A sudden knock or hum in a working refrigerator can turn a quiet evening into a real test for the nervous system. This sound often occurs unexpectedly and can be either a sign of normal wear and tear on parts or a symptom of a serious breakdown that requires immediate attention. Understanding the nature of noise is the first step to preserving expensive equipment and products.
A refrigeration unit is a complex system where each element performs its own function, and disruption of one unit inevitably affects the overall sound background. Compressorbeing the heart of the system, during operation it emits a characteristic even hum that should not cause alarm. However, if metallic blows, rattling or rhythmic clicks are added to this hum, it becomes impossible to ignore the situation.
In this article we will analyze in detail why the motor in the refrigerator knocks, which components most often fail and whether it is possible to fix the problem yourself. We will look at the mechanical, electrical and structural causes of extraneous sounds so that you can accurately diagnose the problem.
Natural causes of noise and features of the compressor
Before you panic and look for a service center number, it is important to understand that not all sounds are a sign of a breakdown. Modern refrigerators, especially models with the No Frostsystem, are equipped with many moving elements and fans. Refrigerantcirculating through the tubes can also create sounds resembling gurgling or a slight hiss, which is absolutely normal.
Knocking when starting or stopping the engine often associated with inertial processes. At the moment of switching on, the compressor rotor overcomes the static resistance, which may be accompanied by a short-term shock. If the sound is quiet and occurs only in the first seconds, this may be a feature of the operation of piston group a specific model.
However, if the knocking becomes loud, rhythmic or changes its tone depending on the mode operation, it is worth listening more carefully. Inverter compressors, for example, they work differently than linear ones and make less noise, but if the electronics malfunction, they can buzz or click. It is important to be able to distinguish between operating noise and alarm signal.
Mechanical faults: wear of parts and fasteners
The most common reason why the motor in the refrigerator knocks is physical wear of internal components or a violation of their fixation. Over time, the vibration that occurs during engine operation weakens the bolted connections. Suspension springson which the compressor is attached may lose their elasticity or burst, which is why the metal casing begins to beat against the housing.
Inside the compressor itself there are tubes through which freon circulates. If these tubes are located too close to each other or to the walls of the housing, they begin to collide when vibrating. This creates a characteristic metallic ringing or knocking sound. To eliminate such a problem, it is often necessary to carefully straighten the tubes, increasing the gap, but this must be done extremely carefully so as not to damage the system.
⚠️ Attention: Any manipulation of the copper tubes of the refrigeration circuit requires extreme caution. Damage to the tube will lead to freon leakage and will require expensive refilling and soldering in the service.
Another common reason is wear bearings or the engine shaft bushings. When the lubricant dries out or becomes contaminated, metal parts begin to rub against each other “dry,” producing grinding and knocking noises. In advanced cases, the shaft may receive play, which will lead to the rotor beating on the stator.
- 🔨 Loosening the bolts: Check the fastening of the compressor to the frame; often it is enough to simply tighten the nuts.
- 🔧 Deformation of tubes: Vibration could displace copper lines, causing them to collide.
- 📉 Wear of shock absorbers: Rubber feet or motor suspension springs could dry out or burst.
☑️ Diagnostics of mechanical reasons
Electrical problems: starting relay and windings
If mechanical damage is excluded, the cause of the knocking may lie in the electrical filling. The key element here is starting relay. It is this that gives the impulse to start the engine. If the relay is faulty, the contacts may stick or open with a characteristic loud click, and the motor itself may try to start and stall, making a humming sound.
Frequent clicks with a frequency of several seconds or minutes indicate that the compressor cannot start and the thermal relay protects it from overheating. In this case, motor windings may be partially damaged (interturn short circuit), or the voltage in the network is not enough for a reliable start.
It is also worth paying attention to the condition of the wiring. Poor contact in the terminal block can cause sparking and crackling noises. This not only creates noise, but also poses a real fire hazard. Capacitor, which helps in the operation of the engine, when swelling or breakdown can also make sounds, although more often it simply stops performing its function.
| Symptom | Probable reason | Required action |
|---|---|---|
| Loud click and silence | Faulty starting relay | Replacing the relay |
| Humming, but does not start | The compressor is jammed or the windings are broken down | Diagnostics of the motor-compressor |
| Crackling and sparking | Poor contact in the wiring | Cleaning and tightening contacts |
| Rhythmic clicks | Thermal relay activation | Checking voltage and windings |
How to check the start relay yourself?
Remove the relay from the compressor and shake him. If you hear the sound of broken glass or a loose weight inside, the Relay is faulty and needs to be replaced. Visually inspect the contacts for carbon deposits.
The influence of incorrect installation on the noise level
Often the answer to the question “why the motor is knocking” lies not in the motor itself, but in how the refrigerator is installed. If the device is not level, a misalignment occurs, which leads to uneven distribution of the load on the compressor. This causes increased vibration and knocking of the case against internal elements.
Check the legs of the refrigerator. They should fit snugly on the floor, but still allow you to adjust the level. Use a building level to check for levelness. If the floor is uneven, be sure to use the adjustment screws to compensate for height differences.
⚠️ Attention: The back wall of the refrigerator should not be flush against the wall. A minimum gap of 10-15 cm is necessary for free air circulation and heat removal from the condenser, which also reduces the noise level.
In addition, it is worth checking whether the internal shelves or products are touching the chamber walls during vibration. Sometimes a sound that seems like a motor is actually the rattling of dishes or bottles sitting on the door or shelves. Make sure that all contents are fixed.
When a knock indicates a critical breakdown
There are situations when the knock of the motor is a harbinger of a complete stop of the refrigerator. If you hear dull, heavy knocks inside the compressor housing, this may indicate destruction of valve group or the piston system. In this case, pressure is not created in the system, and the cold ceases to be produced.
Another alarming sign is a change in the color of the oil or the appearance of a burning smell in combination with noise. This indicates that the motor is operating in extreme mode, possibly due to a (clog) in the system or a freon leak, which causes it to work without stopping. Overheating in this case, it is inevitable.
If the refrigerator starts knocking after defrosting or a power surge, there is a possibility of serious damage high. In such cases, self-repair can be not only useless, but also dangerous. It is better to contact specialists for professional diagnostics.
- 🚫 Lack of cold: There is a knock, but the refrigerator does not freeze - a sign of compressor destruction.
- 🔥 Heating housing: If the motor is hot to the touch and knocking, a wedge is possible.
- ⚡ Knocking out the plugs: The knocking is accompanied by the activation of circuit breakers in the panel.
Methods for eliminating knocking: safety instructions
If you decide to eliminate the cause of the knocking yourself, strictly follow safety precautions. The first and main rule: any work inside the refrigerator body related to the electrical or mechanical aspects of the compressor is carried out only when completely turned off the device is plugged in.
First, try to find the source of the sound. Remove the rear protective panel. Turn on the refrigerator and carefully (without touching live parts!) try to detect vibration with your hand. If the tubes are knocking, you can carefully bend them with a plastic spatula or a gloved hand, increasing the gap.
Procedure for replacing the start relay:1. Disconnect the refrigerator from the network.
2. Remove the back cover.
3. Remove the plastic casing from the compressor.
4. Disconnect the wires from the old relay.
5. Remove the relay from the compressor contacts.
6. Install a new relay (strictly according to the markings).
7. Connect the wires and reassemble everything in the reverse order.
If the problem is in the motor mounting, you may need to replace the rubber shock absorbers or simply tighten the bolts. Sometimes placing an additional layer of vibration-isolating material under the motor helps, but this is a temporary measure. The main thing is to ensure rigid and even fixation of the unit.
Is it possible to lubricate a compressor?
Modern compressors are sealed units. It is impossible to add oil or lubricant to them without opening the housing and breaking the seal, which will lead to damage to the unit.
Prevention and care of the refrigeration unit
To avoid knocking and prolong the life of the motor, it is necessary to ensure correct operating conditions. Regularly clean the condenser (grid at the back) of dust and animal hair. A capacitor clogged with dust causes the motor to work with overload, which accelerates wear of parts.
Do not overload the refrigerator with food and make sure that it does not work non-stop due to a loose door or a faulty seal. Constant operation without stopping is a sure way to rapid failure of piston group and the appearance of knocking.
⚠️ Attention: Specifications and maintenance requirements may vary depending on the model and year of manufacture. Always check the official instructions of the manufacturer of your device before starting any work.
Timely defrosting (for drip systems) is also important