A sudden loud sound, reminiscent of a shot or blow, can scare any owner of household appliances. Popping noises in the refrigerator is a common complaint faced by users of both old and modern models. This sound often occurs when the unit is turned on or off, but can sometimes occur during the cooling cycle. Understanding the nature of this phenomenon is necessary in order to distinguish normal operation from a serious malfunction.
In most cases, sharp sounds are a consequence of physical processes occurring inside the case and do not pose a threat to the safety of food or the device itself. However, there are situations when compressor or the defrosting system requires immediate intervention from a technician. Ignoring alarm signals can lead to costly repairs or complete replacement of the unit. In this article we will analyze in detail the mechanics of the occurrence of sounds and methods for diagnosing them.
It is important to immediately note that the nature of the sound and the moment of its appearance play a key role in determining the cause. A dull crack is different from a loud click, and the frequency may indicate the operation of the timer or thermostat. A critical sign is the combination of cotton with a cessation of cooling or the appearance of a burning smell. If you hear only isolated sounds without accompanying problems, most likely there is no reason to panic.
Physics of the process: thermal expansion of materials
The most common and absolutely harmless cause of strange sounds is the physical change in the size of materials under the influence of temperature. The inner walls of the chamber, the evaporator and even the outer casing are made of plastic, metal and polyurethane foam. When suddenly cooled or heated, these materials contract and expand at different rates, creating tension at the attachment points.
When the temperature difference reaches a critical point, a sharp shift of layers occurs, which our ears perceive as popping or crackling. This is especially typical for new refrigerators that have not yet “got used to” their temperature conditions, or after prolonged defrosting. In such cases thermal expansion is a standard operating process.
The intensity of sounds may vary depending on the quality of the plastic and the thickness of the metal used by the manufacturer. Budget models often make louder noise due to thinner chamber walls. Over time, when internal stresses in materials decrease, the frequency of such pops usually decreases.
If the pops are heard exclusively in the first minutes after turning on the motor or immediately after it stops, then with a 90% probability expansion is to blame plastic. In this case, the housing design simply responds to changing thermodynamic conditions. This situation does not require any repairs, you just need to get used to the acoustic features of your model.
Operation of the No Frost and defrosting system
In refrigerators equipped with the system No Frost, the processes of air circulation and periodic defrosting of the evaporator occur automatically. The cyclical change in temperature conditions here is much more pronounced than in drip systems. The built-in heating element (heating element) is turned on by a timer to melt the ice on the evaporator, which causes a sharp temperature difference.
It is at the moments of transition from the freezing mode to the defrosting mode and back that characteristic clicks and pops are most often heard. The damper or valve switching mechanism may also make sounds if the plastic parts have play. The control system gives a signal and the mechanical parts begin to move, which is accompanied by an acoustic effect.
⚠️ Attention: If the popping noise is accompanied by the smell of burning plastic or burning, immediately unplug the refrigerator. This may indicate a malfunction of the defrost heating element or melted wiring.
The frequency of sounds in No Frost systems depends on the timer settings and the amount of freezing ice. If the chamber is too humid, ice will build up faster and defrost cycles may become more frequent. As a result, the user hears popping sounds more often than usual. Regular maintenance and checking the seals help minimize this effect.
It is important to distinguish between a normal defrost sound and a malfunction. If after the pop the refrigerator continues to freeze, and there is no excess moisture or, conversely, “fur coat” on the walls, then the system is working correctly. Interfering with the operation of electronics unnecessarily can throw off the factory cycle settings.
Problems with the compressor and start relay
The heart of the refrigeration unit is the compressor, and it is often the source of the loudest sounds. When the engine starts, the contacts in the starting relay close, which creates an electric arc and a characteristic click. If the relay is worn or dirty, the sound may become louder and more like a pop.
In more serious cases, a popping sound inside the compressor may indicate water hammer. This happens if liquid freon instead of gaseous freon enters the compression chamber. This phenomenon is extremely dangerous for the integrity of the piston group and can lead to a wedge in the engine. Hydraulic hammer often occurs after improper transportation of the refrigerator or failure to vacuum the system during repairs.
It is difficult to diagnose a problem with the compressor yourself, but you can pay attention to the accompanying signs. If the engine hums louder than usual, vibrates strongly, or fails to start on the first try, making a series of clicking noises, a service call is required. Ignoring these symptoms will lead to burning of the windings.
What is a thermal protection relay?
This is a device that opens the compressor power circuit when it overheats. If the compressor hums and clicks for a long time, but does not start, the protection may be triggered and the relay “knocks out” with a bang.
Modern inverter compressors work differently than classic ones and start smoothly. Therefore, loud pops at start-up are not typical for them. If your inverter refrigerator begins to make such sounds, it is almost guaranteed to indicate an electronic malfunction or mechanical failure.
The influence of refrigerant and pressure in the system
The circulation of refrigerant through the system tubes can also be accompanied by sound effects. In normal mode, freon silently passes from liquid to gaseous state and back. However, if there is air in the system or the pressure balance is disturbed, popping noises may occur.
Gas bubbles passing through a capillary tube or throttle create micro-explosions, which add up to an audible sound. This often happens after poor-quality repairs, when the repairman did not properly evacuate the system before refueling. The air in the circuit not only makes noise, but also reduces the cooling efficiency.
The pressure in the system is a dynamic parameter. If there is a sudden change in the load on the compressor or clogged filter-driers, pressure surges may occur. Condenser tubes, attached to the housing, can jerk and hit the cabinet walls, creating a shock sound.
| Symptom | Probable cause | Urgency of repair |
|---|---|---|
| Single clap at start | Normal relay operation or expansion | Not required |
| Series of clicks without start | Start relay malfunction | Medium |
| Loud bang + no cold | Water hammer or open circuit | High |
| Constant crackling | Thermal expansion or air in the system | Low |
If you notice that oily spots appear on the back grill of the refrigerator after a bang, this is a sign of depressurization. The refrigerant escaped, taking the compressor oil with it. It is strictly prohibited to operate such a unit.
Diagnostics: when a master is needed and when not
In order not to waste money on calling a specialist unnecessarily, carry out the initial diagnosis yourself. Analyze exactly when the sound is heard. If this happens rarely and only when operating modes change, most likely the equipment is working properly. But there are a number of signs that require professional intervention.
Pay attention to the temperature in the cells. If a pop occurs, and after that the food begins to spoil or the freezer stops freezing, the problem is serious. Also an important indicator is the behavior of the compressor: whether it runs continuously or switches off too quickly.
⚠️ Attention: Do not try to open a sealed circuit yourself or change the compressor without special equipment. This requires evacuation of the system and precise dosage of freon.
A specialist will be required if:
- ❄️ Popping noises are accompanied by a complete absence of cold in both chambers.
- ⚡ You smell burning or see sparking in the compressor area.
- 🔊 The sound has become metallic, ringing and repeats every few minutes.
- 💧 A puddle or oil stains have appeared on the floor under the refrigerator.
In most service centers, initial diagnostics are carried out free of charge or for a nominal fee. It is better to overpay for a visit than to buy a new refrigerator to replace the one that burned out due to a minor fault.
☑️ Initial check of the refrigerator
Prevention and proper operation
To minimize the risk of extraneous sounds and prolong life refrigerator, it is important to follow the operating instructions. Correct installation of the unit is the first step towards silence. The refrigerator should stand level, supported on all four legs, so that vibration from the compressor is not transmitted to the body and floor.
Regular defrosting (for drip systems) and cleaning the drainage holes prevents the formation of excess ice. An ice coat on the evaporator not only impairs cooling, but also creates additional stress in the structure, leading to cracking noises during defrosting. Keep equipment clean.
Do not overload the shelves with products. Excess weight can deform the internal partitions, which will make rubbing or popping sounds when thermal expansion occurs. Even distribution of the load helps maintain the geometry of the chambers.
You should also avoid installing the refrigerator near heating devices or in direct sunlight. External heating causes the compressor to wear out, increasing the on and off cycles, which increases the number of sound effects.
Frequently asked questions (FAQ)
Why does the refrigerator slam only at night?
At night the house is usually quieter, and background noise is reduced, so even the usual sounds of appliances operating become more noticeable. In addition, at night the voltage in the electrical network may decrease, which affects the operation of the start relay, making the click louder. The effect of thermal expansion is also affected, when the difference between the temperature in the room and inside the chamber is most noticeable after daytime activity.
Is one loud bang when turning on dangerous?
A single bang at the moment of switching on is, as a rule, not dangerous. This is the sound of the start relay operating or the sudden expansion of the plastic. The danger is a series of pops repeated at short intervals, or a pop after which the refrigerator stops working.
Can an old refrigerator start to pop more loudly?
Yes, over time the plastic dries out and becomes stiffer, which increases the sound of thermal expansion. Compressor parts and the start relay also wear out, making their operation noisier. If the sounds have become annoying, it may be time to replace the worn components.
Does the freon level affect the appearance of pops?
Indirectly - yes. A shortage or excess of freon changes the pressure in the system and the operating modes of the compressor. This can lead to unstable engine starting or water hammer, which sounds like strong blows inside the unit.