In case of a sudden stop compressor or a characteristic click, after which the refrigerator stops cooling, the first suspicious part is the start-up relay. It is this small unit that is responsible for starting the engine and protecting against overloads, and its visual identification is the first step to successful repair. Understanding what a refrigerator relay looks like allows the owner of the equipment not to get confused when looking at the internal structure of the unit and to correctly diagnose the problem.
The appearance of this element may vary depending on the compressor manufacturer, the year of manufacture of the refrigerator and the type of protection technology used. In this article, we will analyze in detail the design, color differences, markings and physical signs of malfunction so that you can accurately determine the condition of the part. Knowing these nuances will help you make the right decision: replace the component yourself or contact a specialist.
General description and location of the unit
The start-up relay is usually a compact plastic case that is attached directly to the side or lower rod of the compressor. Location parts are dictated by the need to minimize the length of the wires, connecting the relay contacts to the motor windings. Most often, to access it you need to remove the back metal cover of the refrigerator, where the motor-compressor is located at the bottom.
Externally, it is a black, white or gray plastic barrel, often with visible terminals or wires entering the body. The size of the device rarely exceeds the dimensions of a matchbox, which makes it invisible in the overall design, but critical to the operation of the system. Inside the plastic casing there is a complex mechanism that opens the circuit when overheated or overcurrent.
It is important to note that the connection to the compressor is made through three main contacts that correspond to the motor terminals. Design can be collapsible or monolithic, sealed at the factory. If you see screws or latches on the case, this indicates the possibility of internal inspection without damage, which is found in older models of equipment.
⚠️ Attention: Before any visual inspection or removal of the relay, be sure to disconnect the refrigerator from the electrical network. Working with electrical appliances under voltage is deadly.
Visual differences: thermal and electromagnetic models
When determining what a refrigerator relay looks like, it is important to understand that there are two main types of devices that differ not only in the principle of operation, but also in appearance. Electromagnetic relays are more often found in older models of refrigerators and have a characteristic design with a movable core. They are usually heavier and, when shaken, produce a ringing metallic sound.
Thermal (or posistor) relays are more common in modern technology. They are more compact, lighter and often made in the form of a small plastic cylinder or box with a posistor sticking out. Visually, they can be distinguished by the presence of a ceramic element, which, when heated, changes its resistance, opening the starting winding.
The color of the case can also indicate the type of device, although there is no single standard. Black housings are often found in relays such as RTK, R-3, R-4, which are thermal. White or gray plastic cases can hide both modern electromagnetic and combined devices. Markings on the case, such as 17A 220V or PTC, are the most reliable indicator of the type.
⚠️ Attention: Do not try to replace a thermal relay with an electromagnetic one without in-depth knowledge of circuit design. The difference in actuation currents can lead to combustion of the compressor.
Detailed inspection of the case and markings
When examining the removed device in detail, attention should be paid to the condition of the plastic. On a high-quality relay, the surface is smooth, without traces of melting or deformation. If you notice swellingblackening or a burning smell emanating from the housing, this is a direct indication of an internal malfunction. Such signs indicate that the contacts inside were overheated and could be welded.
The marking is applied with indelible paint or a laser on the side edge. The manufacturer (for example, Danfoss, Indesit, Beko), device model and electrical parameters are usually indicated there. Pay special attention to the designation of the upper limit of the cut-off current - this is a critical parameter for selecting an analogue. Code models often contain information about the type of compressor for which the relay is intended.
Connectors and terminals must be clean, without oxides or greenish deposits. Oxidation of the contacts impedes the passage of current and causes additional heating, which shortens the service life of the entire assembly. If rust is visible on the contacts, this may indicate increased humidity in the compressor niche or water ingress when washing the floor.
Table: Comparison of characteristics of different types of relays
For a deeper understanding of the differences, we provide a comparative table of the main parameters. This will help systematize knowledge about how this or that device looks and behaves under different operating conditions.
| Characteristics | Electromagnetic relay | Thermal (Posistor) relay | Combined relay |
|---|---|---|---|
| Principle of operation | Magnetic field of the coil | Heating of the posistor crystal | Combination of both methods |
| Sound when shaking | A loud knock core | Deaf or no sound | Weak knocking |
| Typical color | White, gray, black | Black, white | Black, gray |
| Position sensitivity | High (strictly vertical) | Low | Medium |
| Resource operations | High (mechanics) | Medium (wear of the posistor) | High |
The table shows that the physical properties of the devices differ significantly. Electromagnetic models are more sensitive to spatial position, so they cannot be installed on their side. Thermal analogues are more versatile, but may have a shorter lifespan with frequent power surges in the network.
Symptoms of a malfunction: what a burnt-out relay looks like
Diagnostics of a malfunction often begins with a visual inspection. If the relay looks blackened and the plastic has melted, the question “what does a working relay look like” disappears by itself - you have an obvious defect or the result of a power surge. However, often there are no external defects, and then you have to resort to other verification methods.
One of the simple methods is acoustic. A working electromagnetic relay produces a clear metallic sound when lightly tapped or shaken. If you hear a rattling sound inside, like from a broken light bulb, it means that the core or contacts are destroyed. Posistor Relays are silent when shaken, since they do not have moving mechanical parts in the classical sense.
It is also worth paying attention to the contacts. If they are covered with carbon deposits or have spark pits, this disrupts the electrical contact. In some cases, you can carefully open the case (if it is latched) and clean the contacts with a fine file, but this is a temporary measure. It is best to replace the entire assembly, since the reliability of such a restoration is questionable.
Is it possible to restore a burnt relay?
Theoretically, if you have soldering skills and knowledge of the device, you can replace the internal coil or posistor. However, given the low cost of new components and the high responsibility of the unit, restoration is not economically feasible and is risky for safety.
The process of dismantling and checking contacts
In order to finally verify the condition of the part, it must be removed. Fastening is carried out either with latches, or with a screw, or simply by a tight fit on the compressor terminals. Gently rock the device from side to side to remove it from the pins. Do not use excessive force to avoid damaging the leads of the compressor itself.
After removal, inspect the seat on the compressor. There should be no traces of burning or oxidation. If you plan to test with a multimeter, you need to “ring” the circuit. In normal condition, the circuit should be closed (resistance close to zero). If the device shows a break (one on the screen), it means that the spiral inside has burned out or the contacts do not close.
When installing a new or tested old relay, make sure that it is seated tightly and all the way. Orientation the device must strictly correspond to the factory one: usually the “UP” marking or the arrow should point up. Incorrect installation may result in the protection not working at the right time or starting the engine will be impossible.
☑️ Checklist for checking the relay
Frequently asked questions and nuances replacement
Many users wonder whether it is possible to use a relay from another refrigerator. In most cases, this is possible if the electrical parameters and the type of compressor match. However, there are no universal relaysand an attempt to install a device with a different cut-off current may result in the compressor either not starting or burning out from overload.
Another important aspect is the cooling time. After several attempts to start or activate the protection, the thermal relay requires time (usually 3-5 minutes) for the posistor to cool down. If you try to turn on the refrigerator again immediately after the click, it will not start. This is not a malfunction, but the normal operating mode of the thermal protection.
When purchasing a new part, pay attention to the number of contacts. The standard relay has three terminals for the compressor, but there may be additional terminals for alarm or fan control. If your refrigerator does not have such functions, additional contacts may simply remain free, but it is better to look for a complete analogue.
Can the relay click but not turn on the compressor?
Yes, this is a classic symptom. A click means that the relay mechanism is trying to work, but either the contacts inside are burnt and do not conduct current, or the compressor piston is jammed, and the relay immediately opens the protection circuit.
How often do you need to change the refrigerator relay?
The relay is a part with a limited resource, but with a stable voltage in the network it lasts 5-10 years or more. Frequent replacements (once a year) indicate problems with the power supply or the compressor itself.
Does dust affect the operation of the relay?
Dust itself is not dangerous, but if it is mixed with moisture and oil, a conductive layer can form, causing current leaks or short circuits. Regular cleaning in the compressor area prolongs the life of the unit.
Why does the new relay get hot?
Slight heating of the housing during operation is acceptable, since current passes through it. However, if the case becomes too hot (it is impossible to hold your finger), this is a sign of overload or incorrect selection of the model.
Is it possible to operate a refrigerator without a relay?
Absolutely not. Without a starting relay, the compressor will not start (it will hum), and without a protective one, it may burn out at the first power surge or jam.