The situation when the refrigerator stops cooling, and the food inside quickly deteriorates, always takes you by surprise. Often the source of the problem is compressor, which either does not turn on at all, or makes strange sounds and immediately stalls. Understanding the causes of such a malfunction will help you save time on calling a technician or, in the best case, fix the breakdown yourself.
In this article we will analyze in detail the mechanics of the “heart” of your refrigerator and the main factors leading to its stoppage. You will learn how to distinguish a trivial power surge from serious mechanical wear, and understand when repairs make sense, and when it is easier to buy new equipment.
Do not panic ahead of time: sometimes the unit is silent due to triggered protection or malfunction of adjacent components. Competent diagnostics begins with an analysis of symptoms, so listen carefully to the operation of the household appliance before you grab tools.
Main signs of a compressor malfunction
The first alarm signal should be a change in temperature. If the chamber becomes warm and the food begins to thaw, but you do not change the thermostat settings, it means that the cooling cycle is broken. The compressor can behave differently: hum and not start, turn on for a couple of seconds and turn off, or simply remain silent, even when the light is on. Pay attention to the motor itself. In normal operation, it heats up, but if it is hot to the point where it is impossible to touch it, or, conversely, absolutely cold when the power is turned on, this is a clear sign of pathology. Also an alarm bell is the appearance of a burning smell or melted insulation.
Please note casing temperature the motor itself. In normal operation, it heats up, but if it is hot to the point where it is impossible to touch it, or, conversely, absolutely cold when the power is turned on, this is a clear sign of pathology. Also an alarming bell is the appearance of a burning smell or melted insulation.
⚠️ Attention: If you smell burning wiring or see sparking in the motor area, immediately turn off the power to the refrigerator. Further operation may lead to a short circuit or fire.
Another important symptom is the nature of the sound when trying to start. If you hear a loud click, followed by a hum that lasts 5 to 10 seconds, and then a click that fades, the starter is trying to start a seized or overloaded engine. In normal mode, operation piston unit should be relatively quiet and smooth, without jerks and vibrations.
Problems with power supply and starting relay
The most commonplace, but often ignored reason is the lack of normal voltage in networks. If the voltage in the outlet “jumps” or is below 190 Volts, a modern inverter or classic motor simply will not be able to start, going into protection. Check the outlet by connecting another device to it, for example, a lamp or hair dryer.
Often the culprit is silence starting relay. This small device is responsible for supplying a starting pulse to the motor winding. If the contacts inside the relay are oxidized or burned, the circuit will not close. In old models, relays can be electromagnetic, in new ones - posistor, and each has its own life cycle of switching cycles.
- 🔌 Oxidation of contacts: Over time, the metal is covered with an oxide film, increasing the resistance.
- 💥 Voltage surge: A sharp change in the network could damage the relay coil or the posistor itself.
- 🔨 Mechanical wear: The moving parts of the relay could simply get stuck or crumble from old age.
To check the relay, it must be removed and shaken. If you hear a rattling noise inside, it means the mechanical part is damaged. You can also test the contacts with a multimeter: in normal condition, the resistance should be close to zero (for closed contacts) or infinity (for open ones), depending on the type of device.
Malfunctions of the thermostat and sensors
The compressor will not work if the “brain” of the refrigerator does not give it such a command. Responsible for this is thermostat (in mechanical models) or electronic temperature sensor (in models with No Frost and inverter control). If the thermostat is faulty, it may “think” that there is already cold arctic frost in the chamber and does not close the motor power supply circuit.
In mechanical thermostats, the capillary tube often breaks or the bellows seal is lost, filled with freon. In electronic systems, sensors may give incorrect readings due to contamination or an internal break. You can check a mechanical thermostat by closing its contacts directly: if the motor hums, the problem is in the regulator.
It is important to consider that in modern models with the system No Frost a control module that reads data from several sensors may be responsible for the operation of the compressor. If one of them, for example, a defrost sensor, shows an error, the system can block the start of the refrigeration cycle to avoid freezing of the evaporator.
How to check the thermostat with a multimeter?
Unplug the refrigerator. Remove the thermostat and immerse its sensing tube in cold water with ice. Ring the contacts: when cooled they should open (infinity resistance), and when heated in the hands they should close (resistance 0 Ohm).
Mechanical wear and jamming of the piston group
The most serious and expensive problem is physical damage to the internal mechanisms. A compressor is a complex mechanism where pistons move at high speed. Lack of lubrication, moisture getting into the system, or simply running out of service life leads to the fact that the parts begin to rub against each other with enormous force.
When this happens jamming, the engine tries to turn the shaft, consumes colossal current, but cannot move the pistons. At this moment, the thermal protection relay is triggered and the unit is turned off. Repeated attempts to start in this mode only finish off the motor windings, causing them to overheat and turn-to-turn short circuits.
There is a method of “wedging” by applying increased voltage, but it is extremely risky and often gives only a temporary effect. If the compressor is jammed, most often it requires a complete replacement, since repair at home is impossible, and in a workshop it will cost almost the cost of a new unit.
| Symptom | Probable cause | Difficulty of repair |
|---|---|---|
| Humming 5-10 seconds and clicks | Stuck or faulty relay | Medium/High |
| Silent, lamp on | Thermostat, wiring, control module | Low/Medium |
| Works, but does not cool | Freon leakage, valve wear | High |
| Strong vibration and noise | Destruction of the motor mount | Average |
Refrigerant leakage and impact on engine operation
Many do not know that the lack of freon can also cause the compressor to stop. In modern systems, the refrigerant not only cools, but also removes heat from the motor windings. If a leakageoccurs, the motor begins to idle, overheats and goes into temperature protection.
In addition, in an inverter-controlled system, pressure sensors can block the start if they see that the circuit is empty. This is done to prevent dry operation, which would instantly damage the compressor. Signs of a leak are a swollen rear radiator or oily spots (oil smudges) at the joints of the tubes.
Adding freon “by eye” without finding and eliminating the leak is pointless. The gas will still leave, and the compressor will continue to operate in emergency mode. Requires professional vacuumization of the system, soldering and filling strictly by weight.
Inverter compressors: diagnostic specifics
Owners of refrigerators LG, Samsung, Bosch and other brands often encounter inverter models. They differ in that they do not turn off completely, but smoothly change speed. If such a compressor does not work, the problem is rarely mechanical - most often the electronic control module (inverter board) fails.
Diagnostics of inverters requires special equipment. It is difficult to check the presence of pulses on the windings with a conventional multimeter. The error is often coded by blinking indicators on the front panel. For example, a series of 7 flashes may indicate a communication error between the main board and the inverter board.
⚠️ Attention: Inverter compressors are very sensitive to voltage quality. If the lights in your house flicker frequently, be sure to use a stabilizer, otherwise the motor electronics will burn out in the first jump.
A common mistake is to try to replace a conventional compressor with an inverter one without replacing the control board. This is technically impossible, since the principles of their operation are radically different: one operates from 220V, the other from a converted three-phase current with variable frequency.
☑️ Primary diagnostics of the compressor
Is it possible to restore the compressor yourself?
The answer to this question depends on the type of fault. Any person with minimal skills and a screwdriver can replace the start relay, thermostat or clean the contacts. These parts are consumables and do not require opening the freon circuit.
However, if we are talking about replacing the compressor itself, the situation changes. This requires:
- 🔥 Gas burner: For soldering copper tubes.
- 🧊 Vacuum pump: To remove moisture and air from the system.
- ⚖️ Scales and freon: For filling precise dose of refrigerant.
Without evacuation, moisture will remain in the system, which, when frozen, will turn into an ice plug that clogs the capillary, or will react with the oil, forming acid. Therefore independent replacement of the compressor without equipment for charging freon is doomed to failure..
If you decide to replace, be sure to use a compressor of the same power and refrigerant (R134a, R600a) as the original. Installing a more powerful motor “just in case” will lead to frequent starts and rapid wear, and a less powerful one will lead to insufficient cooling.
Frequently asked questions (FAQ)
Why does the compressor turn on for 10 seconds and turn off?
Most likely, the thermal protection relay is triggered. Reasons: jamming of the piston group, an interturn short circuit in the motor winding, or a malfunction of the starting relay, which cannot provide the necessary impulse to start.
Can a compressor burn out from a power surge?
Yes, this is one of the most common reasons. A sudden voltage surge can break through the insulation of the windings or damage the electronic control board (in inverter models). It is recommended to use surge protectors or stabilizers.
How to understand that it is the compressor that has burned out, and not the relay?
You need to ring the motor windings with a multimeter. If the resistance between the contacts is infinite (open) or close to zero (short circuit), the motor burns out. If the resistance is normal (usually 10-30 Ohms), but the motor does not start, the problem is in the relay or mechanical jamming.
Is it worth changing the compressor in an old refrigerator?
It is economically feasible only if the refrigerator belongs to the premium segment or has other expensive components in perfect condition. In old budget models, the cost of a new compressor and the work to replace it often exceeds the residual value of the appliance.