The constant hum coming from the kitchen can unsettle even the calmest person. When the refrigerator is humming without a break, this is not just background noise, but a signal that the system is operating in an emergency or incorrect mode. Unlike the usual rhythmic switching on and off, a continuous hum often indicates an overload of the equipment or a violation of heat exchange, which can ultimately lead to the failure of expensive components.
Many owners of household appliances ignore changing the sound profile of the device until the food stops freezing. However, if compressor works for wear, it consumes significantly more electricity, and its resource is reduced significantly. It is important to understand that modern models, such as LG or Bosch, are equipped with self-diagnosis systems that can block startup in case of critical errors, but old or simple units will work until the last.
In this article we will analyze in detail the mechanical and electrical causes of the malfunction, as well as methods for eliminating them. You will learn to distinguish normal operating noise from a pathological hum that requires the intervention of a specialist. If you hear clicks or knocking along with the hum, and the products begin to deteriorate, immediately disconnect the device from the network.
⚠️ Attention: Long-term operation of the compressor without stop cycles leads to overheating of the windings and melting of the insulation, which creates a risk of short circuit.
Violation of installation rules and thermal conditions
The most commonplace, but common reason why the refrigerator is humming continuously is the incorrect location of the unit in space. If the device is installed too close to the wall, the radiator grille on the rear panel cannot effectively release heat to the environment. As a result, the refrigerant does not have time to cool and condense, temperature sensors detect insufficient cooling of the chambers and do not give a command to turn off the motor.
In addition, the source of the hum can be vibration transmitted to interior items. If the body of the device touches a kitchen unit, stove or other equipment, a resonance occurs, increasing the sound of the engine. It is also worth checking whether the unit is level: misalignment can cause displacement of the internal tubes and a change in the nature of the noise.
For normal air circulation, it is necessary to leave gaps between the housing and the walls. Usually it is 5-10 centimeters on the sides and back. If the kitchen is designed so that the refrigerator is built into a niche, make sure that there are ventilation holes there.
Problems with the No Frost system and the fan
In models with the system No Frost a special fan located in the freezer is responsible for the circulation of cold air. If the refrigerator is humming, and the sound is more like a crackling or howling, the problem may lie in this particular node. Over time, the fan bearings wear out, or ice builds up on the blades, causing imbalance and increased noise during rotation.
Another reason for constant operation in such models is freezing of the evaporator. If the automatic defrosting system fails, the ice coat blocks the airflow. The temperature sensor in the main chamber does not receive cold, so the compressor continues to work without stopping, trying to achieve the set parameters.
Diagnostics of the fan requires partial disassembly of the freezer. It is necessary to remove the back panel and check the free movement of the impeller. If it turns with difficulty or makes a grinding noise, the part requires replacement.
How to check the fan without disassembling?
Listen to the sound: if the hum intensifies when you open the freezer door (in some models the fan stops when opened), then the problem is most likely not in it. If the sound changes or disappears, check the bearings.
Malfunctions of the thermostat and sensors
Control electronics are the “brains” of the refrigerator. If thermostat (the thermostat) is faulty, it may send false signals that the chamber is too warm. In this case, the compressor is commanded to run continuously, ignoring the actual temperature inside. In mechanical models, this is often solved by replacing the capillary tube of the thermostat.
In modern electronically controlled devices, the temperature is controlled sensors (thermistors). If one of them is "lying" or has poor contact in the circuit, the control module will not start the shutdown cycle. Sometimes the problem lies not in the sensor itself, but in oxidation of the contacts or a break in the wiring going to it.
Checking the thermostat at home is possible with a multimeter in dial mode. When the temperature of the sensing element changes, the circuit should open and close. If there is no contact or it is constantly there, the part is faulty.
| Symptom | Possible cause | Sound character |
|---|---|---|
| Buzzing, does not turn off | Thermostat is faulty | Uniform hum of the motor |
| Humming and clicking | Start relay | The hum is interrupted by clicks |
| Strong hum + vibration | Compressor shock absorbers | Low-frequency hum, rattling |
| Humming, but not cooling | Freon leakage | The motor is idling |
Wear of the compressor and start relay
The heart of the refrigerator is compressor. If it starts buzzing louder than usual and does not stop, this may indicate that its resource is exhausted. The piston group wears out, the valves lose their tightness, and the engine is forced to work longer to gain the required pressure in the system. In such cases, overheating of the motor housing is often observed.
The starting relay deserves special attention. This small element is responsible for starting the engine. If the relay contacts are burnt or the mechanism is stuck, the compressor may hum but not start, or may run continuously. Replacing a relay is one of the simplest and cheapest repair procedures, which you can do yourself if you have basic skills.
It is worth noting that inverter compressors installed in models Samsung and LGoperate differently. They do not turn off completely, but only reduce the speed. Therefore, a quiet but constant hum may be normal for them if the temperature in the chambers is stable.
☑️ Compressor diagnostics
Refrigerant leak and capillary blockage
If the refrigerator is humming without stopping, but the chambers are warm, high possibility of freon leakage or capillary tube blockage. The pressure in the system drops, and the compressor tries to compensate by operating at maximum load. This is the most dangerous mode for the engine, since the cooling of the windings in such models is often tied to the circulation of the refrigerant.
If there is a freon leak, the motor can run for days, but the cold is not produced in the required volume. Visually, this can be noticed by the swelling of the side walls (in some models) or the lack of heating of the condenser at the back. The blockage is often accompanied by a characteristic gurgling sound or a complete absence of sound of gas movement, despite the operation of the motor.
Elimination of these problems requires specialized equipment: a vacuum pump, a pressure gauge station and a supply of refrigerant. It is almost impossible to refill the system on your own with high quality.
⚠️ Attention: An attempt to independently solder tubes or replace the filter-drier without evacuation of the system will lead to rapid failure of the compressor due to moisture and air.
Vibration and resonance of the housing
Sometimes the cause of noise lies not in the internal components, but in the way the case interacts with the floor surface. If the legs of the refrigerator are not adjusted to the level, a misalignment occurs, which is transmitted to the compressor frame. This causes increased vibration, which transforms into a low-frequency hum.
It is also worth checking the compressor mounting bolts. Over time, they may weaken and the rubber shock absorbers will no longer effectively dampen vibration. In this case, the metal begins to vibrate, creating an unpleasant acoustic background. Tightening the bolts often solves the problem without replacing parts.
Do not forget about external factors: a microwave standing nearby, a pan filled with water on a shelf, or loose bottles in the door can resonate with the frequency of the engine, creating the illusion of a breakdown of the refrigerator itself.
Frequently asked questions (FAQ)
Is it normal for a new refrigerator to hum in the first days of operation?
Yes, this is normal. After transportation, the oil in the compressor needs time to be evenly distributed throughout the system. Also in new models there is a process of grinding in parts. If after 2-3 days the hum does not subside and the temperature does not drop, you should contact the service.
Can a refrigerator hum due to a large amount of food?
Yes, if you have loaded a lot of warm products into the chamber at once, the compressor will work without stopping until it cools the entire volume. Try not to load the refrigerator by more than 30% of its nominal value at a time and let the products cool to room temperature before storing.
Why does the refrigerator hum only at night?
At night, the overall noise level in the apartment drops, and operating equipment becomes more noticeable. However, if the hum intensifies at night, this may be due to a drop in voltage in the electrical network during the hours of minimum consumption, which makes the motor work harder.
How long can a refrigerator operate without stopping?
In normal mode, the operating cycle is 15-40 minutes, followed by a pause. In the “Super Freeze” mode or in extreme heat, the device can operate for several hours. Continuous operation for more than 12-20 hours is considered an emergency.
Is hum dangerous for neighbors?
A constant low-frequency hum can be transmitted through building structures and disturb neighbors. If the problem is vibration, installing the unit away from load-bearing walls and using anti-vibration substrates will help solve the social aspect of the problem.