The sudden stop of the refrigerator often causes panic, but in many cases the cause of the breakdown is failure start relay. This small but critical element is responsible for starting the compressor engine and protecting it from overloads. If you hear clicks, a hum that suddenly stops, or the compressor does not start at all, there is a high probability that the problem lies in this particular unit.
Independently replacing the relay is a task that is accessible to a person with basic skills in handling tools, but requires strict adherence to electrical safety rules. Incorrect connection or ignoring diagnostic nuances can lead to burnout of the motor windings, which will turn a simple repair into an expensive replacement of the entire unit. In this article we will analyze in detail the structure of the mechanism, the algorithm of actions and connection diagrams.
Before starting disassembly, you need to understand that different models of refrigerators can be equipped with different types of relays. There induction, thermal there are also combined devices, each of which has its own design features. Incorrect installation of an incompatible component will not only not solve the problem, but can also create a dangerous situation in the electrical network of your home.
Design and principle of operation of the starting relay
The starting relay is an electromechanical a switch that closes the circuit of the engine starting winding at the moment of start. As soon as the compressor rotor reaches the required speed, the relay opens the circuit, putting the engine into operating mode. Modern models often use devices with a posistor, which operate based on changes in resistance when heated, which eliminates the need for movable mechanical contacts.
Inside the body of a classic induction relay there is a coil through which the current of the working winding passes, and a movable core with contacts. When voltage is applied, the current increases sharply, the magnetic field draws in the core and closes the contacts of the starting winding. When the motor accelerates, the current drops, the spring returns the core, and the circuit opens. Violation of this process, for example, sticking of contacts, leads to the fact that the compressor hums, but does not start.
The thermal relay, which is often paired with the starting one or combined with it, performs a protective function. It contains a bimetallic strip that bends when the permissible current or temperature is exceeded, breaking the power circuit. This prevents overheating and melting of the winding insulation. Important to understandthat if the thermal relay constantly trips, this may indicate an interturn short circuit in the motor or problems with the compressor cooling system.
⚠️ Attention: In some models the relay refrigerators Indesit and Ariston there is a specific design with an additional capacitor. An attempt to replace such a relay with an analogue without a capacitor or with other parameters will lead to instant failure of the starting winding.
The durability of the relay directly depends on the stability of the voltage in the network and the quality of the contacts. Frequent voltage surges can cause burning of contacts or degradation of the posistor. That is why, to extend the life of expensive equipment, it is recommended to use voltage stabilizers, especially in areas with unstable power supply.
Fault diagnosis before replacement
Before buying a new part and disassembling the unit, you need to make sure that the problem lies in the relay, and not in the compressor itself or the wiring. Primary diagnosis is carried out visually and auditorily. If, when you plug in the refrigerator, you hear a quiet hum lasting 5-10 seconds, followed by a click and silence, this is a classic symptom of a faulty starter or a jammed compressor.
For a more accurate check of the relay, it must be removed from the refrigerator. Disconnect the device from the network, remove the rear protective cover at the bottom and disconnect the block with wires. Carefully remove the relay from the compressor contacts. An external inspection may reveal traces of soot, melted plastic or a characteristic burning smell, which clearly indicates the need for replacement.
Checking the integrity of internal elements is carried out using a multimeter. Switch the device to resistance measurement mode. For induction relays, the coil resistance should be close to zero, and the contacts in the inverted position (as during operation) should close. In a cold state, posistor relays should have a resistance within tens of Ohms, and when heated, go to infinity.
- 🔍 Visual inspection: look for blackening, cracks on the body and melted contacts, which indicate overheating.
- 🔊 Audio test: shake the relay near your ear - if you hear a knocking sound internal parts, which means the mechanical part is destroyed.
- ⚡ Disconnection test: use a multimeter to check the conductivity of the circuit in different positions of the device.
- 🌡️ Temperature test: heat the posistor with a hairdryer and check whether its resistance increases to infinity.
If the diagnostics confirmed a relay malfunction, but you are not confident in your abilities, it is better to turn to professionals. However, if you decide to continue the repair yourself, strictly follow the removal and installation instructions so as not to damage the fragile elements of the system.
Preparation for work and safety precautions
Working with electrical appliances and refrigerant requires increased caution. The first and most important rule is to completely disconnect the refrigerator from the power supply. It is not enough to simply turn off the button; you must unplug the plug from the socket. This will eliminate the risk of electric shock if you accidentally touch exposed contacts or live housing parts.
To carry out the work, you will need a minimum set of tools: pliers, a screwdriver (Phillips and flat-head), a multimeter and, possibly, electrical tape or heat shrink to insulate the connections. It is also recommended to prepare gloves, since the internal surfaces of the refrigeration unit may be contaminated with oil or technical liquids.
Particular attention should be paid to the condition of the compressor tubes. They are made of thin copper and are easily deformed. If you move carelessly, you can damage the sealed connections, which will lead to freon leakage. In this case, the repair will go beyond simply replacing the relay and will require calling a technician with equipment for vacuuming and refilling the system.
☑️ Preparation for replacing the relay
Before starting disassembly, it is strongly recommended to photograph the location of the wires and the connection diagram of the old relay. Even if you plan to install an original spare part, the color marking of the wires may differ from one manufacturer to another. The photo will help to avoid errors during assembly and ensure correct connection of the contacts.
Removing the old relay: step-by-step instructions
The process of removing the relay begins with access to the compressor, which is usually located in the lower rear part of the refrigerator. Remove the cardboard or metal protective panel by unscrewing the mounting bolts or removing the latches. You will see a view of the black compressor tank with the corresponding tubes and electrical box.
Carefully disconnect the electrical block with wires that goes to the relay. It can be fixed with a latch or simply sit tightly on the contacts. Do not use excessive force to avoid breaking the wires. If the block has become stuck over time, you can slightly rock it from side to side.
The relay itself is placed on three contacts of the compressor and can be additionally secured with a bracket or holder. Remove the retaining bracket, if present, and gently pull the relay down, wiggling it slightly. It is important not to pull the wires, but to grasp the device body directly. The old relay should easily come off the pins.
| Contact type | Designation on the diagram | Wire color (standard) | Function |
|---|---|---|---|
| Common (C) | Common | Black or White | Power supply for working and starting windings |
| Working (R) | Run | Brown or Red | Supporting engine operation |
| Starting (S) | Start | Blue or Green | Starting the engine rotor |
| Ground | Ground | Yellow-green | Case ground |
After removing the relay, inspect the contacts on the compressor itself. They must be clean, free of oxides and soot. If you notice traces of sparking or melting on the motor pins, they must be carefully cleaned with fine sandpaper or a file before installing a new element.
Connection diagram and installation of a new relay
Installation of a new relay is carried out in the reverse order of removal. However, it is critically important to correctly orient the device relative to the compressor contacts. The relay body usually has a marking UP or an arrow indicating the upward direction. Incorrect orientation will result in the mechanism not working or the contacts not closing.
Push the relay onto the compressor contacts until it stops. Make sure it fits snugly and doesn't wobble. If the design includes a retaining bracket or spring clip, be sure to install it in place. This will ensure reliable contact and vibration resistance.
Connect the wires to the relay terminals according to the photograph or color marking taken earlier. Typically, the wires are fixed into a terminal block, which is then placed on the relay contacts. Check that each wire fits into its socket until it clicks and does not dangle.
What to do if the new relay does not fit in the connector?
In some cases, manufacturers change the design of the connectors. If the purchased relay does not physically fit into the socket of your refrigerator, you can carefully transfer the contacts from the old socket to the new one, observing the polarity. However, this requires soldering skills and careful insulation of connections. It is better to look for an exact analogue by catalog number.
After assembling all electrical connections, check again that all elements are securely fastened. No wires should touch hot parts of the compressor or sharp edges of the metal housing. Secure the wires with plastic clamps, if necessary.
⚠️ Attention: When installing the relay, make sure that it is positioned strictly vertically, as installed by the manufacturer. A tilt or horizontal position can disrupt the operation of the mechanical armature or thermal protection, which will lead to rapid combustion of the new part.
Checking the functionality and starting the system
After installing the relay and connecting the wires, you can proceed to a test run. Do not replace the back cover yet to be able to observe the process and hear the operation of the unit. Plug in the refrigerator.
In the first seconds, you can hear a characteristic click of the relay, followed by the smooth hum of the operating compressor. If the engine starts and runs smoothly, without vibrations or extraneous sounds, then the replacement was successful. After some time (10-15 minutes), check whether the evaporator inside the chamber begins to cool.
If you again hear a humming sound that ends with a click, immediately unplug the refrigerator. This means the problem is not resolved. Perhaps the compressor itself is faulty (interturn short circuit or jamming) or a low-quality relay has been newly installed. Repeated starting attempts can finish off the engine.
- 🎧 Listen to the rhythm: A running compressor makes a monotonous sound without sudden changes.
- 🌡️ Control temperature: After 30 minutes of operation, check the temperature in the chamber - it should begin to decrease.
- 🔌 Checking heating: gently touch the relay body (be careful, it may get hot) - strong heating indicates poor contact.
After making sure that all systems are working normally, turn off the refrigerator, replace the protective back cover and securely fasten it with fasteners. Only after this can you move the refrigerator to the wall and connect it for continuous operation.
Common mistakes and recommendations from specialists
One of the most common mistakes is installing a relay without clarification reasons for the failure of the previous one. If the old relay burned out due to a power surge or problems with the compressor, then the new one will not last long. Always analyze the state of the electrical network and the engine itself.
Another mistake is using relays from other refrigerator models by eye. They may be similar in appearance, but differ in operating currents or connection type. Using an unsuitable relay can result in the starting winding being turned on for too long, which will cause it to overheat and breakdown.
Some craftsmen advise cleaning the contacts of the old relay with sandpaper and putting it back. This is a temporary measure that rarely produces long-term results. The contact metal has already burned out, and such a relay will soon fail again, perhaps with more dire consequences for the compressor.
Remember that the quality of repair work directly affects the service life of household appliances. Accuracy, using the right tools and following the sequence of actions are the key to success. If you are in doubt at any stage, it is better to stop and consult with a professional.
Questions and answers (FAQ)
Is it possible to start a refrigerator without a starting relay?
Theoretically, you can start the engine by manually closing the contacts of the starting winding, but this is strictly prohibited in domestic conditions. This requires precise knowledge of the opening moment and carries a high risk of electric shock or burning of the windings. Without a relay, the compressor will not be able to switch to operating mode and will quickly burn out.
Why did the new relay burn out a few minutes after installation?
This may indicate a malfunction of the compressor itself (for example, jamming of the piston group or an interturn short circuit), due to which the current in the windings exceeds the norm. Also, the cause may be incorrect installation of the relay (wrong side up) or a power surge in the network.
Where can I find the marking of a replacement relay?
The marking is usually applied to the side or top edge of the plastic relay case. This may be a manufacturer code (for example, PTC, R6, 117N) or a catalog number. Information can also be found in the technical documentation for the refrigerator or on the manufacturer’s website for the unit model.
What is the difference between a posistor and induction relay?
Induction relays use an electromagnetic coil and a movable core to close the contacts. PTC posistors use a ceramic element that changes its resistance when heated by current, breaking the circuit. They do not have moving mechanical parts and are considered more reliable, but are not interchangeable without changing the connection diagram.
How much does it cost to replace a relay in a service center?
The cost consists of the price of the part itself and the work of the technician. The part is usually inexpensive, but a specialist visit and diagnostics can cost significantly more. Self-replacement allows you to save on work, but requires tools and minimal skills.