The situation when the refrigerator is cracking at the moment the compressor stops is familiar to many owners of household appliances. This sharp, sometimes frightening sound is often perceived as a harbinger of breakdown, but in most cases it does not pose a threat to the functionality of the unit. The physical processes occurring inside the cooling system are inevitably accompanied by sound, the nature of which changes depending on the phase of operation of the motor.
Understanding the nature of the occurrence of these sounds allows the owner not to panic ahead of time and to distinguish normal operation from real problems. Thermal expansion materials are the main factor causing the crackling noise, especially in models with a large number of plastic interior trim elements. However, you should also not ignore changes in the acoustic profile of the device, since sometimes this may indicate wear of the fastening elements.
In this article we will analyze in detail the mechanics of the occurrence of sounds when the compressor is turned off, consider which components produce a characteristic crackling sound and in which cases the intervention of a technician is necessary. You will learn to distinguish the harmless “singing” of plastic from the dangerous symptoms of a malfunction compressor or defrost system.
⚠️ Attention: If the crackling sound is accompanied by a humming sound that does not stop after stopping the motor, or burning smells, you must immediately turn off the power to the device and call specialist.
Physics of the process: thermal expansion of materials
The main reason why refrigerator cracking at the moment of shutdown is a sharp change in the temperature conditions of the materials. The inner chamber and outer lining consist of many layers: metal, plastic, polyurethane foam insulation. When the compressor is operating, the evaporator temperature drops to subzero values, causing compression of the materials, and when it stops, they heat up and, as a result, expand.
The plastic from which the internal panels and shelves are made has a high coefficient of thermal expansion. When the refrigeration cycle is completed and the refrigerant stops circulating, the temperature of the evaporator walls begins to rise. At this moment, a microscopic shift of the layers of plastic occurs relative to each other or relative to the metal frame, which we hear as a loud crackling sound or clicks.
The intensity of the sounds directly depends on the temperature difference and the rate of their change. In modern models, which use thin but durable plastic to improve aesthetics and reduce weight, this effect is more pronounced. Acoustic comfort such models may be lower than those of old Soviet units with thick metal internal chambers, but this is not a manufacturing defect.
It is important to note that if the refrigerator has just been defrosted or a large amount of warm food has been loaded into the chamber, the sounds may be louder and longer lasting. This is due to more intense heat transfer. Thermal deformations in this case, they are reversible and do not affect the tightness of the circuit.
Operation of the No Frost system and dampers
Owners of equipment with the system No Frost they often notice that their devices make specific sounds that are not present in models with a drip system. This is due to the presence of additional mechanical components, such as blowing fans and cold air dampers. When the compressor is turned off, these elements also stop their active phase of operation, which may be accompanied by sounds.
Particular attention should be paid to the air damper. This is a plastic curtain that regulates the air flow from the freezer to the refrigerator compartment. When pressure or temperature changes, the damper drive mechanism may produce a characteristic crackling or clicking sound when returning to its original position. This is a normal situation, indicating the correct operation of the automation.
The fan located behind the back wall can also make sounds when it stops. If it has formed on the blades or axle ice, then when the rotation stops, short-term jamming may occur, accompanied by a crash. However, in good condition, the fan should stop smoothly and silently.
⚠️ Attention: The design of dampers and fans varies from model to model. We recommend that you check the instructions for your device to understand the specifics of the ventilation system.
If the crackling sound comes from the air duct area, check whether the air supply is blocked by products. Impaired circulation can lead to local changes in pressure and temperature, enhancing sound effects during operation dampers.
Features of the compressor and start relay
The heart of any refrigerator is the compressor, and the process of stopping it is also not always completely silent. When the power is turned off, the magnetic field in the motor windings disappears, and the moving parts of the mechanism experience an inertial load. This can cause vibration of the pipelines, which is transmitted to the housing and amplified by resonance.
The starting relay plays a special role. This device is responsible for starting the engine, but even when it is turned off, the relay contacts open. If the relay is mechanical, you may hear a distinct click. In some cases, when the contacts are worn out or the fastening of the relay itself is loosened, this sound can transform into a louder crackling or rattling sound.
| Type of noise | Probable cause | Nature of the sound | Need for repair |
|---|---|---|---|
| Thermal crack | Plastic expansion | Sounding, crackling, series of clicks | No (Normal) |
| Relay click | Opening contacts | Single, dull click | No (Normal) |
| Metal clanging | Vibration of tubes | Humming, turning into clanging | Desirable (fixation of tubes) |
| Loud crackling + buzzing | Compressor malfunction | Loud, rhythmic, long | Yes (Urgent) |
Pipeline vibration is another important aspect. The copper tubes through which the circulation refrigerantcirculates are fixed to the body using special clamps. Over time, the fastenings may become loose, and when the engine is stopped, when the pressure in the system changes and vibration stops, the tubes may briefly hit the cabinet walls or each other, producing a cracking sound.
Why are older refrigerators quieter?
Older models often have thicker walls and lower compressor power, which reduces the overall noise level. In addition, they have fewer plastic elements subject to thermal expansion.
The influence of the quality of installation and alignment
Improper installation of the refrigerator is one of the common reasons for the increase in any sounds, including crackling sounds when turned off. If the device body is skewed, internal stresses in the structure are distributed unevenly. When thermal expansion of the plastic or vibration of the compressor, this can lead to louder sounds of housing deformation.
Checking horizontality is the first step in diagnosis. Use a spirit level or a simple glass of water placed on the lid of the refrigerator. The refrigerator legs should be adjusted so that the door closes on its own when opened slightly. This ensures the correct position of all internal elements.
☑️ Installation diagnostics
It is also important to provide the necessary gap between the back wall of the refrigerator and the wall of the room. If the refrigerator is standing close to each other, the sound wave from the motor running and stopping is reflected from the wall, creating an echo effect and increasing the perceived noise. In addition, insufficient condenser ventilation can lead to overheating and noisier operation of the system.
If the refrigerator is on a slippery floor (for example, linoleum or tile), vibration when the compressor stops can cause microscopic shifts of the entire body, which is also accompanied by the sound of the legs rubbing against the floor. In this case, it is recommended to use special anti-vibration pads under the supports.
When a cracking sound indicates a malfunction
Although in most cases the cracking sound is safe, there are situations when this sound indicates serious problems. If refrigerator cracking not only when stopping, but also during operation, or if the sound has changed its timbre to a more metallic and loud one, this is a cause for concern. It is especially dangerous if the cracking is accompanied by a lack of cold.
One of the possible problems may be a failure of the compressor start relay. If the relay contacts are burnt or stuck, the process of starting or stopping the engine may be accompanied by electrical crackling or sparking. This requires immediate replacement of the relay, since a faulty element can lead to combustion of the compressor windings.
⚠️ Attention: Electrical crackling (sound of spark breakdown) is different from mechanical. It is sharper and may be accompanied by flickering of the light in the room.
Another reason is the destruction of the internal suspension of the compressor. The motor hangs inside the casing on springs. If one of the springs breaks, the motor housing will hit the sides of the casing with each cycle of turning on and off, producing a loud metallic clanging or crackling sound. This requires replacing the compressor or complex repairs.
It is also worth paying attention to the condition of the evaporator. If a large one has formed in the system (which happens when the defrosting heating element in No Frost malfunctions), then when the compressor stops and the pressure changes, the crack of breaking ice can be very loud. In this case, the refrigerator stops freezing, and defrosting and repair of the defrosting system are required. ice blockage (which happens when the defrosting heating element in No Frost malfunctions), then when the compressor stops and the pressure changes, the crack of breaking ice can be very loud. In this case, the refrigerator stops freezing and the defrosting system needs to be defrosted and repaired.
Methods for diagnosing and eliminating noise
In order to accurately determine the cause of the noise, you can conduct independent diagnostics. First of all, try pressing your hand against the back wall of the refrigerator or the side panels at the moment when the cracking noise is heard. If the sound stops or changes tone, then the problem is vibration of the panels or loose trim elements.
Check the internal contents. Remove all food and shelves, leaving the chamber empty. Start the refrigerator and listen. If the crackling noise disappears, it means that some objects or the structure of the shelves resonated. Often plastic containers, when they come into contact when cooling, make sounds similar to the crackling sound of the unit itself.
Testing algorithm:1. Disconnect the refrigerator from the network.
2. Inspect the back wall for contact with the tubes.
3. Check the compressor fastening (you need to remove the back cover).
4. Turn on and listen to the operation cycles.
If you find that the tubes on the back wall are in contact, you can carefully (being extremely careful not to damage!) separate them or place a piece of foam rubber between them. However, it is better to entrust this procedure to professionals, since inept handling of copper tubes can lead to depressurization of the circuit and leakage freon.
Is it possible to lubricate the rubbing parts?
It is impossible to lubricate the rubbing plastic parts inside the refrigerator with ordinary oils - they can be toxic if in contact with food or damage the plastic. Use only special silicone lubricants that are safe for the food industry, and only for damper mechanisms, without touching the food.
Prevention and care of equipment
To minimize sound effects and extend the life of the refrigerator, it is important to follow the operating rules. Regular defrosting (for drip systems) and de-icing (for No Frost) prevents the formation of ice plugs that can crack due to temperature changes. The cleanliness of the condenser on the rear wall also affects the operating modes of the compressor.
Do not overload the refrigerator shelves. Excess weight can cause deformation of plastic parts, which will produce louder sounds when thermal expansion occurs. Even distribution of food helps maintain balance and reduces stress on the structure.
Check the door seal periodically. If the seal is worn or dirty, warm, moist air enters the chamber, which leads to increased frost formation and more frequent compressor cycles, which means more frequent sounds when it stops.
Maintaining the temperature regime in the room where the refrigerator is installed also plays a role. If the room is too hot, the compressor works harder, heats up more, and the temperature difference when it stops will be sharper, causing a loud cracking sound in the plastic.
Frequently asked questions (FAQ)
Why does a new refrigerator crack more than an old one?
Modern models often use thinner and lighter materials for the interior finishes and also have more powerful direct drive compressors. The plastic in new units may be more rigid, which makes the sounds of thermal expansion louder and more noticeable. In addition, the absence of a thick layer of sound insulation in order to increase the useful volume also affects the acoustics.
Is it dangerous if a cracking sound is heard every 15 minutes?
If the crackling occurs strictly when the compressor stops (the operating cycle of which can be 15-20 minutes depending on the load and temperature), then this is normal. However, if the refrigerator turns on and off too often (the so-called “short cycle”), this may indicate problems with the thermostat or a freon leak, which requires diagnosis.
Can the ice inside the refrigerator crack?
Yes, absolutely. Ice may form in the freezer compartment or on the evaporator behind the rear panel. When the temperature changes (for example, when a door is opened or a defrost cycle), the ice expands or contracts, cracks, and makes loud noises like gunshots or loud cracking noises. This is a physical property of water and ice.
Do you need to call a technician if the refrigerator is just cracking?
If the crackling noise is heard only when the motor is stopped, the refrigerator freezes well, and there is no frost or oil on the back wall, calling a technician is most likely not required. This is the normal work of materials. A technician is needed if the cracking sound is accompanied by loss of cold, the appearance of puddles under the refrigerator, or a burning smell.
Does the brand of the refrigerator affect the noise level?
Yes, different manufacturers use different technologies and materials. For example, refrigerators Liebherr or Bosch are often praised for their quiet operation thanks to high-quality compressors and good insulation. Budget models may be noisier due to less advanced design and materials. However, even expensive equipment can make sounds of thermal expansion.