The appearance of extraneous sounds in kitchen appliances always causes concern among owners, especially when it comes to cooling systems. Noise in a No Frost refrigerator often becomes a reason for panic, but does not always indicate a critical malfunction. Modern units are complex mechanisms where the movement of refrigerant, the operation of fans and defrost cycles are inevitably accompanied by acoustic effects.
Unlike older models with a drip system, devices with forced air circulation have additional components that create a sound background. Understanding the physics of processes will help you distinguish normal operation from an incipient breakdown. In this article we will analyze in detail the sources of sounds, diagnostic methods and situations when the intervention of a specialist is really necessary.
It is important to notethat the level of perceived noise depends on many factors: the quality of the installation, the material of the kitchen walls and even the filling of the chambers with food. Before sounding the alarm, it is worth conducting an initial analysis of the situation, based on the nature of the sound waves.
The physics of the No Frost system and sound sources
The operating principle of refrigerators with technology No Frost (without frost) is radically different from classic models. Here, moisture does not settle on the evaporator in the form of ice, since dry cold air constantly circulates through the chambers. A powerful fan is responsible for this process, which is the main source of a specific hum. The air is forced through the evaporator located behind the rear wall and distributed through the channels.
The key element that creates background noise is precisely evaporator fan. It can work continuously or turn on cyclically, depending on the management algorithms of a specific brand, for example Liebherr or Bosch. The blades cut through the air, creating aerodynamic noise, which can increase when the blades freeze or foreign objects get into the rotation path.
In addition, there are thermodynamic processes in the system. The refrigerant, passing through the capillary tube and throttle, changes its state of aggregation, which is accompanied by a characteristic gurgling or hissing sound. This is an absolutely normal phenomenon, indicating that Freon circulation is not impaired. Sounds can be especially noticeable immediately after opening the door, when the system tries to quickly restore the temperature.
Normal operating noise: what is considered standard
Many users mistake normal operating sounds for signs of a breakdown. Manufacturers of equipment, such as LG or Samsung, regulate acceptable levels of acoustic pressure, which are usually in the range of 35–45 dB. By comparison, this is the level of quiet conversation or rustling pages. If your unit produces a uniform, monotonous hum, most likely everything is fine with it.
Particular attention should be paid to the sounds that occur when the compressor starts or stops. At this moment, a relay click or a short-term hum may be heard, caused by starting currents and inertia of the motor. It is also considered normal plastic cracking when the temperature inside the chambers changes, since materials expand and contract at different rates.
⚠️ Attention: If you have just installed a new refrigerator, let it sit for several hours before turning it on. Transportation oils must drain into the compressor crankcase, otherwise the noise level at the first start will be significantly higher than normal, and the engine life will be reduced.
The table below shows the main types of sounds that are considered acceptable for working equipment:
| Sound type | Frequency of occurrence | Cause of occurrence | Status |
|---|---|---|---|
| Uniform hum | Continuous or cyclical | Compressor operation | Normal |
| Whistling/Air Noise | When the fan is running | Circulation of air masses | Normal |
| Gurgling/Gurgling | Periodically | Movement of refrigerant in the tubes | Normal |
| Crackling/Clicking | Rarely, when changing mode | Thermal expansion of plastic | Normal |
Mechanical causes of increased noise
If the nature of the sound has changed and began to resemble rattling, clanging or vibration, the reason most likely lies in the mechanics. Often the source of the problem is incorrect installation of the unit. If the refrigerator is not level, vibrations from the running motor are transmitted to the housing and are amplified by resonance. Check the adjustment supports and make sure that the equipment is not touching walls or furniture.
The second common reason is loose fasteners. During long-term use, the screws holding compressorcasings and panels may become loose. All it takes is one loose bolt to turn a quiet operation into a loud noise. It is also worth checking whether the cooling system tubes do not vibrate when touching each other or the walls of the case.
☑️ Diagnosis of mechanical noise
The condition of the fan deserves special attention. If ice is frozen on its blades or a product label gets caught, an imbalance and a characteristic knock will occur. In models Indesit and Ariston a situation often occurs when the bearings of the fan itself are broken, which requires its replacement. Ignoring this problem can lead to a break in the fan wiring or its complete jamming.
Problems with the compressor and electrical system
The most expensive part of the refrigerator is the compressor. If you hear a loud metallic clang, a hum that turns into a howl, or a knock reminiscent of hammer blows, these are alarming signals. Wear of the piston group or the destruction of the motor mount inside the casing leads to the fact that the “heart” of the refrigerator begins to beat against the walls of its body.
Another cause of noise may be problems with the starting relay. If you hear a clicking sound followed by silence when you try to start, or a humming noise that ends abruptly, the relay may not be able to start the engine. In some cases, a “humming without starting” effect is observed when the compressor tries to start, but cannot turn over, creating strong vibration.
What is an inverter compressor?
Inverter motors work differently than conventional ones. They do not turn off completely, but smoothly change power. Therefore, they are quieter, but can produce a high-frequency whistle or hum that changes depending on the load. This is not a breakdown.
⚠️ Attention: Operating a refrigerator with a faulty compressor or relay is unacceptable. The motor can burn out in a matter of minutes, and replacing the compressor is one of the most expensive procedures in repairing household appliances.
If you encounter such symptoms, you must immediately disconnect the appliance from the network. Further operation in this mode will not only not cool the products, but can also lead to a fire in the wiring or complete failure of the unit. Diagnostics of the electrical part requires special instruments, such as a multimeter and a winding tester.
The influence of ice and the defrosting system on acoustics
The system No Frost implies periodic defrosting of the evaporator. The defrost heating element is turned on according to a timer or sensor readings, heating the radiator. At this moment, you may hear the hissing of melted water dripping into the pan, or the crackling of ice breaking off. However, if the defrost system is not working correctly, the noise level may increase.
If the defrost sensor or timer is faulty, excessive noise will build up on the evaporator. The fan, trying to expel the air, begins to touch the ice build-up with its blades. This causes a loud grinding crackling noise that often frightens users. Over time, ice can block the fan completely, and it will burn out along with the motor winding.
It is also worth mentioning the sounds that occur when ice melts in the drainage system. If the drain hole is clogged with debris or grease, water may gurgle without finding a way out or overflow the edge of the pan. Regular cleaning of the drainage helps to avoid these unpleasant acoustic effects and the appearance of puddles under the refrigerator.
When you need to call a technician: critical signs
There are a number of situations when self-repair is not only useless, but also dangerous. If you smell burning wiring, see sparking, or feel electrical current flowing through the refrigerator, stop using the appliance immediately. Also, a reason to call a specialist is the situation when the refrigerator has stopped freezing, but at the same time makes unusually loud sounds.
A specialist is needed if:
- 🔨 The compressor makes the sounds of metal hitting metal.
- 🔥 There is a burning or burning smell rubber.
- 💧 A puddle has formed around the unit, although the drainage is clean.
- 📉 The temperature in the chambers does not fall below +10°C even at the maximum setting.
Professional diagnostics allow you to accurately determine the source of the problem. The technician uses a thermal imager to look for freon leaks, a pressure gauge station to check the pressure in the circuit, and a specialized tool to open the system. Attempts to independently solder the tubes or replace the compressor without evacuation of the system are doomed to failure.
Why does the refrigerator hum louder at night?
At night, the overall noise level in the apartment decreases and the contrast between silence and the operation of technology becomes more noticeable. In addition, at night, the voltage in the electrical network may stabilize or, conversely, jump, which affects the operation of the motor. Also, other devices work during the day, masking the noise of the refrigerator.
Is it possible to lubricate the compressor so that it makes less noise?
No, modern compressors are sealed and do not require lubrication during operation. An attempt to drill a hole for oil will lead to depressurization and instant damage to the unit. If the compressor is noisy due to wear of internal parts, it can only be replaced.
Does the amount of products affect the noise level?
Yes, it does. An empty refrigerator operates with long periods of rest, but when loaded with warm food, the compressor turns on at full power and runs longer. Additionally, full shelves and drawers may resonate or rattle if dishes touch. Make sure that bottles and cans do not touch each other.
What to do if the refrigerator is in a niche?
Installation in a niche requires special attention to ventilation. If the gap between the cabinet walls and the refrigerator is too small, heat will not be dissipated and the compressor will work at its limit, creating more noise. Make sure that the minimum gaps specified in the instructions for your model are observed (usually 5-10 cm).