The situation when a working refrigerator suddenly goes silent, and at this moment there is a strong blow or roar that can scare any owner. This sound often resembles the fall of a heavy object or a strong metal clang, which makes you think about a serious breakdown of the unit. Most often, this sound is associated with physical processes occurring inside the compressor or in the engine starting system when it stops.
Understanding the nature of this sound is not just satisfying curiosity, but a necessary measure to extend the service life of the equipment. Sharp vibrations and shocks when stopping can indicate both banal instability of the housing and critical wear of the internal parts of the engine. Ignoring the problem can lead to the fact that a quiet knock will turn into a complete inoperability of the device.
In this article we will analyze in detail the mechanics of the process of stopping the compressor, consider typical malfunctions and help you determine whether the intervention of a specialist is required or the situation can be corrected yourself. Diagnostics by ear - important a skill that will allow you to save time and money.
Physics of the process: why a shock occurs when stopped
To understand the cause of the rumble, you need to understand how exactly the compressor works. This is a sealed pump that pushes refrigerant through a system of pipes. Inside the metal housing (casing) there is a motor suspended on springs. When you hear the command from the thermostat to stop, electrical current stops flowing to the windings and the motor rotor suddenly stops rotating.
At this moment of inertia, several things can happen. Firstly, the engine itself, swinging on springs, can jerk by inertia and hit the walls of the casing if shock-absorbing springs they are stretched or come off. Secondly, high pressure remains inside the system, which, when the valves are suddenly closed, creates a hydraulic shock that is transmitted to the housing.
It is also worth considering the operation of the starting relay. This device is responsible for starting and stopping the motor. If the relay contacts stick or open with a delay, this causes a spark to jump and a characteristic click, which in a quiet room can be perceived as a loud blow. Normal operation the compressor implies a quiet hum and a barely audible click when turning off, but not a loud clang.
⚠️ Attention: If the roar is accompanied by sparking in the rear wall area or a burning smell, immediately unplug the device. This may indicate a short circuit in the start relay or motor windings.
The main reasons for loud sounds when turning off
There are a number of specific technical malfunctions that provoke the appearance of loud sounds. The first and most common cause is wear or damage to the compressor suspension. The springs on which the motor hangs lose their elasticity or rust over time. As a result, when stopping, the engine makes too large an amplitude of oscillations and hits the inner walls of the casing.
The second reason lies in the start-protection relay. If the contact opening mechanism is broken, the relay may “shoot” with a characteristic loud click. This often happens in older refrigerator models that use relays with a heavy core. Modern electronic relays are quieter, but they are not immune to breakdowns.
The third reason is an imbalance of the refrigerant or a clogged capillary tube. When excess pressure or, conversely, vacuum occurs in the system, the process of stopping gas circulation becomes turbulent. Liquid freon can hit the walls of the tubes, causing ringing and rattling, which is transmitted to the housing.
- 🔨 Mechanical wear motor suspension (springs, shock absorbers).
- ⚡ Malfunction or wear start relay (loud opening of contacts).
- 🌪️ Water hammer in the circulation system due to excess or lack of refrigerant.
- 🔩 Loosening of mounting bolts the compressor itself or the protective casing.
Diagnostics of the condition of the compressor and suspension
To accurately determine the cause of the noise, it is necessary to conduct a visual and acoustic inspection of the rear of the unit. Remove the back panel (if there is one) or simply get to the compressor. Pay attention to how the motor hangs. It should not touch the casing walls in any position. If you see that one of the springs is stretched more than the others or has come off completely, the cause of the noise has been found.
Check the mounting bolts that attach the compressor to the frame of the refrigerator. Prolonged vibration may cause them to weaken. In this case, when the engine stops, the entire structure will shift with a characteristic metallic knock. Use an appropriately sized wrench to check the tightness of all visible connections.
It is also worth paying attention to the condition of the pipes leaving the compressor. They should not touch each other or the cabinet walls. When the engine operates and stops, the tubes vibrate, and if they are not secured correctly, this knock will intensify. Vibration of the tubes is a frequent companion to loud stops.
| Type of sound | Probable cause | Difficulty of repair | Required tools |
|---|---|---|---|
| Thud metal impact | The engine hits the casing | High | Set of keys, pliers |
| Audible click | Start relay | Medium | Screwdriver, multimeter |
| Rattling of tubes | Touch tubes against each other | Low | Hands, possibly clamps |
| Case vibration | Loose motor fasteners | Low | Wrench |
The role of the starting relay in the occurrence of noise
The starting relay is a small black or white block that fits onto the side fitting of the compressor. Its task is to supply a powerful current pulse to start the engine and turn off the starting winding after gaining speed. If the mechanism inside the relay is worn out, the process of opening the contacts may be accompanied by a loud bang.
This is especially common in induction-type relays. Inside them there is a movable core, which, under the influence of current, rises and closes the contacts. When turned off, it falls, and if the seat is broken or the mechanism jams, a knock is heard. Replacing such a relay is a simple procedure, but it requires precise selection of the model for your compressor.
In some cases, the relay may “stick”. Then the compressor hums, but does not start, and then the protection switches off with a bang. This is accompanied by a very loud clicking sound. If you observe such a picture, you cannot continue operating the refrigerator - the motor may burn out.
How to check the relay without replacing?
Remove the relay and shake it near your ear. If you hear the sound of broken parts or knocking inside, the relay is faulty. You can also ring the contacts with a multimeter: in normal condition, the resistance should be close to zero or infinity, depending on the type of contacts.
The influence of installation and external factors
The cause of the rumble does not always lie inside the mechanism. Very often, users forget about the rules for installing equipment. If the refrigerator is not level, the load on the compressor is distributed unevenly. When stopped, the misalignment increases the inertial impact, and the sound becomes much louder.
Check the adjustment supports at the bottom of the refrigerator. They must be unscrewed so that the device stands stable and does not wobble when pressed on the corner. Use a building level to check levelness. Even a slight misalignment can cause resonance.
It is also worth checking the distance to walls and furniture. The rear wall of the refrigerator may vibrate when operating and stopping. If it is pressed closely against a wall or cabinet, the vibration is transmitted to them, amplifying the sound. Leave a gap of at least 5-10 cm for free air circulation and vibration damping.
☑️ Checking the installation of the refrigerator
When you need to call a specialist
There are situations when self-repair not only will not help, but it will also do harm. If after checking the fasteners and installation the problem persists, most likely the problem is in the internal components. Opening the compressor casing at home is strictly prohibited, since the oil and refrigerant are under high pressure there.
If you hear a rumble and the refrigerator has stopped freezing or is freezing weakly, this is a sign of a serious breakdown. The piston rod or valves inside the compressor may have broken. In this case compressor repair is impractical, its complete replacement is required.
A master is also needed if the problem is related to freon leakage. The noise may be due to the fact that there is little gas left in the system and the compressor is running dry or overheating. For diagnostics and refueling, special equipment and a license are required.
⚠️ Attention: Never try to solder refrigerator tubes or open the sealed compressor casing yourself. This is life-threatening and requires professional equipment for vacuuming and filling the system.
Prevention of noisy operation of equipment
To avoid unpleasant sounds in the future, it is important to regularly carry out preventive maintenance. Once every six months, it is recommended to move the refrigerator away, wipe the rear grill from dust and check the tightness of the tubes. Dust on the condenser causes the compressor to work longer and harder, which accelerates wear on the suspension.
Watch what you put on top of the refrigerator. Heavy objects can create additional vibration, which is transmitted to the compressor housing. It is also not recommended to install the refrigerator in niches without an air gap, since overheating accelerates the aging of rubber and metal parts.
Regularly check the integrity of the door seals. If the door does not close tightly, the compressor turns on more often, the number of start-stop cycles increases, which directly affects the wear of the start relay and shock absorbers. Caring for the seal This is also a concern for the quiet operation of the unit.
How to extend life compressor?
Do not load a lot of warm food into the refrigerator at once. A sharp increase in temperature forces the motor to work at its limit, which increases the load on the starting system and can lead to loud stops due to overload.
Is it possible to completely remove the rumble when stopping?
It is impossible to completely remove the sound of a stop, since this is a physical process. However, you can make it quiet and unnoticeable. If the rumble is strong, then there is a malfunction (wear of springs, relays) that needs to be eliminated. After the repair, the sound will become a normal quiet click.
Is it dangerous to operate a refrigerator with a loud knock?
For a short time - not dangerous, but undesirable. Constant impacts can lead to destruction of the internal motor mount, broken tubes inside the casing, or failure of the start relay. This can result in an expensive replacement of the compressor.
How much does it cost to replace the start relay?
The relay itself is inexpensive, usually several hundred rubles. However, if you call a specialist, the price will increase due to the cost of travel and work. Self-replacement is possible if you know how to use a screwdriver and know the model of your refrigerator.
Why does a new refrigerator stop loudly?
New equipment can be “noisy” during the first days of operation due to the grinding in of parts. Also check that all shipping bolts and films have been removed. If the noise is very strong immediately after purchase, this may be a defective installation or a defect in the compressor - contact the warranty service.