The situation when your favorite refrigerator stops buzzing and cooling food, always takes you by surprise. Silence in the kitchen instead of the usual hum of the engine is the first alarm signal that cannot be ignored. If you notice that the compressor does not startand it is getting warm inside the chamber, it means that there has been a failure in the system that requires immediate attention.
The reasons for this behavior of the unit can be very different: from a banal power surge in the network to a complex mechanical breakdown of the engine. In some cases, the equipment simply “went into defense” and needs time to cool down, but often a full-fledged diagnostics node is required. Understanding the nature of the malfunction will help you decide whether you should call a technician or you can fix the problem yourself.
In this article we will analyze in detail the main factors affecting engine starting and help you determine the source of the problem. You will learn how to check start relay, assess the condition of the thermostat and understand when you can’t do without calling a specialist.
Primary diagnostics: eliminating external factors
Before disassembling the case or calling the service center, you need to make sure that the refrigerator receives electricity. Sometimes the problem lies not in the unit itself, but in the outlet or extension cord. Check whether backlight bulb the inside of the chamber lights up when the door is opened. If there is light, but the motor is silent, it means that voltage is being supplied, and the reason lies deeper.
Pay attention to the condition of the power cord and plug. There should be no traces of melting, cracks or creases on them. If you are using an extension cord or surge protector, try connecting the refrigerator directly to the wall. Often, old or cheap extension cords cannot withstand the starting current of the motor, which is why contacts burnand the equipment stops working.
⚠️ Attention: If you smell a burning smell or see sparks in the socket area, immediately stop trying to turn it on. Use only working sockets with grounding that correspond to the power of the device.
It is also worth checking whether the door fits tightly to the body. If the seal is worn out or a piece of food is stuck on the edge, the temperature sensor may “think” that the chamber is cold and not give the command to start. Make sure that the gap between the camera and seal is minimal around the entire perimeter.
Malfunctions of the thermostat and temperature sensors
One of the most common reasons why the compressor does not turn on is the failure of the thermostat. It is this element that is responsible for controlling the temperature inside the chambers. When the air warms up above the set norm, the thermostat closes the electrical circuit, starting the motor. If the contact does not close, compressor simply does not receive a signal to operate.
In modern models with the No Frost system, instead of a mechanical thermostat, electronic sensors (thermistors) can be used. They transmit data to the control module. If the sensor “lies” and shows that the temperature is normal, although the chamber is warm, the refrigerator will not start. Checking such elements requires a multimeter to measure resistance.
Symptoms of a malfunctioning thermostat often appear as follows:
- ❄️ The compressor is silent, although the food has begun to defrost.
- 🔊 Heard there is a click, but the engine does not start.
- 🌡️ The temperature inside the chamber does not correspond to that set on the regulator.
For mechanical thermostats, there is a simple test method: short-circuit the wires going to the sensor, bypassing the regulator itself. If after this manipulation the refrigerator starts working, it means thermostat it is faulty and requires replacement. However, remember that working with electricity requires disconnecting the device from the network.
Problems with the start protection relay and capacitor
The start relay is a small but critical element that is located next to the compressor. Its task is to apply a powerful impulse to the motor winding to start, and then turn off the starting winding. If the relay burns out or the contacts are stuck, the engine will only hum, trying to start, but the shaft will not rotate. After a few seconds, it will work thermal protectionand the motor will shut down.
Some models also have a starting capacitor, which helps smooth out voltage surges at startup. Its breakdown or loss of capacity also makes it impossible to start. A visually faulty capacitor may be swollen, but often the defect is visible only when measuring the capacitance device.
Signs of a faulty starting group:
- 🔌 A characteristic click is heard, then a hum and a second click (the cycle repeats).
- 🔥 The relay or compressor housing gets very hot in the lower part.
- ⚡ The machine in the electrical panel knocks out when you try to turn it on.
Replacing the relay is one of the most accessible repair procedures. You need to remove the casing at the back of the refrigerator, disconnect the old unit and install the new one, strictly observing the orientation (top-bottom). It is important to choose a relay with exactly the same characteristics as the original, otherwise motor it may burn out.
⚠️ Attention: The starting relay is a consumable item. If you replaced it with a new one, and a month later the situation repeated itself, the problem may not be in the relay, but in the compressor itself or the wiring.
Starting the engine: checking the windings and interturn short circuit
If everything is in order with the electrics and the relay, it is worth checking the “heart” of the refrigerator itself - the compressor. The engine has two main windings: working and starting. To diagnose, you need to “ring” them with a multimeter. The normal resistance of the working winding is usually 10-20 Ohms, and the starting winding is 30-40 Ohms (values can vary e depending on the model).
If the device shows infinity (open circuit) or zero (short circuit), then the windings burned out. Another dangerous malfunction is turn-to-turn short circuit. In this case, the resistance of the windings may be normal, but the current consumption at startup will exceed the rated value, which leads to instantaneous operation of the protection. This can only be detected using a motor tester or pliers.
Below is a table of typical resistance values for different types of compressors:
| Compressor type | Starting resistance windings (Ohm) | Working winding resistance (Ohm) | Case resistance |
|---|---|---|---|
| Single-phase (standard) | 30 - 45 | 10 - 20 | Infinity |
| Inverter | Checked according to the circuit | Checked according to the circuit | Infinity |
| Linear | N/A (works from inverter) | N/A (powered by inverter) | Infinity |
| With interturn short circuit | Below normal | Below normal | Infinity |
If resistance is detected between the windings and the body (short circuit to the body), operating such a refrigerator is deadly. Such a unit requires professional repair or replacement motor-compressor.
What is an inverter compressor and how to check it?
Inverter motors do not have a classic starting relay. They are controlled by a complex electronic unit. It is impossible to check them by “continuity” as usual - you need to send a test signal through a special adapter or change the control unit.
Freon leakage and protection against “dry running”
Modern refrigerators are equipped with safety systems that block the start of the compressor in the absence of refrigerant. If an accident occurs in the circuit, the pressure drops and the motor may either not start at all or run in very short cycles. This is done to prevent overheating, since freon also cools the motor windings. freon leak, the pressure drops, and the engine may either not start at all or run in very short cycles. This is done to prevent overheating, since freon also cools the motor windings.
It is difficult to determine a leak visually, but there are indirect signs. Frost may not form on the evaporator (inside the freezer), or it may only form in one corner. The condenser tubes (grill at the back) will be cold or room temperature when they should be hot during normal operation. A hissing sound may also appear from the place where the tube is damaged.
Attempts to start the compressor in the absence of freon can lead to it jamming. The oil circulating along with the gas does not enter the rubbing pairs, and dry friction occurs. Therefore, if you suspect a leak, it is better not to experiment with repeated switching on.
⚠️ Attention: Freon is a gas under pressure. Self-refueling requires evacuation of the system and special equipment. An attempt to refill “by eye” will ruin the compressor.
Compressor jamming and mechanical breakdowns
The most unpleasant scenario is mechanical jamming of the compressor. This occurs when the piston group wears out, a valve breaks, or internal parts fail. In this state, the motor shaft cannot turn, and the motor only hums while under load. The thermal relay quickly turns off the power to prevent a fire.
Sometimes the compressor jams due to oil solidifying in a cold room or after a long period of inactivity. In such cases (if there is no mechanical destruction), the so-called “wedging” method by applying increased voltage can help, but this is a risky procedure, accessible only to experienced craftsmen. For an ordinary user, this is a signal to replace the unit.
Signs of jamming:
- 🔨 Strong vibration of the housing when trying to start.
- 🔥 Sudden heating of the compressor housing in 10-15 seconds.
- 🔌 Instant protection even with a new relay.
If the compressor is really jammed, repairs are not economically feasible. The cost of a new motor and re-soldering of pipes is often 70-80% of the price of a new refrigerator. In such cases, it is more advisable to consider purchasing new equipment.
Failures in the electronic control module
In electronically controlled refrigerators (where the temperature is set in degrees on the display), control moduleis responsible for starting the compressor. This is the “brain” of the device, which receives signals from sensors and commands the actuator. If the triac on the board that controls the motor burns out, or there is a failure in the firmware, the start command will not be received.
Often the module fails due to power surges or moisture. Visually, blackening, swollen capacitors, or traces of corrosion may be visible on the board. Diagnostics of the module requires special knowledge in electronics. Sometimes a full reset helps (disconnecting from the network for 15-20 minutes), but if the problem is in the hardware, you will need to replace the board or resolder the elements.
In modern models LG, Samsung, Bosch and other brands, control modules are very sensitive to the quality of the power supply. Using a high-quality voltage stabilizer can extend the life of electronics.
☑️ Checklist before calling a technician
Frequently asked questions (FAQ)
Why a refrigerator clicks, but does not start?
The click is the sound of the starting relay or heat sink. If there is no buzz after the click, there may be no voltage coming to the motor. If there is a hum, but there is no start, the start relay is most likely faulty, the compressor is jammed, or the winding is burned out.
Is it possible to start a refrigerator without a thermostat?
Temporarily - yes, if you short-circuit the thermostat wires directly. This will allow you to check the operation of the compressor. However, you cannot operate the refrigerator like this all the time: it will work continuously, which will lead to freezing of the evaporator and spoilage of food.
How long should the compressor rest after defrosting?
After complete defrosting, the refrigerator needs to be turned off for at least 2-4 hours (preferably a day) so that the oil flows into the compressor crankcase and the moisture evaporates. Switching on ahead of time can lead to water hammer and breakdown.
It hums, but does not start - is this dangerous?
Yes, it is dangerous. A humming sound means current is flowing, but there is no rotation. The windings heat up quickly, the insulation melts, which can lead to a short circuit and fire. If there is a long hum without starting, immediately disconnect the device from the network.
Why does not the new refrigerator start after delivery?
If the refrigerator was transported lying down, the oil needs time (up to 24 hours) to return to the compressor. Also check that all shipping bolts and wedges have been removed and that the thermostat is set to the correct temperature.