The situation when you open the refrigerator, and it’s warm and quiet inside, always takes you by surprise. The absence of the usual hum of the motor and light in the chamber is the first alarm signal indicating that the cooling cycle has been interrupted. In most cases silence is the culprit it is the compressor that, for some reason, refuses to start. This can be either a trivial power surge or a serious breakdown of the electrical circuit.
Before you panic or call a technician, it is important to conduct an initial diagnosis to understand the scale of the problem. Often malfunction hidden in simple elements, the replacement of which does not require deep knowledge of electrical engineering. However, ignoring the symptoms can lead to food spoilage and costly repairs to the entire cooling system. In this article we will analyze in detail why the compressor does not turn onhow to check the main components and whether it is possible to restore the operation of the unit yourself.
It is worth understanding that modern models, be it Indesit, Bosch or LG, have a similar logic of the trigger mechanism. Differences may only relate to the design of the relay or the type of motor, but the principle of troubleshooting remains universal. Your task is to use the method of elimination to determine which element has ceased to perform its function. Let's start with the simplest and gradually move on to complex diagnostics.
Primary check of the power supply and socket
The most commonplace, but often ignored reason is the lack of voltage in the network. If the refrigerator is not humming and the indicators do not light up, the problem may not be in the equipment at all. First of all, check that the plug is firmly inserted into the outlet. Sometimes, due to vibration during operation, the contacts become loose and the power is lost. You should also make sure that the outlet itself is working by connecting another powerful device to it, for example, a hairdryer or kettle.
Pay attention to the condition of the power cord. If there are animals in the house or the wire is pinched by furniture, internal breakdown of the core is possible. Visually, the insulation may look intact, but there will be no contact. Try gently moving the wire at the base of the plug and at the entrance to the refrigerator body. If at this moment you hear a crackling sound or the unit tries to turn on, it means open circuit the cable is located.
⚠️ Attention: Before any manipulations with the electrical components of the refrigerator, be sure to disconnect it from the network! Working under voltage is dangerous and can result in a short circuit.
If you have a surge protection system or stabilizer installed, check its indication. Perhaps the fuse has tripped or the device has gone into protection mode. In older houses, the cause may be poor contact in the distribution box or panel. Make sure that the automatic switch on the kitchen line has not been knocked out.
Faults in the starting relay and thermal protection
If there is power, but the motor is silent, the next candidate for checking is starting relay. This small block is responsible for starting the engine and turning off the starting winding after gaining speed. It is the relay that often makes a characteristic click when trying to start, followed by silence. Inside the relay body there is a coil and contacts, which can burn or oxidize over time.
Near the relay there is often a thermal protection (thermal relay). Its task is to break the circuit when the compressor overheats. If the bimetallic plate inside the protection is deformed or the contacts are stuck open, the current simply will not reach the motor windings. Checking these elements requires removing the back cover at the bottom of the refrigerator and removing the casing from the motor.
- 🔍 Visually inspect the relay body: the presence of melting, blackening or cracks indicates the need for replacement.
- 🔊 Shake the relay next to your ear: if you can hear the sound of broken glass or dangling parts, the mechanism is destroyed.
- ⚡ Test the contacts with a multimeter: the resistance should be either zero (closed) or infinite (open) depending on the type.
Often owners try to clean the relay contacts with sandpaper. This is a temporary solution that can help start the refrigerator for a couple of days, but the reliability of such work is questionable. It is better to immediately replace the unit with a new one, choosing an analogue according to the markings. For different brands, such as Atlant or Stinol, different types of starters are used (RT, RZ, PTC).
Problems with the thermostat and temperature sensors
The thermostat (thermostat) is the “brain” that commands the compressor to turn on when the temperature in the chamber rises above the set one. If this element fails and opens the contacts forever, start signal it simply does not work. In mechanical models, this is a simple “twist” with a capillary tube; in electronic models, it is a digital sensor.
To check a mechanical thermostat, you can close its contacts directly, eliminating it from the circuit. If after this procedure the compressor starts working, it means the regulator is faulty. In models with a system No Frost and electronic control, the defrost or evaporator sensors often burn out, which blocks the operation of the entire system. The electronics perceives incorrect readings as an emergency and does not allow the engine to start.
Symptoms of a malfunctioning thermostat can be different:
- 🌡️ The refrigerator does not turn on at all, although it is warm in the chamber.
- ❄️ The unit works non-stop, without turning off (if the contacts are stuck).
- 🔌 The compressor starts for a few seconds and stalls (rarely, but happens when there is a short circuit in the sensor circuit).
Replacing the thermostat in mechanical refrigerators (Biryusa, Oka) usually does not cause difficulties. You just need to correctly install the capillary tube in the seat. In electronic models (Samsung, LG), replacing sensors requires disassembling the internal panel and sometimes flashing or resetting errors through the service menu.
How to check a thermostat with a multimeter?
To check, remove the thermostat and immerse its sensitive part (capillary) into cold water with ice. Ring the contacts: in the cold they should open (resistance is infinity), and in the heat they should close (resistance is close to 0). If there is no contact in the heat, the thermostat needs to be replaced.
Diagnostics of the compressor itself and windings
The most unpleasant scenario is failure of the very heart of the refrigerator, compressor. If all the previous elements are working properly, and the motor hums but does not start, or is completely silent when voltage is applied, the problem may be in the motor windings. Inside the motor there are starting and working windings, as well as a common terminal. If the insulation is broken down or the wire is broken, the engine will not work.
For diagnostics, you need to gain access to the compressor contacts (by removing the start relay) and ring them with a multimeter. Normal resistance values depend on the power of the motor, but usually are:
- ⚙️ Between the working and common windings: 10–30 Ohms.
- ⚙️ Between the starting and common windings: 20–60 Ohms.
- ⚙️ Between working and starting: the sum of the two previous values.
If the multimeter shows one (infinity), it means winding break. If it shows zero, an interturn short circuit has occurred. It is also critically important to check the breakdown on the housing: one probe is placed on any contact, the second on the copper tube or motor housing. The device should show infinity. If there is at least some resistance, the compressor is “broken” and requires replacement.
⚠️ Attention: If the compressor hums but does not start for more than 5-10 seconds, immediately unplug the refrigerator from the outlet! Operating in this mode quickly overheats the windings and can lead to a fire or permanent failure of the motor.
Sometimes the cause is a mechanical jam of the piston group. This happens when the system is left idle for a long time or moisture gets into the system. In this case, the engine tries to start, hums, twitches, but cannot turn the shaft. Attempts to “unwedge” the compressor by applying increased voltage are dangerous and rarely give long-term results.
The influence of the control board and electronics module
In modern refrigerators with a system Full No Frost and displays, the electronic control module is responsible for turning on the compressor. The board receives signals from sensors and, according to the algorithm, supplies voltage to the starting relay or directly to the inverter compressor. If a triac, relay or tracks on the board burn out, the start command will not be executed.
Symptoms of a board malfunction:
- Errors or chaotic symbols light up on the display.
- The refrigerator makes beeps.
- The compressor does not respond even when the thermostat contacts are forcibly closed.
Repairing the control board requires soldering skills and knowledge of circuit design. You can often visually see swollen capacitors or blackened elements. However, in inverter models (Bosch, Siemens), diagnostics are more difficult, since the module controls the shaft speed. Self-repair without an oscilloscope and knowledge is almost impossible.
Below is a table with approximate symptoms and probable causes for different types of control:
| Symptom | Mechanical control | Electronic control |
|---|---|---|
| Silent, no light | Problem with socket, cord, thermal protection | Board power supply, surge protector |
| Buzzes, but does not start | Starting relay, jammed compressor | Starting relay, inverter fault |
| Clicks and turns off | Faulty starting relay | Sensor error, burnt triac |
| Works jerkily | Rarely, poor contact is possible | Program failure, module malfunction |
☑️ Diagnostics before calling a technician
Specifics of inverter compressors
Refrigerators with inverter compressordeserve special attention. They do not have a classic starting relay in the usual sense. Starting and power regulation are carried out by a special inverter unit, which converts alternating current into direct current and controls the engine speed. If such a refrigerator does not start, the reason most often lies in the inverter module itself or in the stator windings.
Diagnostics of inverters is more complicated. Often the error indicator on the control module lights up. For example, flashing a light bulb a certain number of times indicates a problem with the switching module or a break in the windings. Error codes may indicate a malfunction of the sensor or the motor itself. LG flashing the light a certain number of times indicates a problem with the switching module or a break in the windings. U Samsung Error codes may indicate a malfunction of the sensor or the motor itself.
The peculiarity of inverter systems is that they are very sensitive to voltage surges. Even a short-term surge in the network can damage the control electronics, while the compressor itself remains intact. Therefore, owners of such models it is strongly recommended use high-quality surge protectors or voltage stabilizers.
If you hear a quiet hum or squeak from the bottom of the refrigerator with an inverter, but there is no start, most likely the control unit is trying to start the motor, but receives a feedback error. In this case, independent repair is only possible by replacing the entire module, since component repair requires special equipment.
Why are inverters quieter?
Inverter compressors do not turn off completely, but only reduce speed to maintain the temperature. This eliminates noisy start and stop cycles, making the refrigerator operate almost silently.
Frequently asked questions and answers (FAQ)
Can a compressor burn out due to long periods of inactivity?
Yes, it is possible. During long periods of inactivity (more than 6 months), the oil in the compressor drains into the system, and the remaining oil thickens. When turned on, the engine may run “dry” or be unable to turn the thickened piston, which will lead to overheating and jamming. It is recommended that after a long period of inactivity, let the refrigerator remain turned on in a warm room for several hours before loading food.
Why does the compressor start for a couple of seconds and immediately turn off?
This is a classic sign of a faulty start relay or thermal protection. The motor tries to start, the current increases sharply, the thermal protection is triggered and opens the circuit. This is also how a compressor with an interturn short circuit or a jammed mechanism behaves.
Is it dangerous to change a compressor yourself?
Replacing a compressor requires not only technical skills, but also special equipment: a vacuum pump, a pressure gauge station and a supply of freon. You cannot simply “re-solder” the tubes - the system must be evacuated and refilled with refrigerant strictly by weight. Without experience, there is a high risk of damaging a new compressor or creating a fire-hazardous mixture.
What to do if the refrigerator stops freezing after defrosting?
If the compressor does not start after defrosting, moisture may have gotten into the electrical contacts or into the start relay. Allow the equipment to dry completely for 24 hours in a dry room. If the problem persists, the thermostat or defrost sensor may have failed.