The situation when the refrigerator starts to hum and then suddenly stops after a few seconds is a classic symptom of a serious breakdown or protective reaction of the system. Owners of household appliances often face panic when compressor it makes a loud click, but does not start. This is not just a temporary failure, but a signal that the electrical circuit is forcibly broken in order to prevent failure of the expensive motor.
The reasons for this behavior can be hidden either in a banal voltage surge or in a deep mechanical or electrical malfunction. unit. If you ignore these symptoms and continue to try to turn it on, you can lead to the need for a complete replacement of the compressor. Therefore, it is important to immediately carry out initial diagnostics to understand whether the problem can be fixed on your own or whether you need to call a technician.
In this article we will consider in detail all possible scenarios, from a burnt-out starting relay to an interturn short circuit of the windings. Understanding the physics of the process will help you save time and money by avoiding unnecessary expenses on the services of service centers in cases where the repair is simple. It is critically important at the first sign of the refrigerator “blinking” to turn off the power to the device and not turn it on again until the cause is determined.
The principle of operation of the starting system and protective mechanisms
To understand, why an emergency shutdown occurs, you need to briefly disassemble the device start relay. This small element is responsible for supplying voltage to the starting winding of the engine at the moment of start. As soon as the compressor rotor reaches the required speed, the relay should turn off the starting circuit. If this does not happen or the current in the circuit exceeds the norm, the starting relay comes into play thermal relay.
Thermal protection is a bimetallic plate that bends under the influence of heat. When there is a sharp jump in current, characteristic of a jammed rotor or a short circuit, the plate instantly opens the contacts. It is this click that you hear before the refrigerator goes silent. Cyclic switching on occurs because after cooling the plate returns to its original position and the cycle repeats.
The frequency of such startup attempts depends on the cooling time of the protective element. Typically the interval is from 2 to 15 minutes. If you observe that the refrigerator is trying to turn on every 30 seconds, this indicates a critical malfunction in the electrical part or mechanical jamming.
- 🔌 The starting relay sends an impulse to the starting winding to create torque.
- 🛡️ The thermal relay breaks the circuit when the permissible current is exceeded or temperature.
- ⚙️ The compressor is a sealed motor that does not require lubrication during operation.
Why does the protection not work instantly?
The bimetallic plate takes a split second to heat up and bend. This time is necessary to survive short-term power surges during normal starting, which do not pose a danger.
Faults in the starting and thermal relays
The most common reason why the refrigerator clicks and turns off is the failure of the starting relay. Inside this device there is a coil or a posistor (in modern models) that controls the contacts. Over time, the contacts can burn and the plastic case melts, which leads to sticking or, conversely, the inability to close the circuit.
If the relay is faulty, it can supply voltage to the starting winding constantly, causing an overload, or not supply it at all, which is why the engine cannot move. In both cases, the current in the working winding increases, and thermal protection emergency cuts off the power. Visually, traces of burning or melting are often visible on the relay.
⚠️ Attention: When replacing the relay, strictly monitor the orientation of the device. Some relay models only work in a certain position (up arrow), others are universal. Incorrect installation will lead to instant combustion of the new element.
Diagnostics can be carried out by testing the contacts with a multimeter. However, given the low cost of the spare part, it is often easier to replace the element with a new one that matches the markings. Please note that relays for different brands, such as Indesit, Atlant or LGmay have different designs and are not interchangeable.
☑️ Start relay diagnostics
Problems with the compressor: interturn short circuit and wedge
If replacing the relay did not help, the situation becomes more serious. The second most likely reason is interturn short circuit in the compressor motor windings. If the insulation of the wires inside the motor is damaged, the winding resistance drops, which causes a sharp increase in current consumption. The thermal relay detects this excess and breaks the circuit.
Another option is a mechanical compressor wedge. This happens when the rubbing parts inside the hermetic unit jam due to exhaustion, lack of oil or metal shavings. The motor tries to turn the shaft, but physically cannot budge, which is also perceived by the protection as an emergency.
A short circuit can be diagnosed by measuring the resistance of the windings. It must be within certain limits (usually 10-30 Ohms for working and 20-50 Ohms for starting, depending on the model). If the resistance approaches zero or infinity, the compressor is faulty. Also, a sign of a wedge may be a dull hum when trying to start.
If the diagnosis of “burnt compressor” or “wedge” is confirmed, the repair requires replacing the unit. This is a labor-intensive process, including opening the system, soldering, vacuuming and filling freonwhich only a qualified technician with equipment can do.
The influence of wiring and starting currents
Often the problem lies not in the refrigerator, but in the state of electrical wiring in an apartment or house. Old wiring with aluminum wires, oxidized contacts in the socket, or the use of extension cords with insufficient cable cross-section create high resistance. This leads to a voltage drop at the moment starting current, which is 5-7 times higher than the rated one.
At low voltage, the engine cannot develop the necessary power to start, the current remains high, and thermal protection turns off the device. It is also worth checking the socket: if it is loose or the contacts inside it are burnt, this causes sparking and unstable power.
Try to plug the refrigerator into another outlet, preferably in another room, using a high-quality surge protector or directly. If the problem disappears, then the problem was with the connection point. Do not ignore this fact, as poor contact can lead to a fire.
- 🏠 Old wiring cannot withstand peak loads when the motor starts.
- 🔌 The use of extension cords is often the hidden cause of unstable operation.
- 📉 A voltage drop in the network below 190V also interferes with normal launch.
Comparative table of symptoms and causes
To simplify diagnosis, we suggest referring to the summary table. It will help you compare the symptoms you observe with the most likely malfunction. Remember that an accurate diagnosis can only be made by a specialist after instrumental measurement of parameters.
| Symptom | Probable cause | Difficulty of repair | Necessary actions |
|---|---|---|---|
| Click through 3-5 seconds, silence | Malfunction of the starting relay | Low | Replacement of the relay |
| Humming and sharp clicking | Compressor wedge | High | Replacing the compressor |
| Burning smell, black residue | Short circuit in wiring or relay | Medium | Electrical inspection |
| Works only with a push | Winding wear or mechanical wear | High | Unit replacement |
| Switches off in different sockets | Problem inside the refrigerator | Depends on the node | Diagnostics of nodes |
The role of the thermostat and the electronic module
Although less often, the cause of cyclic switching can be a faulty thermostat (thermostat). If its contacts are stuck in the “on” position, the compressor will run without stopping until the thermal overheat protection is triggered. However, in this case, the cycles will be longer (minutes of work, seconds of rest).
In modern models with a system No Frost and electronic control, the main control module is responsible for starting the engine. If triacs or other elements of the compressor circuit are burned out on the board, the module may send incorrect signals, causing chaotic switching on and off.
Electronics diagnostics require special knowledge and circuits. If you find that the relay and compressor are working properly, and the mains voltage is stable, most likely the problem lies in the “brains” of the refrigerator. In such cases, flashing or replacing the module is often required.
⚠️ Attention: Electronic modules are sensitive to voltage surges. If lights flicker frequently in your area, it is recommended to install a voltage stabilizer to protect all household appliances.
What to do: step-by-step algorithm of actions
If you are faced with the problem described, do not panic. Act consistently so as not to worsen the situation. First of all, unplug the refrigerator and let it stand for at least 20-30 minutes. This is necessary for the thermal relay to completely cool down and defrost ice in the system, if it may have formed.
After a pause, plug the device into another, known-to-work outlet without using extension cords. Listen to the sounds: if after 10-15 seconds there is a click and the refrigerator is silent, the problem is inside. If the hum continues for a long time and stops abruptly, the compressor may be jamming.
For those who have skills in working with electrical equipment, the next step is a visual inspection of the start relay. Remove the plastic casing from the compressor, disconnect the relay and shake it. If something rattles inside like a rattle, the part definitely needs to be replaced. Otherwise, it’s better not to risk it and contact the service center.
Frequently asked questions (FAQ)
Is it possible to temporarily use a refrigerator with a faulty relay?
It is strictly not recommended. Constant attempts to start with a faulty relay create a colossal load on the compressor windings. This can quickly lead to an interturn short circuit and complete failure of the motor, the repair of which will cost several times more than replacing the relay.
Why does the refrigerator hum for 5 seconds and turn off after defrosting?
If the problem appeared immediately after defrosting, moisture may have entered the system and frozen in the capillary tube (ice jam), creating excess pressure. The contact in the relay connector could also have oxidized due to humidity. Let the device dry for a day.
How much does it cost to replace the start relay?
The cost of the relay itself usually varies from 500 to 1500 rubles, depending on the model of the refrigerator. The replacement work takes 15-20 minutes and is assessed separately. This is one of the cheapest types of repairs.
Does low voltage in the network affect frequent switching on?
Yes, at a voltage below 190-200 Volts, the compressor cannot develop the required power to start. The current remains high, the thermal relay heats up and turns off the motor. The solution is to install a voltage stabilizer.