A situation when a household appliance makes a loud hum and then suddenly goes silent can cause panic in any owner. Cyclic operation technicians often indicate that the system protection is triggered due to overload or component failure. Unlike a steady, quiet hum, an intermittent noise requires immediate attention as it can lead to food spoilage and costly repairs.
Most often, the problem lies in an attempt compressor to start, which ends in failure due to a blocked rotor or electrical failure. It is important to understand that the sound of the engine itself is normal, but its abrupt cessation along with the absence of cold is an alarming symptom. Next, we will analyze in detail the mechanical and electrical reasons for this behavior of the unit.
You should not ignore the first signs of instability, even if the refrigerator is still freezing. Constant attempts to start without entering operating mode can damage the motor windings in a matter of hours. In some cases, a simple rearrangement is enough to eliminate the noise, but often a technician’s intervention is required.
Mechanical causes of vibration and sudden attenuation
The first thing that needs to be excluded is physical factors not related to the breakdown of internal components. If the refrigerator hums and then suddenly stops, it may simply vibrate against the floor or cabinet wall. Cabinet resonance increases the sound of the motor, creating the illusion of a malfunction. Check whether the equipment is level using a building level.
Often the cause of noise is improper installation. If the feet are not adjusted, the compressor will cause the entire housing to vibrate during operation, which may block the normal movement of the pistons or trigger the vibration sensors (if equipped). It is also worth checking the distance to the walls: a too tight fit can transmit vibration to the furniture, increasing the hum.
There may also be objects inside the chamber that cause noise. Glass shelves or dishes that come into contact with the walls during vibration produce a rattling noise that the user may perceive as the hum of a motor. Make sure that the food does not touch the back wall where the evaporator is located evaporator.
If you notice that the noise occurs only when opening the door or loading food, the problem is almost certainly a mechanical contact. In this case, it is enough to simply rearrange the jars or straighten the shelf. However, if the hum comes specifically from the motor-compressor and is accompanied by its stopping, the matter is more serious.
⚠️ Attention: If the refrigerator makes a loud metallic clang before stopping, immediately unplug it. This may indicate destruction of the compressor suspension or solid particles entering the cylinder.
Problems with the starting relay and electrical system
One of the most common reasons why the refrigerator hums for 5-10 seconds and turns off is a malfunction starting relay. This small element is responsible for supplying voltage to the motor windings at the moment of start. If the relay is “stuck” or burned out, the motor hums, trying to move the rotor, but the protection current opens the circuit.
It is difficult to visually determine if the relay is broken without disassembling it, but an indirect sign is a characteristic click before starting and silence after it. Inside the relay there is a coil and contacts that oxidize or burn over time. Modern models use positor relays, which fail less frequently, but also require checking.
In addition to the relay, the problem may lie in the wiring or contacts. Oxidation of the terminals leads to a voltage drop, due to which the compressor cannot develop the required power to start. As a result, a strained hum is heard, and then the thermal protection relay is activated, opening the circuit until it cools down.
How to check the relay yourself?
To check, you can gently shake the removed relay near your ear. If you hear the sound of broken glass or ceramics inside, the part is definitely faulty and needs to be replaced. However, only a technician with a tester can make an accurate diagnosis.
Replacing the start relay is not the most difficult procedure, but it requires compliance with safety precautions. Before any electrical manipulations, be sure to unplug the device from the outlet. An incorrectly selected relay can lead to combustion of the compressor itself, which is much more expensive.
Compressor malfunctions: jamming and wear
The most serious diagnosis is compressor jamming. The mechanical part of the motor consists of a piston group that compresses the refrigerant. If parts wear out, moisture enters the system, or oil is lost, the pistons can seize. At this moment, the motor hums, the rotor cannot turn, and the protection is triggered.
Sometimes the compressor can be “seized” by applying increased voltage, but this is a temporary measure. If the refrigerator starts to hum and switches off, the resource of the unit is most likely already exhausted. Attempts to revive an old motor often lead to its complete failure after a short time.
Another reason is an interturn short circuit in the motor windings. In this case, the motor may hum more than usual, become very hot and quickly turn off due to the thermal switch. The smell of burning or scorched insulation is a sure sign of an electrical fault in the windings.
Diagnostics of a compressor requires special tools, such as pressure gauges and resistance testers. You can independently only ring the windings for breaks or short circuits, but it is impossible to evaluate the mechanical part without opening the casing.
☑️ Compressor diagnostics
The influence of the refrigerant and the circulation system
Impaired circulation freon can also cause strange sounds and stops. If there is an ice or debris blockage in the system (often in the capillary tube), the compressor tries to push gas, the pressure rises, and the motor stalls. After cooling, the ice melts, the pressure equalizes, and the cycle repeats.
Refrigerant leakage causes the compressor to run “idle”. Although most often this causes continuous operation without stopping, in some configurations the sensors can initiate on-off cycles, accompanied by a change in the operating sound.
It is important to note that the system is sealed and you cannot add freon or clean the capillary yourself. Requires evacuation of the system and filling by weight. Unprofessional intervention will lead to moisture and acid entering, which will kill the compressor.
| Symptom | Probable cause | Necessary actions |
|---|---|---|
| Buzzing for 3-5 seconds, clicking, silence | Faulty start relay | Replacement of relay |
| Strong hum, heating of the case, shutdown | Stuck compressor | Replacement compressor |
| Gurgling, then silence | Normal operation or clogged | Observation or cleaning the system |
| Vibration, rattling | Incorrect installation | Legs alignment |
No Frost system and fan
In refrigerators with a system No Frost the fan is responsible for air circulation. If its blades are frozen to ice or debris is wrapped around them, the fan motor may hum and stop. This is often perceived as a problem with the main compressor.
Ice blockage in the evaporator passage can also create airflow resistance. The fan tries to spin, makes noise, but cannot turn. After defrosting (turning off for 10-12 hours), the problem may temporarily disappear, but if defrost heating element or the sensor is faulty, the ice will grow again.
Checking the fan requires removing the back panel in the freezer. If the blades are difficult to spin by hand or the bearing is heard crunching, the assembly must be replaced. Ignoring this problem will lead to overheating of the fan motor and its combustion.
⚠️ Attention: Do not try to defrost the refrigerator with a knife or sharp objects. Damage to the evaporator tubes will lead to an immediate release of freon and expensive repairs.
Algorithm of actions when a problem is detected
If you encounter the symptoms described, act consistently. First, rule out external factors: check the outlet, the voltage, the position of the refrigerator. Then listen: where exactly the sound originates - from below (compressor) or inside the chamber (fan).
Try to completely defrost the refrigerator within 24 hours. This will help eliminate ice jams and check whether the behavior of the equipment is related to freezing. If after turning on the problem repeats after a few hours, the problem is in the hardware.
Independent repair of the electrical part is possible only if you have the skills and tools. If you don't know how to use a multimeter or don't know where the start relay is, it's better not to take risks. A mistake can cost you a new compressor.
When you need to call a technician
Calling a specialist is required if you need to open the refrigeration circuit (filling with freon, replacing the compressor, cleaning the capillary). These works require a license and special equipment. A technician is also needed for accurate diagnosis of electronics, if the model is equipped with a complex inverter inverter control
Do not delay repairs if the refrigerator has stopped freezing. Products may deteriorate, and further operation of a faulty compressor "to wear and tear" will make repairs economically impractical. It is better to replace the part at the first sign of instability.
Professional diagnostics often include checking the current consumption and pressure in the system. Only an integrated approach allows you to say exactly why the refrigerator hums and stops in your particular case. Saving on diagnostics can lead to the purchase of unnecessary spare parts.
Frequently asked questions (FAQ)
Can a refrigerator hum? and turn off due to power surges?
Yes, if your network has unstable voltage, the compressor may not start or may be overloaded. In such cases, it is recommended to install a voltage stabilizer or voltage control relay to protect the equipment.
Is it normal for the refrigerator to make sounds when defrosting?
Yes, in No Frost systems, during defrosting, ice melts and drips onto the heating element, which can cause hissing or crackling. The sound of ice breaking is also possible. This is normal if it is not accompanied by the engine stopping.
How long should the compressor work normally?
In normal mode, the compressor operates cyclically: it works for about 10-20 minutes and rests for 20-40 minutes. If it turns on for 10 seconds and turns off, this is an emergency mode.
Why does a new refrigerator hum loudly?
New models may hum louder due to more powerful compressors or installation features. Give him 2-3 days to work idle. If the noise does not subside and is accompanied by vibration, check the shipping bolts (if any) and the adjustment of the legs.