When a household refrigerator stops cooling, and the compressor either hums but does not start, or makes a characteristic click and goes quiet, the first thing to check is the start-up relay. This device is a key element of the motor’s electrical circuit, responsible for supplying voltage to the starting winding at the moment of start. Understanding exactly where the relay is located is necessary for quick diagnosis and possible replacement of the part, since it is this component that often fails due to overloads or natural wear of the contacts.
The location of the starting relay directly depends on the design features of your unit, but in 95% of cases it is mounted directly on the compressor housing. You do not have to disassemble the entire refrigerator or remove the back wall if access to the technical area is not blocked structurally. Usually it is enough to move the unit away from the wall to gain access to the lower part where the motor is hidden.
In this article we will analyze in detail the algorithm for searching for relays on models from different manufacturers, consider the mounting features and types of protective covers. You will learn how to safely remove a part for visual inspection and what signs indicate its malfunction. Relay localization This is the first step to restoring the functionality of your kitchen appliances, which you can do yourself with a minimum set of tools and following safety precautions.
Structural location and access to the compressor
The start relay is always mounted on the output contacts of the compressor, which, in turn, is located at the bottom of the refrigerator. In classic models with an open compressor compartment, the motor is immediately visible as soon as you look behind the back wall of the refrigerator. However, in modern units, especially built-in ones or models with a solid rear panel, access may be limited by a decorative casing or metal cover covering a technical niche.
To gain access to the compressor area, you will most likely need to remove this protective cover. It can be snapped on or screwed on. After removing the cover, you will see a black cylindrical or spherical tank - this is the compressor. It is on its upper or side part (depending on the orientation of the rods) that there are three electrical contacts onto which the desired device is put on.
Sometimes access to the relay is complicated by the presence of an additional plastic box or tray for collecting condensate, which is located directly above the compressor. In such cases, it is necessary to carefully dismantle the tray, first draining any water from it if it has accumulated there. Compressor compartment Must be completely free of foreign objects so that you can freely manipulate the tool around the motor.
⚠️ Attention: Before removing any protective panels, make sure that that the refrigerator was disconnected from the power supply at least 15-20 minutes ago. The capacitors in the circuit can retain a charge, and the compressor itself can be very hot in the first minutes after operation.
In some refrigerator models, for example, certain series Indesit or Stinol, the compressor may be partially recessed into a niche, and access to the side contacts is difficult. In such a situation, you may need to carefully tilt the refrigerator (keeping an angle of no more than 40 degrees so that oil does not enter the cooling system circuit) or temporarily remove the motor mounting bolts to displace it, although the latter is required extremely rarely.
Visual identification of the start relay
Once you have gained access to the compressor, you need to correctly identify the start relay among other elements. It is a small plastic case, usually black, gray or white, which is literally “attached” to three pins protruding from the compressor housing. The shape of the relay can be rectangular, cubic or slightly elongated, which depends on the manufacturer and series of the refrigerator.
A wiring harness coming from the thermostat or electronic control module is always suitable for this case. The wires can enter directly into the relay body through a connector or be connected to terminals covered with a cover. If you see a device attached to the motor terminals and with wires suitable for it, you have found what you were looking for. Often next to the relay, on the same terminals or on the side, there may be a thermal protector (thermal protection relay), which is sometimes combined with the starting relay into a single unit.
It is worth noting that in inverter refrigerators the starting system is designed differently, and the classic starting relay may not be there; its functions are performed by an electronic control unit. However, in traditional linear models, the relay is a standard element. Plastic case the relay is often marked with a part number, which will help you find an exact replacement in case of breakdown.
Visually, the relay can be distinguished by its characteristic fastening: it is not screwed to the compressor, but is held by due to a tight fit on the contacts and, sometimes, fixed with a metal bracket or plastic frame. If you try to gently (without jerking) swing this element, it will move along with the compressor leads, while the motor itself will remain motionless.
Dismantling and removing the protective casing
Before you begin to remove the relay, you need to prepare the workplace and tools. You'll need a flat head screwdriver, possibly some pliers, and a container for any small parts you might need. It would also be a good idea to take a photo of connecting the wires before starting work, so as not to confuse the contacts during assembly, although it is physically difficult to confuse them due to the unique shape of the connectors.
The dismantling process begins with disconnecting the wire block. Depending on the model, the connector may be removed by hand or may require pressing out the plastic retainer. If the wires fit separately to the terminals, they must be carefully removed from the contacts, having first remembered or photographed the color markings. Color scheme The wires are usually standard, but it is better to double-check.
The relay body itself is removed by moving down or to the side, depending on how it is installed. Sometimes the relay is additionally fixed with a metal U-shaped bracket, which needs to be pryed off with a screwdriver and removed. If the relay is very tight, do not use excessive force to avoid damaging the ceramic terminal insulators on the compressor. A slight rocking from side to side will help loosen the oxidized contacts.
After removing the outer plastic case, you can see the internal filling. In older models, the relay may be filled with compound or have a collapsible housing. If the relay is detachable, inside you will see a coil, contacts and possibly a posistor (thermistor) in newer models. Be careful: there may be a mercury switch inside (in very old models) or simply burnt contacts.
⚠️ Attention: When removing the relay, avoid impacts and shaking. If there is a mercury sensor or a fragile posistor inside the device, mechanical stress can permanently damage the part, even if it was in good order.
For ease of diagnosis and replacement, it is often necessary to remove the relay along with the thermal protective device, if they are not combined into one unit. The thermal relay is usually a tablet or cylinder placed on one of the terminals or located nearby. Carefully remove it too in order to have full access to the contact group of the compressor for cleaning or checking.
☑️ Preparation for removing the relay
Types of relays and their differences in design
Start relays are divided into several main types, and understanding these differences will help You can quickly navigate what exactly is in your hands. The main division occurs according to the operating principle: electromagnetic, posistor and relay-thermal. Each type has its own design features and characteristic signs of malfunction.
Electromagnetic relays operate due to the current flowing through a coil, which, when the engine starts, retracts the core and closes the starting contacts. They often make a loud clicking sound when turning on and off. PTC relays use a thermistor, which is heated by current and increases its resistance, breaking the starting winding circuit. They operate silently and are considered more modern and reliable.
The table below will help you quickly classify the type of relay installed in your refrigerator by external features and markings:
| Relay type | Appearance | Characteristic sound | Marking examples |
|---|---|---|---|
| Electromagnetic | Large body, coil visible | Loud click | RTK, R-1, R-2 |
| Posistor (PTC) | Compact plastic cube | Silent or quiet crackling | PTC, 120 Ohm, 47 Ohm |
| Relay-thermal | Combined unit with “tablet” | Click + buzzing | RTK-X, MP-1 |
| Solid-state | Electronic unit with microcircuits | Absent | Electronic Start |
Also, relays differ in the number of contacts. A standard single-phase relay has three contacts corresponding to the three terminals of the compressor (common, starting, working). However, there are also two-contact relays for certain types of engines. Marking on the case often contains information about the permissible current and voltage, which is critical when selecting an analogue.
In modern refrigerators with a No Frost system and electronic control, there may be combined units where the starting relay is integrated into the common board or is a complex electronic module. In such cases, simply replacing the “box” on the compressor may not solve the problem, since the control is carried out by the complex logic of the controller.
Is it possible to install a different type of relay?
Theoretically, you can redo the connection diagram and install a posistor instead of an electromagnetic relay or vice versa, but this requires deep knowledge of electrical engineering. The factory circuit is designed for a specific type of starter, and replacing it with another type without changing the piping can lead to burnout of the compressor windings.
Diagnosing relay faults
Understanding where the relay is located is only half the battle. It is important to be able to determine whether it is really the cause of the breakdown. The most common symptom of a faulty starting device is the characteristic behavior of the compressor: it tries to start, hums for a few seconds, then a click is heard and the motor stops. After some time, the cycle repeats.
Primary diagnosis can be carried out visually and auditorily. If you hear a loud click followed by a humming noise when you turn on your refrigerator, and then another click followed by silence, this is a sure sign that the starter circuit is not opening or closing correctly. If the relay simply does not show signs of life (no click), the coil may have burned out or the posistor has collapsed.
For a more accurate check of the relay, you need to remove it from the compressor and “ring” it with a multimeter. In a working posistor relay, the resistance between the contacts should be within normal limits (usually several tens of Ohms), and when heated, it should go to infinity. The electromagnetic relay must complete the circuit when voltage is applied to the coil. If the contacts are burnt and stuck together, the engine will hum constantly until the thermal protection is triggered.
⚠️ Attention: If after replacing the relay the situation repeats, the problem may not be in the relay itself, but in the interturn short circuit of the compressor windings or jamming of the piston group. In this case, replacing the relay will only give a short-term effect.
Another sign of a malfunction is a burning smell or a melted relay body. This indicates that a current exceeding the rated current passed through the device, or a poor contact occurred. In such cases replacing the relay is mandatory, since further operation can lead to a wiring fire or complete failure of the compressor.
Replacement and installation of a new component
If Diagnostics confirmed the malfunction, it is necessary to replace it. The new component must fully correspond to the original in terms of electrical characteristics and mounting dimensions. When purchasing, pay attention to the markings, number of contacts and type of fastening. Installation is carried out in the reverse order of dismantling.
First, a thermal protection relay is put on the compressor terminals (if they have been removed), then a starting relay is put on the contacts. It is important to ensure a tight fit: the contacts should not loosen, but you should not use excessive force when putting them on, so as not to break the ceramic insulators. After installing the relay housing, the wires are connected in accordance with the previously taken photograph or diagram.
Check the secure fit of all connectors. If the wires enter the relay through separate terminals, make sure they are tight and not oxidized. If necessary, clean the contacts with fine sandpaper or alcohol. After assembling all the elements, you can attach the protective bracket or frame, if provided by the design.
After installing the new relay, do not rush to close the back cover. Plug in the refrigerator and listen. If you hear a confident start of the compressor, a smooth hum without jerks or clicks, and after a while cold appears in the chamber, the repair has been completed successfully. If the nature of the sound has not changed, a more in-depth diagnosis of the system may be required.
Do not forget that after repair, the refrigerator should operate for several hours without a full load of food, so that you can ensure the stability of its operation. Control start-up is an important step to ensure that the new part functions correctly and does not cause overheating.
Frequently asked questions (FAQ)
Is it possible to start a refrigerator without a start relay?
Theoretically, you can start the engine by forcibly closing the starting winding, but doing this is strictly not recommended. Without a relay, the engine will not be able to reach operating speeds, it will get very hot and quickly burn out, or it will trip the circuit breaker. A relay is a necessary element for the proper operation of an asynchronous motor.
Why does the relay burn out repeatedly (constantly)?
Frequent combustion of the relay indicates a system problem. This may be low voltage in the network, wear of the compressor itself (stiff piston movement), malfunction of the thermostat (frequent switching on) or the use of low-quality relay analogues with unsuitable characteristics.
Where to buy an original relay for an old refrigerator?
Original spare parts for old models (for example, Biryusa, Minsk, "ZIL") can often be found in specialized stores of spare parts for household appliances, on radio markets, or ordered through online platforms using the catalog number. It is important to know the exact model of the compressor.
How much does it cost to replace the start relay?
The cost of the relay itself varies from 500 to 2000 rubles, depending on the type and brand. If you do the work yourself, these are the only expenses. The services of a replacement technician will cost an additional 1,500 to 3,000 rubles, including travel and diagnostics.
Is it dangerous to change the relay yourself?
Replacing a relay is not very difficult if you follow electrical safety rules. The main danger is electric shock when the device is plugged in or damage to the compressor leads during careless dismantling. With the right approach, the risk is minimal.