Situation, when the refrigerator turns on and immediately turns off, is one of the most common and troubling problems faced by owners of household appliances. You hear a characteristic click, the compressor begins to hum, but literally after 5–15 seconds another click is heard and the unit goes silent. The cycle may repeat indefinitely or stop indefinitely until you try to start the device again. This behavior indicates that the protection system is forcibly activated, preventing more serious damage, such as burning out the motor windings.
There can be many reasons why refrigerator behaves this way: from a banal power surge in the network to the failure of an expensive motor-compressor. Most often, the problem lies in the start relay, which cannot start the engine correctly, or in the thermostat, which erroneously sends a shutdown signal. Understanding the physics of the process will help you save time and money, since in many cases repairs can be done yourself without calling a technician.
In this article we will analyze in detail all the possible causes of the malfunction, methods for diagnosing them and ways to eliminate them. We will consider both simple cases that require minimal intervention, and complex technical breakdowns. It is important to carefully monitor the symptoms: whether the unit makes extraneous sounds, whether the housing heats up, and how often the on-off cycle is repeated.
The principle of operation of the compressor protective mechanisms
To understand why the refrigerator clicks and does not start, you need to understand the basic principle of operation of the start-protection relay. This small component is responsible for providing a starting pulse to the motor winding and then maintaining its operation. If the starting current is too high or the engine does not reach the required speed, the thermal relay opens the circuit, making that same click.
The process of starting the motor-compressor takes a split second, but it is at this moment that the load on the network and internal components is maximum. If starting relay faulty or the contacts are oxidized, the engine does not receive the desired boost. As a result, thermal protection is triggered, which heats up from the passing current and physically opens the contacts to prevent overheating and fire.
There are several types of relays: posistor and induction. PTC models work by changing resistance when heated, while induction models use an electromagnetic coil. Failure of any element of this chain leads to the fact that the refrigerator turns off after a few seconds after the start. This is a standard reaction of the safety system, which is often confused with a breakdown of the compressor itself.
It is important to note that frequent attempts to start in this mode are detrimental to the motor windings. Each start-stop cycle causes high heat, which can lead to turn-to-turn shorting. Therefore, if you notice that the unit is operating intermittently, you must immediately stop using it and carry out diagnostics.
⚠️ Attention: If, after several unsuccessful startup attempts, you smell a burning or scorched plastic smell, immediately unplug the refrigerator. Continued operation may lead to a fire in the wiring or complete failure of the compressor.
Faults in the starting and thermal relays
The most likely reason that the refrigerator turns on and immediately turns offlies in the starting relay. This component is subject to natural wear and tear, especially in older models of equipment. The plastic housing of the relay may melt, and the internal contacts may turn black from sparking, which prevents the normal transmission of electric current.
Diagnostics of the relay begins with a visual inspection. Remove the back cover of the refrigerator and locate the black cylindrical or rectangular block attached to the compressor. Carefully disconnect it and shake it: if a ringing or knocking sound is heard inside, it means that the posistor has crumbled and the part requires replacement. Also pay attention to the condition of the contacts - they must be clean and free of carbon deposits.
- 🔌 Oxidation of contacts: Over time, an oxide film forms on the copper contacts, which increases resistance and prevents the engine from starting. Cleaning the contacts with fine sandpaper sometimes solves the problem.
- 🔥 Overheating of the posistor: If the posistor has lost its properties, it does not switch the windings at the right time, and the compressor hums, but does not start, after which the protection is triggered.
- 🧊 Moisture inside the relay: In conditions of high humidity, moisture may condense inside the relay housing, causing a short circuit or corrosion of the contacts.
Replacing a relay is one of the simplest procedures in repairing refrigerators. You will need a new part that exactly matches your compressormodel. Part numbers are usually located on the old relay housing or in the technical documentation. Installation takes no more than 15 minutes and does not require a special tool other than a screwdriver.
How to test a relay with a multimeter?
To check the relay, use a multimeter in continuity mode. The posistor should ring (have resistance) when cold. The thermal relay should also ring if it is not heated. If the multimeter shows infinite resistance or a short circuit, the part is faulty.
Problems with the thermostat and temperature sensors
The thermostat (or thermostat) is the “brain” that decides when to turn the refrigerator on and off. If this device is malfunctioning, it may send incorrect signals. For example, the thermostat may “think” that the chamber is already cold enough, and immediately after starting the compressor, give a command to turn off. As a result, the illusion is created that the refrigerator turns off by itself.
In modern models with a system No Frost and electronic control, instead of a mechanical thermostat, air temperature sensors are used. If such a sensor is dirty, misaligned, or damaged, it may send erroneous data to the control module. The electronics, receiving a signal that the target temperature has been reached, turns off the compressor, even if in reality it is warm in the chamber.
Diagnostics of the thermostat is often carried out by the method of exclusion. In mechanical models, you can temporarily close the thermostat contacts (bypassing it). If the refrigerator starts working continuously when the contacts are closed, then the problem is in the regulator. However, this method requires caution and electrical skills.
Malfunctions of the motor-compressor
The most unpleasant scenario is a breakdown of the very heart of the refrigerator, the motor-compressor. If the refrigerator hums and turns offbut the relay and thermostat are working properly, there is a high probability of problems with the engine. Most often, an interturn short circuit of the windings or jamming of the piston group occurs.
When there is an interturn short circuit, the resistance of the windings drops, the current increases sharply, and the thermal relay instantly trips, turning off the power. You can check this by measuring the resistance of the windings with a multimeter. Normal values are usually in the range of 20 to 40 ohms for the start and run windings. If the device shows zero or one (infinity), the compressor is faulty.
A compressor stall occurs when the mechanical parts of the engine seize due to lack of oil or wear. In this case, the shaft cannot rotate, the current rises to a maximum, and the protection turns off the device. Sometimes the compressor can be “unwedged” by applying increased voltage, but this is a temporary measure, and soon a complete replacement of the unit will be required.
Problems with the wiring and control module
In modern refrigerators, an electronic control module is responsible for all processes. If the control board is faulty, it may not supply the correct voltage to the start relay or misinterpret sensor signals. In such cases the refrigerator turns on and off in a chaotic manner, regardless of the temperature in the chamber.
It is also worth paying attention to the integrity of the wiring. Broken wires, especially at door bends or near the compressor, can cause short circuits or loss of contact. Oxidation of connection connectors is also a common cause of unstable operation of equipment.
Diagnosing the control module often requires special equipment and knowledge in the field of electronics. If you do not have experience in repairing electronic circuit boards, it is better to contact specialists. An independent attempt at repair can lead to aggravation of the situation and failure of other expensive components.
| Symptom | Probable cause | Difficulty of repair | Required tools |
|---|---|---|---|
| Click after 3-5 seconds of humming | Faulty start relay | Low | Screwdriver, multimeter |
| Shutdown without humming | Thermostat malfunction | Medium | Screwdriver, tester |
| Strong hum and heating of the housing | Compressor jamming | High | Set of keys, burner |
| Chaotic switching on | Control module failure | High | Soldering iron, programmer |
External factors and the quality of the power supply
Do not discount external factors. If the voltage in your home is unstable, the refrigerator may turn off due to the operation of the built-in surge protection. Low voltage does not allow the compressor to develop the necessary power to start, and it stalls.
A faulty socket or extension cord may also be the cause. Poor contact at the junction of the plug and socket causes heating and voltage drop, which is perceived by equipment as an emergency situation. Always plug powerful electrical appliances directly into a working outlet.
To protect equipment, it is recommended to use a voltage stabilizer or surge protector with a surge protection function. This is especially true for country houses and old apartment buildings, where the quality of power supply leaves much to be desired.
☑️ Diagnostics before calling a technician
⚠️ Attention: Using cheap Chinese extension cords to connect the refrigerator is strictly not recommended. They often cannot withstand the starting currents of the compressor, which can lead to melted contacts and a fire.
Methods for self-diagnosis and repair
If you decide to try to fix the problem yourself, start with safe methods. First of all, defrost the refrigerator (if it is not No Frost) and let it stand unplugged for several hours. Sometimes this helps relieve the heat load and start the stuck compressor.
Then check the start relay. Remove it, inspect it for burning and test it with a multimeter. If the relay is OK, check the thermostat. In mechanical models, you can carefully close its contacts with wire (only for a short time to check!). If the compressor starts working, change the thermostat.
If all external elements are in good condition, but the compressor still does not start or immediately stalls, the problem is most likely inside the engine. Here you cannot do without the help of a professional and special tools (press, vacuum pump, burner). Replacing a compressor is a complex process that requires recharging the system with refrigerant.
Prevention and operating rules
To avoid repeating the situation when The refrigerator turns on and then turns off immediately, it is important to follow the operating rules. Do not place hot foods in the chamber, as this creates excess load on the compressor, forcing it to work at its limit.
Regularly clean the condenser (the grill at the back of the refrigerator) of dust. A dusty condenser does not transfer heat well, the compressor overheats and the thermal protection is triggered. It is enough to vacuum the back panel once every six months to ensure normal heat exchange.
Keep an eye on the door seals. If they are worn out or dirty, warm air enters the chamber and the refrigerator is forced to work almost without interruption. This reduces the life of the compressor and increases the risk of breakdown. Wipe the seals with a damp cloth and check their fit.
Frequently asked questions (FAQ)
Why does the refrigerator click but does not start?
The click is usually made by the start relay or thermal protection. If the click is followed by a hum and then clicks again a few seconds later, the compressor is trying to start, but the protection is shutting it down due to overload. Most often, a burnt-out start relay or a jammed compressor is to blame.
Is it possible to temporarily use a refrigerator with a faulty relay?
It is strictly not recommended. Constant attempts to start with a faulty relay lead to overheating of the compressor windings. In the best case, the motor itself will burn out, in the worst, a fire may occur. Repairing the relay is inexpensive and can be done quickly.
How long should the refrigerator work before turning off normally?
In normal mode, the refrigerator operates cyclically: it works for 15–30 minutes, rests for 30–60 minutes. The exact ratio depends on the model, room temperature and chamber load. If the cycle lasts several seconds, this is an emergency mode.
Does the number of products affect the frequency of switching on?
Yes, it does. An empty refrigerator cools down faster, but it also heats up faster when the door is opened. A full refrigerator (especially with food with a high water content) will hold the cold better, but will take longer to initially cool down. However, sudden changes in cycles more often indicate a breakdown than a load.
What to do if after defrosting the refrigerator still turns off?
If defrosting for 12-24 hours did not help, the problem is of a technical nature. It is necessary to check the electrical circuit: socket, cord, relay, thermostat and compressor. Continuing operation in this mode is dangerous.