Sudden stop of the compressor - a situation familiar to many owners of household appliances. The refrigerator stops humming, the light inside is on, but the temperature gradually rises, threatening the safety of the food. Often the cause of a breakdown is not the motor itself, but starting relay a small but critical element of the electrical circuit, which is responsible for starting the engine.
Before calling a technician or buying a new unit, it makes sense to conduct independent diagnostics. This device is subject to natural wear and tear and power surges, so its failure is one of the most common causes of breakdown. In this article, we will look at how check the refrigerator relay available methods to understand whether it is possible to replace the part or whether the problem is deeper.
Timely detection of a malfunction will avoid more serious consequences, such as burning out the compressor windings. If you notice that the motor is trying to start, makes a click and immediately goes silent, or does not respond at all when plugged into the network, the first thing you should pay attention to is this unit.
Symptoms of a faulty starting relay
You can understand that the problem lies in the starting device by the characteristic signs. Users often confuse a relay failure with a malfunction of the thermostat or the compressor itself. However, starting relay has specific symptoms, ignoring which can lead to complete failure of the refrigerator.
The main symptom is a characteristic click, followed by silence or a hum, which ends abruptly. This means that the motor is receiving power, but cannot start. It is also worth paying attention to the appearance of the part: if traces of burning, melting are visible on the body, or the smell of burnt plastic is felt, diagnostics are practically not required - the element is burned out.
Sometimes the refrigerator works, but the compressor gets very hot, and the on/off cycles become chaotic. This may indicate that the contacts inside the relay are stuck, causing the motor to operate incorrectly. In such cases, checking start relay becomes a mandatory procedure.
- 🔊 The compressor clicks, but does not start, or starts for a split second.
- 🔥 The relay body has signs of overheating, blackening or deformation.
- ❄️ The refrigerator does not cool, although the indicators are on and there is light inside.
- ⚡ The circuit breaker in the electrical panel trips when you try to turn it on.
⚠️ Attention: If after clicking you feel a strong burning smell, immediately unplug the refrigerator. Operation of such a device can lead to a short circuit and fire of the wiring.
Design and principle of operation of the relay
For high-quality diagnostics, it is necessary to understand how this element works. The start relay is an electromagnetic switch that supplies current to the compressor start winding only when it starts. As soon as the motor rotor reaches the required speed, the relay opens the starting winding circuit, and the motor continues to operate on the main one.
In modern refrigerators, two types of devices are most often found: posistor and induction. PTC models operate on the basis of a thermoelement, which is heated by current and changes its resistance, opening the circuit. Induction (electromagnetic) uses the magnetic field of the coil to move the core and switch contacts.
It is important to note that the relay is also often built inside thermal protection relay. It opens the compressor power circuit if the current exceeds the permissible limits or if the motor housing overheats. Therefore, when checking, we often deal with a composite unit, where we need to ring both the starting and protective mechanisms.
What is the difference between a posistor and an electromagnetic relay?
A posistor is a ceramic element that, when heated by current, loses conductivity, actually breaking the circuit starting winding. It has no moving mechanical parts, so it is considered more reliable, but is sensitive to shock. An electromagnetic relay uses a moving core and coil and is noisier when operating (a clicking sound is heard) but is less susceptible to vibration.
Understanding the type of relay you have will help you choose the right testing strategy. If a posistor can be checked visually for cracks and ringed with a resistance tester, then in an electromagnetic device the mobility of the core and the condition of the contacts play a key role.
Removing the relay for testing
Before starting the test, the device must be removed from the refrigerator. This procedure does not require complex tools, but requires compliance with safety precautions. Any work on electrical components should only be carried out with the device completely disconnected from the mains.
First, find the compressor. It is usually located at the bottom rear of the refrigerator. Remove the protective plastic cover, if present, and disconnect the wires going to the relay. The relay itself is usually placed on three pins of the compressor and secured with a bracket or simply sits tightly on the terminals.
Carefully remove the part. Pay attention to the orientation: the case often has a marking UP or an arrow indicating the top position. This is important because some relays only work in a certain spatial position. After removal, inspect the contacts for oxidation.
- 🔌 Unplug the refrigerator from the outlet and wait 5-10 minutes.
- 🔧 Remove the back panel at the bottom of the unit to access the compressor.
- 📸 Take a photo of connecting the wires so as not to confuse them when assembly.
- 🧤 Carefully remove the relay from the compressor pins without using excessive force.
☑️ Safe removal of the relay
⚠️ Attention: Do not try to remove the relay by force, pulling the wires. This can lead to a break in the internal wiring of the compressor, the repair of which will cost much more than replacing the relay.
Diagnostics with a multimeter: step-by-step instructions
The most accurate way to check the functionality of the element is to use a multimeter in resistance measurement mode (Ohm). This method allows you to determine the integrity of the windings and the absence of a short circuit. If you do not have a multimeter, you can purchase it at any hardware store, as this is a basic tool for a home craftsman.
First, put the device in the continuity or resistance measurement mode. If you are testing a posistor relay, measure the resistance between the contacts. A working posistor at room temperature should show a resistance in the range from 10 to 60 Ohms (the exact value depends on the model). If the device shows infinity or zero, the part is faulty.
When checking an electromagnetic relay, it is necessary to ring the coil. Resistance should be low, but not zero. It is also important to check the contacts of the thermal relay: in a cold state they should be closed (resistance close to zero). If the circuit is open, the thermal protection has burned out.
Pay special attention to checking for short circuits. Place one multimeter probe on the contact and the other on the metal body of the relay. The device should not beep or show resistance. The presence of conductivity between the contacts and the body indicates an insulation breakdown.
If a visual inspection and testing do not reveal obvious defects, but the refrigerator does not work, you can try to gently shake the relay near your ear. If you hear the sound of broken glass inside or the knock of a torn element, the part definitely requires replacement, even if the multimeter shows normal.
Table of typical resistance values
When diagnosing, it is important to focus on standard indicators. Although the exact data depends on the manufacturer (Indesit, Atlant, Bosch), there are average values, deviation from which indicates a malfunction.
| Component type | Normal resistance | Fault symptom | Action |
|---|---|---|---|
| Posistor (starting) | 10 - 60 Ohm | Infinity or 0 Ohm | Relay replacement |
| Electromagnetic coil | 5 - 20 Ohm | Open circuit | Replacing the relay |
| Thermal relay (bimetal) | 0 Ohm (closed) | Infinity (open) | Relay replacement |
| Case insulation | Infinity | Any resistance value | Urgent replacement |
Using this data, you can accurately determine the condition of your part. Remember that even a small deviation in the resistance of the posistor can lead to the fact that it will not open the circuit in time, which will cause overheating of the compressor starting winding.
Replacement and testing after repair
If diagnostics showed that the relay is faulty, it must be replaced. You need to buy a part with exactly the same markings. There are no universal solutions here, since the mounting locations and electrical characteristics differ for different compressor models.
Install the new relay on the compressor pins, observing the orientation (top/bottom). Connect the wires according to the photo you took earlier. Make sure all connections are tight and not loose. After this, you can put on the protective cover and turn on the refrigerator.
The first start may take several minutes, since the refrigerator needs time to set the temperature and stabilize the pressure in the system. Listen carefully to the operation of the compressor: it should start smoothly, without buzzing or clicking, and work evenly.
- 🛒 Buy a relay with exactly the same markings as the old one.
- 🔌 Reinstall the part, observing polarity and orientation.
- ⏱ Turn on the refrigerator and wait 15-20 minutes for the first cycle.
- 🌡 Check whether the cold has begun to accumulate in the chambers.
⚠️ Attention: If after replacing the relay the compressor hums again, but does not start, or immediately knocks out the plugs, the problem may be in the compressor (interturn closure or wedge). Further attempts to turn on may permanently damage the motor.
Successfully replacing the relay often brings the refrigerator back to life, extending its service life by several years. The main thing is to correctly diagnose and use high-quality components.
Frequently asked questions (FAQ)
Is it possible to temporarily start a refrigerator without a relay?
Theoretically, you can start the motor by applying voltage directly to the starting winding, but this is strictly not recommended. Without a relay, the compressor will not be able to start correctly and will quickly burn out due to overheating of the starting winding. This is an emergency mode, and not a solution to the problem.
Why does the relay burn out?
The main reasons: power surges in the network, contact wear from frequent switching on/off, overheating of the compressor due to a dirty capacitor or a malfunction of the thermostat. Also, the relay may fail due to manufacturing defects or moisture.
How much does it cost to replace the relay?
The cost of the part itself usually ranges from 500 to 2000 rubles, depending on the model of the refrigerator. If you do the replacement yourself, this is your only expense. The services of a master can increase the amount by 2-3 times.
Is it possible to repair an old relay?
At home, repairing a relay is impossible and impractical. This is a sealed or complex assembly that cannot be disassembled without damage. Attempts to clean the contacts or glue the body will only give a temporary effect and can be dangerous.