an inter-turn short circuit. In this case, the current in the winding increases sharply, the thermal relay heats up and opens the contacts to prevent a fire. You can determine the short circuit using a multimeter by measuring the resistance between the contacts and the housing.

⚠️ Attention: If you hear a hum that lasts less than 5-10 seconds, followed by a shutdown click, this is the operation of the thermal release. Do not try to artificially close the relay contacts to test the compressor, this may lead to a fire.

The third factor is the mechanical wedge of the compressor. The piston group may get stuck due to exhaustion or lack of lubrication. The engine tries to turn the shaft, hums, but physically cannot budge, after which the protection is triggered. In such cases, only replacing the unit often helps.

Malfunctions of the thermostat and sensors

The thermostat (thermostat) is a device that gives the command to turn on the compressor when the temperature in the chamber rises. If the contacts inside the thermostat are burnt or oxidized, the circuit may open immediately after closing. As a result the refrigerator blinks: the indicator lights up, a click is heard, but a full start does not occur.

In modern models with a system No Frost and electronic control, temperature sensors (thermistors) are used instead of a mechanical thermostat. If the sensor transmits incorrect data to the control module (for example, it shows that the temperature has already been reached, although the chamber is warm), the controller may briefly try to start the compressor and immediately stop it due to desynchronization of the readings.

It is also worth checking the capillary tube of the thermostat. If it has moved away from the evaporator or has lost its seal, the sensing element will not respond correctly to temperature changes. Mechanical thermostats often have an adjusting screw, but if the problem is inside the sealed bellows tube, only replacing the assembly will help.

Failures in the electronic control module

In new generation refrigerators, all processes are controlled electronically control module. The board analyzes the signals from all sensors and makes a decision to start the compressor. If the elements of the power part on the board are burnt out (for example, a triac or switching relay), it can send an impulse to start, but not hold the voltage, or it can immediately record an error and go into protection.

A frequent cause of failures is oxidation of contacts on the connectors or moisture ingress. Condensation can flow down the wires into the module housing, causing a short circuit in the tracks. A visual inspection of the board often reveals blackened areas, swollen capacitors or traces of burning, which indicates the need to replace the module or resolder it.

Sometimes the problem lies in a software failure of the “brains” of the refrigerator. In this case, a complete reset can help, if such a function is provided by the manufacturer technicians. However, if the hardware is damaged, software methods will be useless.

Problems with the refrigerant and circulation system

Freon leakage is one of the hidden reasons for unstable operation. When the amount of refrigerant in the system is critically reduced, the compressor runs “idle”. The suction pressure drops, the motor overheats, as the returning gas cools the windings, and the thermal relay turns it off. After cooling, the cycle is repeated.

The other extreme is a clogged capillary tube or filter-drier. A “plug” forms in the system, the discharge pressure rises sharply, and the compressor cannot push the refrigerant. This creates a colossal load on the engine, which immediately goes into protection. A characteristic sign of a blockage is a hot condenser grille only at the beginning and cold at the end, as well as the absence of the characteristic noise of gas flow.

⚠️ Attention: Work with refrigerant requires a license and special equipment. An independent attempt to refuel or replace the filter without evacuation of the system will lead to rapid failure of the compressor.

It is important to note that if freon leaks The refrigerator stops freezing it is effective even if the compressor is running. If you notice that the back wall is not cooling, and the compressor constantly turns on and off, the probability of a leak or blockage is more than 80%.

External factors and electrical network

Unstable voltage in household network is a frequent culprit of problems. If the voltage drops below 190-200 Volts, the starting torque may not be enough to turn the compressor rotor. The engine hums, the current increases, and the protection turns off the unit. A similar situation occurs during sudden power surges.

A faulty outlet or extension cord can also create additional resistance. Poor contact at the plug connection point causes heating and voltage drop, which is perceived by equipment as an emergency situation. Always check that the plug fits tightly in the socket and that the socket body has not melted.

To protect expensive equipment, it is recommended to use a voltage stabilizer or at least a voltage control relay. This device will turn off the power if the network parameters go beyond acceptable limits, preserving electronics and motor the refrigerator.

Diagnostics and fault table

To accurately determine the cause, it is necessary to carry out sequential diagnostics. Start by visually inspecting and listening to the sounds the unit makes. Then, if you have the skills, you can ring the electrical circuits. Below is a summary table that helps classify the symptoms.

To carry out diagnostics, you may need a multimeter. With its help, the integrity of the compressor windings is checked (the resistance between the starting and operating windings and the housing must be certain, but not zero or infinite). The continuity of the circuit through the thermostat and the start relay is also checked.

When you need to call a technician

If you have identified that the problem lies in a freon leak, a clogged system or mechanical damage to the compressor, independent repair is impossible without special tools. Requires a vacuum pump, a pressure gauge station and a supply of refrigerant. Attempts to “treat” the system with sealants often lead to complete failure of the refrigerator.

A ​​technician is also needed if the electronic control module has burned out and cannot be restored by resoldering individual elements. In modern models Samsung, LG, Bosch boards can cost up to 50% of the price of a new refrigerator, so it is important to get an accurate estimate of the cost of repairs.

⚠️ Attention: By opening the sealed circuit of a refrigerator without a license, you are violating environmental regulations and risk injury from high pressure or refrigerant. It is better not to touch the sealed circuit yourself.

If after replacing the start relay and checking the thermostat the situation has not changed, most likely the problem is deeper. Do not delay contacting service, as the compressor operating in constant start-stop mode will quickly burn out completely.