The situation when the refrigerator clicksbut does not start or makes periodic sounds during operation is familiar to many owners of household appliances. This sound often resembles a metallic impact or dry cracking sound, which can occur at varying intervals. For most users, such noise becomes a source of concern, as it signals possible malfunctions in the operation of the main unit - the compressor.
It is important to understand that not every sound indicates a breakdown. Modern models, especially those with the No Frostsystem, can make characteristic clicks when switching modes or operating the dampers. However, if the sound is accompanied by a lack of cold or the engine hums but does not start, it is necessary to conduct a thorough diagnosis. Ignoring the problem can lead to more serious consequences, including complete failure of an expensive compressor.
In this article we will examine in detail the mechanical and electrical causes of knocking. You will learn how to distinguish normal operation of equipment from a critical malfunction, and what steps you can take on your own, and when it is better to call a specialist. Correct interpretation of sound signals will help save time and budget for repairs.
Normal operation of the compressor and thermostat
The first thing to do when extraneous sounds appear is to determine their nature. If the refrigerator clicks once before the engine starts or after it stops, this is often a sign that the starter mechanism is working properly. When the electric motor is turned on, the contacts close, which is physically accompanied by sound. A similar process, but in reverse order, occurs when the set temperature is reached and the motor is turned off.
Particular attention should be paid to models with electronic control and system No Frost. They have special dampers installed that regulate the flow of cold air. When they move, clicking or cracking noises may also occur. This is absolutely normal and does not require intervention. Thermoregulator is also a source of sound: when the mechanical sensor opens the circuit, it emits a characteristic click, which is sometimes transmitted to the housing.
However, if you notice that the clicks have become too frequent, loud, or are accompanied by attempts to start the engine, which immediately stop, the situation requires checking. A normal work cycle includes long periods of work and occasional breaks. Frequent switching on and off (clocking) harms the equipment.
Faulty compressor start relay
The most common reason that the refrigerator clicks and does not turn on is the failure of the start-protection relay. This small component is responsible for supplying a starting pulse to the motor winding and protecting it from overloads. When the relay wears out or burns out, it tries to start the engine, a click is heard, but the circuit immediately opens due to the lack of proper current or protection.
It is difficult to visually determine the problem without disassembling it, but visually (by ear) it is easy to diagnose. The sound is often described as "knock-knock-knock" at intervals of several seconds or minutes. The engine may hum or twitch slightly, but does not gain momentum. In some cases, the relay may “stick”, causing the compressor to operate continuously, which is also dangerous.
Replacing the relay is one of the few procedures that can be performed independently if you have basic skills and tools. Starting device usually attached to the side of the compressor and removed with a simple movement. The main thing is to purchase exactly the same model, since they differ in the type of compressor and power.
☑️ Diagnostics of the starting relay
Problems with the thermostat and sensors temperature
The thermostat is the “brain” that decides when the refrigerator needs to cool the chamber and when to rest. If this element is faulty, it may give incorrect commands to the compressor. As a result, the refrigerator clicks, trying to turn on, although it is already cold inside, or, conversely, remains silent when the food begins to spoil. Mechanical thermostats have moving contacts that oxidize or burn over time.
In modern models with electronics, temperature sensors (thermistors) perform the role of a thermostat. They don't make sounds themselves, but their incorrect readings cause the control module to randomly turn the relay on and off, causing a series of clicking sounds. If the sensor “lies” about the evaporator temperature, the system may go into an error or an endless restart cycle.NTC-thermistors). They don't make sounds themselves, but their incorrect readings cause the control module to randomly turn the relay on and off, causing a series of clicking sounds. If the sensor "lies" about the evaporator temperature, the system may go into an error or an endless restart cycle.
⚠️ Attention: Before replacing the thermostat, make sure that the capillary tube is not kinked and that the sensing element is tightly adjacent to the evaporator wall. Incorrect installation will lead to incorrect operation of even a new sensor.
To check the mechanical thermostat, you can temporarily close its contacts. If after this procedure the refrigerator starts and freezes normally, then the problem is in the regulator. In electronic systems, you will need a tester to check the resistance of the sensor at different temperatures.
Compressor jamming and oil problems
The most alarming symptom is when the refrigerator clicks, the motor hums for a few seconds, and then there is a loud bang and silence. This often indicates that the compressor is stuck. The piston group inside the sealed unit may have worn out, or the freon system may have become contaminated. In this state, the engine cannot turn over and goes into current protection.
Another reason is thickened oil. If the refrigerator did not work for a long time or was in the cold, the lubricant could lose its properties. When trying to start, the pistons experience enormous resistance, which causes characteristic sounds and the impossibility of starting. Sometimes “boosting” the compressor by applying increased voltage helps, but this is a job for professionals.
Is it possible to revive a jammed compressor?
There is a method of “wedging” by applying voltage to different windings, but its effectiveness is less than 30%. In most cases, a complete replacement of the unit is required, since opening the hermetic unit at home is impossible without losing the seal.
If you hear that the compressor is getting very hot and the relay clicks regularly, it is better not to experiment. Prolonged attempts to start can completely burn out the motor winding, turning the repair from replacing the compressor into buying a new refrigerator.
The influence of voltage in the network and wiring
Unstable voltage in the electrical network is a frequent culprit of problems with household appliances. If the voltage drops below the permissible threshold (usually 190-200 Volts), the compressor cannot start. The relay tries to do this, a click is heard, but the engine only hums. After a few seconds, the protection turns off the power, and the cycle repeats.
It is also worth checking the condition of the socket and plug. Loose connections, oxidation or burning of wires at the connection point can cause sparking and cracking noises, which users mistake for knocking inside the refrigerator. This is especially true for old apartments with aluminum wiring.
To protect expensive equipment, it is recommended to use a voltage stabilizer or surge protector with a surge shutdown function. This will extend the life of not only the compressor, but also the electronic control module.
Comparative table of symptoms and causes
To quickly navigate the problem, use the table below. It will help to compare the observed symptoms with the probable cause of the malfunction.
| Symptom | Probable cause | Difficulty of repair | Need for a technician |
|---|---|---|---|
| One click at on/off | Normal operation of the relay or thermostat | Not required | No |
| Frequent clicks, the motor does not start | Faulty start relay | Low | No (you can do it yourself) |
| Clicks, humming, high compressor heating | Stuck compressor | High | Yes |
| Crackling inside the chamber, no cold | Problem with fan or defrost | Medium | Desirable |
| Chaotic clicks, errors on the display | The control module or sensors are faulty | High | Yes |
Prevention and proper operation
To minimize the risk of problems, it is important to follow the operating rules. It is not recommended to turn the refrigerator off and on. If you did turn it off, restarting is possible no earlier than after 10-15 minutes. This time is necessary to equalize the pressure in the system and cool the compressor.
Regular defrosting (for drip systems) and cleaning the condenser at the back of the refrigerator also prolongs the life of the unit. Dust on the radiator grille causes overheating, which causes the engine to work with overload and wear out faster. Make sure that the refrigerator stands level, without distortions, otherwise vibration may accelerate the destruction of internal components.
⚠️ Attention: Construction details and electrical diagrams may vary depending on the manufacturer and year of manufacture of the model. Before purchasing spare parts, be sure to check the markings on the body of your device with the manufacturer's catalog.
Frequently asked questions (FAQ)
Why does the refrigerator click immediately after defrosting?
After defrosting, condensation could remain in the system, which makes a sound when freezing or contacting hot parts. It is also possible that the thermostat has not yet been adjusted. If the clicking does not stop after an hour of operation, check whether water has entered the electrical contacts.
Is it dangerous if the refrigerator clicks but freezes?
If cooling occurs normally, most likely the thermostat or defrost relay is clicking. It is not dangerous, but requires supervision. If the frequency of clicks increases or a burning smell appears, the equipment needs to be turned off.
Is it possible to replace the start relay yourself?
Yes, if you have basic skills in working with electrical equipment. The main thing is to buy a relay with exactly the same markings. Before replacing, be sure to unplug the refrigerator.
How much does repair cost if the compressor burns out?
Replacing a compressor is an expensive repair, which often amounts to 50-70% of the cost of a new refrigerator. In this case, it is often more advisable to purchase new equipment, especially if the old one is more than 7-10 years old.