A sudden loud knocking or hum when starting the refrigerator can scare any owner of household appliances. This sound often indicates that the cooling system is working under increased load or there is a malfunction in the mechanism. You should not ignore such signals, as they can lead to more serious damage and expensive repairs.
Noise at start can be caused by many factors: from a banal misalignment of the case to failure of compressor or the starting relay. In some cases, the device makes sounds due to natural wear and tear of parts, in others it is the result of improper use. Understanding the nature of sound will help you make the right decision: call a technician or fix the problem yourself.
In this article we will analyze in detail the main reasons why The refrigerator turns on loudlyand consider diagnostic methods. You will learn how to distinguish normal operating noise from alarming symptoms and what steps to take to extend the life of your equipment.
Natural causes of noise when starting up
Loud sounds when turned on do not always mean a breakdown. Modern refrigerators, especially models with the No Frostsystem, can make characteristic sounds when the engine starts. Compressor begins to work, creating pressure in the system, which is often accompanied by humming or gurgling. If the sound is quiet and quickly subsides, there is no need to worry.
However, if the noise level has increased sharply compared to the previous operation of the unit, you should listen more carefully. Sometimes the cause is vibration of internal parts or tubes that may come into contact with the housing. It is also worth checking whether the refrigerator is located too close to a wall or furniture, which increases resonance.
It is important to note that in winter, when the oil in the compressor is more viscous, startup may be noisier. This is a normal physical reaction of lubricants to low ambient temperatures. Usually, after several cycles of operation, the noise decreases to the usual level.
Problems with installation and vibration of the housing
One of the most common reasons is why The refrigerator hums loudly when turned on, the installation is incorrect. If the unit is not level, vibration from the running motor is transmitted to the floor and walls, creating the effect of amplified sound. Check the horizontal installation using a building level.
Adjustable legs allow you to set the case perfectly level. If the refrigerator wobbles or one side is raised, this puts additional tension on the system and causes rattling. Also check the distance to the walls: it should be at least 5-10 cm for free air circulation.
Sometimes the source of sound is objects standing on the top panel of the refrigerator or inside it. The vibration can be transferred to bottles, dishes or decorative items, causing them to knock against each other. Remove unnecessary objects and check if the noise has disappeared.
Malfunctions of the starting relay and electrics
If, when turned on, there is a loud click, followed by a hum, and then the refrigerator turns off, the problem most likely lies in starting relay. This element is responsible for starting the compressor engine. If the relay fails, it cannot start the motor correctly, which causes characteristic sounds and network overload.
In some cases, the relay may stick or spark, which is accompanied by a crackling sound. Replacing this part is a relatively simple procedure that you can do yourself if you have the skills to work with electrical appliances. However, if you are not confident in your abilities, it is better to contact a specialist.
You should also pay attention to the condition of the electrical wiring and outlet. Poor contact can cause the plug to hum and become hot. Make sure that the voltage in the network is stable, as power surges can negatively affect the operation of the electric motor.
How to check the relay yourself?
Disconnect the refrigerator from the network, remove the back cover and carefully remove the relay from the compressor. Shake it: if you hear a ringing or knocking inside, it means the part is damaged and requires replacement.
Wear of shock absorbers and compressor bushings
The compressor is attached to the refrigerator frame using special shock absorbers and rubber bushings. Over time, rubber loses elasticity, cracks or completely collapses. As a result, the metal housing of the motor begins to come into direct contact with the frame, transmitting strong vibration and creating a loud knocking sound when starting.
You can diagnose this problem by lightly pressing on the compressor while it is running (being careful!). If the noise changes or disappears, then the problem is in the fasteners. Replacing shock absorbers requires disassembling the rear part of the unit.
Sometimes the cause of knocking is loosening of the bolts securing the compressor itself or the protective casing. (regularly checking) the tightness of the bolts can prevent unpleasant sounds from occurring. Do not forget to disconnect the equipment from the network before any manipulations.
☑️ Diagnostics of the compressor mounting
Hydraulic shock in the cooling system
A loud bang or knocking sound during startup may indicate hydraulic shock. This occurs when liquid refrigerant enters the compressor cylinder instead of its gaseous state. The liquid is incompressible, and its entry into the combustion chamber causes a powerful shock to the piston.
The cause of this phenomenon is often a malfunction of the thermostat or a freon leak, due to which the refrigerant does not have time to completely evaporate in the evaporator. Also, water hammer is possible if the system is not filled correctly or low-quality oil is used.
If you hear such sounds, it is better to stop using the refrigerator until the reasons are determined. Constant water hammer can quickly damage the compressor compressor, which will require an expensive replacement of the unit.
⚠️ Attention: Water hammer is a serious problem that requires professional diagnosis. An independent attempt to repair the refrigerant circulation system without special equipment and knowledge can be dangerous and ineffective.
Table: Types of sounds and their probable causes
To quickly diagnose the problem, we suggest using a table that systematizes the main types of sounds and their possible causes. This will help you navigate the situation before the technician arrives.
| Sound type | Probable cause | Urgency of repair |
|---|---|---|
| Loud hum at start | Wear compressor or relay | High |
| Metal knocking | Destruction of shock absorbers | Medium |
| Gurgling and hissing | Normal circulation of freon | Not required |
| Crackling and clicking | Starting relay malfunction | High |
| Vibration housing | Incorrect installation | Low |
Use this table as a guide, but remember that only a specialist can make an accurate diagnosis after a visual inspection and measurements of system operating parameters.
When it is necessary to call a specialist
There are a number of symptoms in which self-repair not only will not help, but can also aggravate the situation. If refrigerator not only turns on loudly, but also stops freezing, this is a clear sign of a serious malfunction. Also an alarming signal is the heating of the compressor to high temperatures.
If you notice a burning smell, sparking or smoke, immediately unplug the appliance. These symptoms indicate problems with the wiring or motor windings, creating a fire risk. In this case, calling a specialist is required.
In addition, if after all the checks and adjustments the noise does not disappear, but only intensifies, it is better not to risk it. A professional repairman will be able to accurately determine the source of the sound and replace defective parts, guaranteeing further uninterrupted operation of the equipment.