Modern units with the system No Frost are designed to relieve the owner from the need for manual defrosting, ensuring uniform distribution of cold. However, this comfort comes at a price: technically complex components often become a source of extraneous sounds that were not present in older models with a drip system. If your refrigerator begins to hum, crackle or whistle, you cannot ignore this, since extraneous noise can signal a serious breakdown.
Unlike classic models, where the only source of sound was the compressor, additional mechanisms work in systems with forced air circulation. Fans, defrost heating elements and sensors create a complex acoustic background, which normally should be barely noticeable. Understanding the physics of the processes inside the chamber will help you distinguish the normal operation of the equipment from the harbinger of an expensive repair.
In this article we will analyze in detail all the possible causes of noise, from a banal distortion of the case to failure compressor. You will learn how to carry out initial diagnostics on your own and understand in which cases calling a specialist is inevitable. A competent assessment of the nature of the sound is the first step to saving the family budget.
Design features of the No Frost system
To understand the source of noise, it is necessary to imagine the internal structure of the unit. In refrigerators No Frost the evaporator is hidden behind the back wall of the chamber, and cooling occurs due to constant air circulation. A special one is responsible for this process, which pumps cold masses into the chamber and returns them back to the evaporator. fan, which pumps cold masses into the chamber and returns them back to the evaporator.
It is the presence of moving mechanical parts that distinguishes these models from quieter analogues. Cyclic operation defrost systems also makes its own adjustments: periodic switching on of heating elements and changes in temperature conditions cause thermal expansion of plastic and metal, which is often heard as crackling or clicking.
⚠️ Attention: The design of the evaporation unit may differ from one manufacturer to another. For some models LG or Samsung the fan is located in the freezer, while for others it is in the technical compartment. The exact location of the components is always indicated in the technical documentation.
It is important to consider that the intensity of the fan is controlled electronically depending on the set temperature and the frequency of door openings. With a sharp increase in load, engine speed may increase, which is subjectively perceived as an increase in hum. This is a normal situation that does not require intervention.
Natural sounds of the refrigerator
Not every sound is a sign of a malfunction. Many owners panic when they first hear a characteristic gurgling or hissing sound, although these sounds indicate normal circulation refrigerant through the pipes of the system. The refrigerant changes from a liquid to a gaseous state, and this physical process is inevitably accompanied by acoustic effects.
It is also worth mentioning thermal expansion. The plastic of the inner housing and metal elements may make a clicking noise when there is a sudden change in temperature (for example, after a defrost cycle). If these sounds occur periodically and are not accompanied by other symptoms, there is nothing to worry about.
- 🔊 Uniform low-frequency hum of a running motor-compressor.
- 💧 Quiet gurgling or gurgling in the refrigeration circuit tubes.
- 🔥 Periodic cracking of plastic when the temperature inside the chambers changes.
- 💨 A slight whistle of air passing through the air ducts of the system No Frost.
However, if the nature of the sounds changes, vibration or metallic clanging appears, this is a reason to conduct a more in-depth diagnosis. Users often confuse normal operating noise with an emerging problem, so it is important to listen to the nuances of the sound.
Problems with the fan: the main cause of noise
The most common cause of a loud hum or howling in refrigerators No Frost is a malfunction of the fan. This unit ensures air circulation, and if it fails, the cooling efficiency drops and the noise level increases. Often the problem lies in the bearings or bushing of the fan motor, which wear out over time.
Another common situation is ice freezing on the blades or in their rotation zone. If the defrost system is not working properly or the drain hole is clogged, moisture can freeze right in the path of the blades. In this case, you will hear a characteristic cracking or knocking sound when the blades begin to touch the ice.
For diagnostics, you must carefully remove the back panel in the freezer (after defrosting the unit for at least 12 hours). A visual inspection will indicate the presence of ice or play in the fan shaft. If the shaft wobbles or rotates with force, the unit will need to be replaced.
☑️ Fan diagnostics
In some models, for example, brand Indesit or Ariston, the fan may make noise due to dried grease in the bearing. Theoretically, it can be lubricated, but practice shows that replacing it with a new original unit gives a more durable result and guarantees silence.
Faults of the compressor and start relay
The compressor is the “heart” of the refrigerator, and its malfunctions are often accompanied by a change in the sound profile. If the unit begins to hum significantly louder than usual, and the sound becomes metallic or clanging, this may indicate wear on the internal mechanical parts of the motor or problems with the fastening.
Particular attention should be paid to the starting relay. If this element fails, the compressor may attempt to start, make a loud clicking and humming noise, but then stall. Such cycles may repeat every few minutes. This is a dangerous operating mode that can lead to burning of the motor windings.
| Sound type | Probable cause | Required actions |
|---|---|---|
| Loud metallic clanging | Destruction compressor suspension | Replacing shock absorbers or compressor |
| Intermittent hum and clicks | Faulty start relay | Replacing the start relay |
| Constant strong hum | Wear of the motor-compressor | Pressure diagnostics, replacement possible |
| Vibration of the housing | Incorrect installation or touching of the tubes | Adjusting the legs, bending the tubes |
Repairing the compressor at home is impossible and not economically feasible. If the diagnosis of “death of the compressor” is confirmed, a call to a qualified technician with equipment for filling freon and vacuuming the system is required.
Is it possible to replace the compressor yourself?
Theoretically, yes, if you have soldering skills and a vacuumizer. However, without a license to work with freons and special tools, it is extremely difficult to properly seal the circuit and charge it with refrigerant. An error will lead to rapid breakdown of the new compressor.
The effect of incorrect installation on the noise level
Often the reason for loud operation lies not in the internal components, but in incorrect installation. The refrigerator No Frost requires a perfectly flat surface. If the unit is skewed, vibration from the running motor is transmitted to the body and amplified by resonance, creating an obsessive hum.
It is also important to maintain the gaps between the back wall of the refrigerator and the wall of the room. Placing it too close disrupts the heat transfer of the condenser (the black grille at the back), which causes the compressor to work longer and harder, and therefore produce more noise.
Check whether the refrigeration pipes are touching each other or the cabinet walls. When the engine vibrates, they can hit each other, creating a loud metallic knock. Gently move the tubes apart with your hands (with the refrigerator turned off and warm) to eliminate contact.
Icing and problems with the defrost system
In systems No Frost the proper operation of the defrost system is critically important. If Heater heating element, the defrost thermostat or timer (electronic module) fails, a coat of ice begins to grow on the evaporator. Over time, the ice blocks the operation of the fan, and it begins to make noise, working “to break.”
In addition, pieces of ice can break off and fall on the rotating parts or simply lie on the bottom of the chamber, creating noise when the floor vibrates. If you notice that the refrigerator began to make noise just after the defrost cycle or, conversely, stopped defrosting automatically, the problem lies in the defrost circuit.
A symptom can also be the whistling of air, which has difficulty making its way through ice-clogged air ducts. In this case, the cold stops flowing into the chamber in the required volume, the compressor works non-stop, trying to gain temperature, which leads to increased energy consumption and noise.
⚠️ Attention: If you find a thick layer of ice on the back wall of the freezer, do not try to pick it out with a knife or sharp objects. Damage to the evaporator channel will lead to freon leakage and costly repairs. Defrost only naturally.
Other mechanical causes of noise
In addition to the main components, noise can also be created by secondary elements. For example, loose compressor mounting bolts or internal lining elements. Over time, vibration loosens connections and plastic parts begin to rattle.
Check the shelves and drawers inside the chambers. If they are not installed tightly or have defects, they may resonate with the frequency of the motor. Take out all the contents and listen to the refrigerator “empty” - this will help localize the source of the sound.
It is also worth inspecting the condenser grille at the back. Sometimes it becomes deformed during transportation and when the motor vibrates, it begins to rattle against the body or wall. Lightly bending the bars of the grille often solves the problem.
Prevention and care of equipment
To extend the life of the refrigerator and maintain silence in the kitchen, regularly carry out preventive maintenance. Once every six months, it is recommended to completely defrost the unit (even the system No Frostto remove hard-to-reach ice and clean the drainage channels.
Keep the rear of the condenser clean: dust and pet hair sticking to the black grille impair heat transfer. This forces the motor to work at its limit, which reduces its life and increases the noise level.
Regular checking of door seals is also important. A loose fit allows warm, humid air to get inside, which provokes increased ice formation and, as a result, problems with the fan and defrosting system.
Why does the refrigerator hum only at night?
At night, the overall noise level in the apartment decreases, and the operation of the refrigerator becomes more noticeable. In addition, at night the voltage in the electrical network often drops, which can cause a change in the tone of the compressor hum. Also, during the day, other devices operate that mask the sound.
Can the noise level depend on the amount of food?
Yes, a full refrigerator is quieter. The products act as heat accumulators and sound absorbers. Empty shelves and drawers can resonate and amplify the sound of a running motor and circulating air.
What to do if the noise does not go away after defrosting?
If complete defrosting (more than 24 hours) does not eliminate the noise, then the problem is of a mechanical nature: wear of the fan bearings, compressor or violation of the geometry of the tubes. Diagnostics with disassembly of the unit is required.
Is it normal for the refrigerator to whistle?
A slight whistle of air in the channels No Frost is acceptable. However, a piercing whistle, similar to the sound of a turbine, indicates that the fan is overloaded due to icing or a faulty bearing.