A sudden failure of the refrigerator is always stressful, because food supplies are at risk. Most often, the unit simply stops starting, although the compressor hums, but cannot gain speed, or is completely silent when turned on. In most such situations, the culprit is the starting relay, which is responsible for starting the compressor engine.
Diagnostics and follow-up replacing the starting relay is one of the most common procedures in household repair of refrigeration equipment. This device looks like a small plastic box attached to the side or bottom of the compressor. Despite its small size, it is this that supplies the necessary impulse to start the electric motor, opening the starting winding after the speed has been reached.
If you are faced with a situation where the refrigerator clicks but does not start, or the compressor runs for only a few seconds and turns off, the problem almost certainly lies in this unit. Replacing a part on your own is within the capabilities of a home craftsman, if you follow safety precautions and strictly follow the algorithm of actions. It is important to understand that an incorrect connection can lead to combustion of the compressor windings, so accuracy is paramount here.
The principle of operation and the design of the starting relay
To make the connection correctly, you need to understand the internal logic of the operation of this element. The start relay is an electromagnetic switch that responds to the amount of current flowing through the main winding of the motor. When the refrigerator is turned on, the compressor rotor is stationary, and the starting current reaches its maximum values. It is at this moment that the relay closes the starting winding circuit, creating torque.
As soon as the compressor shaft reaches about 75% of the rated rotation speed, the current in the circuit drops. The electromagnet in the relay weakens and the contacts open, turning off the starting winding. Further operation of the engine occurs due to the main winding. Modern models often use devices of the RT or R-KTseries, which can be posistor or induction.
Induction relays work due to the movement of the core under the influence of the magnetic field of the coil. The posistor models contain a ceramic element (posistor), which, when heated by current, sharply increases its resistance, actually opening the circuit. Understanding the type of your relay is critical, since interchangeability of induction and posistor relays is not always possible and requires checking the electrical circuit of a particular compressor..
⚠️ Attention: Before starting any work on removing or installing the relay, be sure to disconnect the refrigerator from the electrical network. Working with 220V voltage in humid conditions or in a tight space in a refrigerator niche carries an increased risk of electric shock.
Structurally, the device consists of a housing, a coil, a movable heart (armature), contacts and a spring. All these elements must work in perfect synchronization. If the core sticks or the contacts burn, the startup cycle is disrupted. The compressor tries to start, hears a characteristic click, but does not rotate, and the thermal protection relay turns off the power to prevent overheating.
Fault diagnosis before replacement
Before running to the store for a new part, you should make sure that the problem is in the relay, and not in the compressor itself or the wiring. Primary diagnosis is carried out visually and auditorily. If, when you turn on the refrigerator, you hear a loud click, followed by a humming sound from the compressor that lasts 3-5 seconds, and again a click and shutdown, this is a classic symptom of a faulty starter.
Remove the back cover of the refrigerator (or remove the unit from its place if access from the rear is limited) and get to the compressor. After removing the casing from the relay, inspect it. Often traces of melting, soot or cracks are visible on the plastic case. If the relay looks charred, its performance is in question. It is also worth checking the contacts for oxidation.
For a more accurate check, you can use a multimeter in resistance measurement mode. Ring the relay contacts: in operating condition, the resistance between certain contacts should be close to zero or correspond to the technical characteristics of the model. If the device shows an open circuit or, conversely, a short circuit where it should not be, the part requires replacement.
- 🔊 A characteristic click: The sound of the relay operation is heard every few minutes, but the compressor does not start.
- 🔥 Case heating: The compressor or the relay itself becomes excessively hot after several attempts startup.
- 🧊 Lack of cold: In the refrigerator chambers, the temperature rises to room temperature, food begins to deteriorate.
- ⚡ Knocking out plugs: In rare cases, a short circuit inside the relay can lead to the operation of circuit breakers in the electrical panel.
Sometimes the cause of failure is not the relay itself, but an interturn short circuit in the compressor windings. To eliminate this option, you can carefully (with caution!) supply power directly, bypassing the relay, but this is recommended only for experienced craftsmen. For the average user, the best indicator remains the appearance of the part and the results of testing with a multimeter.
Selection of analogues and marking of devices
Starting relays are not universal devices. They are selected strictly for a specific power and type of compressor. Installing the wrong relay will result in it either not turning off the start winding (which will cause it to burn out), or not being able to turn it on (the compressor will hum, but will not start). Therefore, the search for a replacement begins with studying the markings of the old device.
The relay body is usually marked with markings, for example, RTK-1X, R-3, s (Danfoss) 101L0015 etc. The first letters and numbers indicate the series and compatibility with a certain power range. It is also important to pay attention to the number of contacts and their location. There are single-contact, two-contact and three-contact models, as well as relays with additional terminals for thermal protection.
If you find the exact one The original is not possible, you can use universal starting relays. They often have multiple pairs of contacts and are suitable for a wide range of compressors. However, their connection requires careful study of the attached diagram, since the number of contacts on a universal relay may exceed the number of wires in your refrigerator.
| Relay marking | Compressor type | Power (W) | Features |
|---|---|---|---|
| RTK-1X | Single-phase | Up to 150 | Vertical mounting, induction |
| R-3 | Single-phase | Up to 250 | Horizontal mounting, posistor |
| Danfoss 101L | Single-phase | Up to 350 | Universal, often comes complete with a thermal relay |
| PZR-3-1 | Single-phase | Up to 200 | Posistor type, compact |
When purchasing, be sure to compare not only the markings, but also the appearance of the contacts. Sometimes manufacturers change the design of the housings, leaving the electrical part the same, but there are also the opposite situations. If you are in doubt about the choice, it is better to photograph the compressor nameplate and the old relay and consult with the seller of a specialized store.
Step-by-step instructions for replacing the relay
The process of replacing the starting relay is quite simple, but requires attention to detail. The main rule is to remember or photograph the position of the wires before disconnecting them. Even if you plan to install the exact same model, the orientation of the contacts may differ depending on the manufacturer of the batch.
Start by dismantling the old device. Typically, the relay is simply slipped onto the three contacts of the compressor and secured with a metal bracket or plastic latches. Carefully remove the retainer and pull the relay down. If there are terminals on the wires, you need to disconnect them, after remembering which wire went where. Color marking is often used, but you should not rely on color alone - it is better to take a photo.
Install the new relay in the reverse order. It should fit tightly on the contacts of the compressor. If a PTC relay is used, make sure it is installed in the correct position (usually indicated by an "UP" or "UP" arrow) as gravity affects the operation of some of the mechanical parts inside. After installation, put the wire terminals on the corresponding contacts of the new relay.
☑️ Check before first start
After all connections are made, visually check the reliability of the contacts again. Wires should not dangle or touch hot parts of the compressor. Put on the protective cover (if equipped) and secure it. Now you can turn on the refrigerator.
When you turn it on for the first time, listen carefully. The compressor should start with a characteristic even hum. If you hear a clicking and humming noise again followed by a shutdown, then the problem is either an incorrect connection, or in the compressor itself, or the new relay is also defective. Normally, the refrigerator should start working and begin to gain temperature.
Connection diagram and color coding
Although the design seems simple, confusion in the wires is the most common mistake when doing DIY repairs. The standard connection diagram for a single-phase compressor assumes the presence of three main terminals: common (Common), starting (Start) and working (Run). The starting relay is connected precisely to the starting and common terminals (or working, depending on the design), closing the circuit at the start.
In most domestically produced models (Atlant, Biryusa, ZIL), the wires have the following colors: red or orange usually goes to the starting winding, white or black to the working winding, and yellow-green is grounding. However, European and Asian brands (LG, Samsung, Bosch) can use their own encoding. For example, Danfoss colors may be completely different.
If you are lost in orientation, refer to the diagram on the cover of the compressor terminal box (if it is preserved) or find the compressor model on the Internet. Incorrect connection, for example, constantly applying voltage to the starting winding, will lead to its instant burnout. Phasing in this case, it is not so important for rotation (a single-phase motor will start in any direction), but is important for the correct operation of the starting circuit.
⚠️ Attention: Do not use twists to connect wires no soldering or quality terminals. The vibration of a running compressor will quickly weaken the twist, leading to sparking, heating and possible fire. Use crimp terminals or heat-shrink soldering.
In some modern models, the relay is integrated into a common control board, and there is no separate hinged unit. In such cases, “connection” means repairing or replacing an electronic module, which requires deeper knowledge in electronics and the presence of a soldering iron. For classic refrigerators with mechanical control, the diagram described above is standard.
What to do if the contacts on the new relay do not match in distance?
If you bought a universal relay, adapters or additional wires are often included in the kit. If there are none, and the distance between the compressor pins and the relay contacts does not match, you can carefully bend the relay contacts (if they are metal and allow it), but it is better to find a model that matches the pitch of the contacts of your compressor so as not to create mechanical stress in the assembly.
Typical installation errors
Even experienced craftsmen sometimes make mistakes, let alone beginners One of the most common problems is installing the relay upside down. As mentioned earlier, many induction relays only operate in a certain spatial position. If you turn such a relay over, the armature will not fall onto the contacts under the influence of gravity, and the circuit will not open, which will lead to an overload.
Another mistake is ignoring the state of the thermal relay. Often the start relay and thermal (protection) relay are combined into one unit or located in close proximity. When changing one, it is worth checking the second. If the thermal relay is “tired” and has too wide a spread in response temperatures, the new starting element will not work correctly, constantly turning off due to overheating.
They also often forget to secure the wires. Vibration is the main enemy of electrical connections in a refrigerator. If the starting winding wire dangles, it may rub against the compressor housing or come off the terminal at the most inopportune moment. Use standard clamps or plastic ties to secure the harness.
- 🔄 Incorrect orientation: Installing the relay with the arrow not up, which disrupts the switching mechanics.
- 🔌 Bad contact: The terminals are not fully inserted or are oxidized, which causes heating and loss signal.
- 🧹 Ignoring cleaning: Installing a new relay on a dusty, dirty compressor, which impairs heat dissipation.
- 🧊 Attempting to repair the old one: An attempt to clean the contacts of a burnt out relay instead of buying a new one (effect short-term).
Do not try to revive a burnt out relay by cleaning the contacts or knocking out carbon deposits. Even if after such a procedure the refrigerator starts working, the characteristics of the spring and core are already violated. Such a relay will work from several hours to several days, after which it will fail again, possibly damaging the compressor. Saving on this part is impractical.
Checking operation after replacement
The final stage is monitoring the operation of the unit. After turning on, listen to the sound of operation: it should be smooth, without extraneous knocking, clanging or intermittent humming. The compressor should not vibrate excessively. If everything sounds normal, check the heating of the relay housing and compressor after 15-20 minutes of operation. They should be warm, but not hot.
Pay attention to the operating cycle. The refrigerator should reach temperature and turn off. If it runs continuously for more than an hour and does not turn off, perhaps the relay is selected incorrectly (too powerful or weak) or there is a freon leak, but this is another problem. A correctly selected and installed relay ensures that the motor is clearly turned on and off at the command of the thermostat.
It is also important to check whether the wire connections are hot. Carefully (so as not to get burned) touch the insulation near the terminals. If you feel intense heat, it means the contact is bad and needs to be redone. A reliable connection remains cold or slightly warm.
If after replacing the relay the problem does not disappear, and the compressor still does not start or the machine is knocked out, most likely the fault lies deeper. This could be an interturn short circuit in the windings of the compressor itself, a breakdown in the housing, or a malfunction in the wiring of the refrigerator. In such cases, independent repair becomes dangerous and requires calling a professional technician with diagnostic equipment.
Frequently asked questions (FAQ)
Is it possible to start a refrigerator without a starting relay?
Theoretically, you can start the engine by applying voltage directly to the starting winding for a short time, but operate It is absolutely impossible to have a refrigerator without a relay. Without a relay, the starting winding will burn out in a matter of seconds, since it is not designed for long-term operation. The compressor will fail irrevocably.
How much does a starting relay cost and is it difficult to find?
The cost of the relay varies from 500 to 2000 rubles, depending on the model and manufacturer. You can find them in home appliance spare parts stores or order them online based on the markings. Universal relays are cheaper and fit many models.
Why does a new relay burn out after a short time?
There may be several reasons: incorrectly selected relay power, incorrect installation (wrong side), poor contact in the circuit leading to sparking, or, worst of all, a “dying” compressor that consumes too high a starting current, overloading the relay.
What is the difference between a posistor and induction relay?
Induction ones use an electromagnet and a movable core, depending on the position in space. The posistor ones use the property of the ceramic element to heat up and lose conductivity; they are more compact and less sensitive to vibration, but can be sensitive to voltage surges.
Is it necessary to defrost the refrigerator before replacing the relay?
Full defrosting is not necessary if access to the compressor is open (usually it is at the bottom at the back). However, if the refrigerator is severely frozen and you plan to work near the evaporator or carry out long-term manipulations, it is better to defrost it so that water does not get on the electrical contacts.