Sudden stoppage of operation refrigeration chamber or the absence of the characteristic hum of the motor often indicates a failure of the trigger mechanism. It is starting relay responsible for starting the engine and its normal operation in normal mode. If this small element burns out, the compressor may hum, but not start, or turn on only for a split second.
Independent replacement of this part is one of the most common and affordable types refrigerator repair, which does not require calling a technician. However, to successfully restore the functionality of the equipment, it is necessary to accurately determine the type of faulty unit and select a compatible analogue. An error in selection can lead to repeated breakdown or even burning of the motor windings.
In this article we will analyze in detail the design of starting relays, methods for diagnosing them and the algorithm for selecting a new part. You will learn how to distinguish an induction device from a posistor device, what parameters are critical when purchasing, and how to safely make the replacement yourself.
Types of starting relays: design and principle of operation
Before looking for a replacement, you need to understand what type of device is installed in your unit. In household refrigerators, there are most often two main types: induction (electromagnetic) and posistor (thermal). Induction relay works by electromagnetic induction: when voltage is applied, current passes through the coil, creating a magnetic field that pulls up the core and closes the starting winding.
As soon as the engine picks up speed, the current drops and the core, under the influence of gravity, returns to its original position, opening the circuit. Such devices are often marked RT (Relay Current) and R-1, R-2. They are more sensitive to the position of the refrigerator and require strictly vertical installation. Posistor relay operates differently: inside the case there is a ceramic element (posistor), which, when heated by current, sharply increases its resistance, actually breaking the starting winding circuit.
You can visually distinguish them by their appearance and number of contacts. Induction models often have a lever or movable core, visible when the case is opened, while posistor models are a monolithic block with three contacts. Some modern models can be combined, combining the functions of starting and thermal protection.
⚠️ Attention: Never try to use an inductive relay instead of a posistor relay (and vice versa) without a deep understanding of the circuit. Despite similar functions, their electrical characteristics and operating logic are fundamentally different, which can lead to a short circuit.
Choosing the right type is 90% of the success of the repair. If you buy a device with the wrong operating principle, the compressor will either not start or will work in emergency mode, quickly overheating. Always check the labeling of the old device with the manufacturers' catalogs.
Diagnosing a fault before purchasing
Purchasing a new part without an accurate diagnosis can be a waste of money, since symptoms of a non-working compressor may indicate other problems. The first step should always be visual inspection listening to the operation of the motor. If when you turn on you hear a quiet hum, a click, and then silence again, this is a classic sign of a malfunction of the starting mechanism or jamming of the compressor.
For a more accurate check, it is necessary to dismantle the relay and inspect its insides. Often carbon deposits or melting are visible on the contacts, which indicates overload. You can also check the integrity of the windings with a multimeter in continuity mode. If the circuit does not ring or, on the contrary, shows a short circuit, the part definitely requires replacement.
- 🔍 Check the integrity of the housing: the presence of cracks or traces of soot indicates an insulation breakdown or overheating.
- 🔌 Inspect the contacts: oxidation or burning of the terminals disrupts the transmission of current to the motor windings.
- 🧲 Test the moving parts: in electromagnetic relays, the core must move freely and not be stuck.
It is also important to check the compressor itself by ringing its windings. If the resistance between the motor contacts approaches zero or infinity, the problem may lie deeper than just the relay. In this case, replacing the starting device will not help, and more complex repairs or replacement of the unit will be required.
Criteria for choosing a compatible model
When looking for a replacement in a store or on the spare parts market, the key parameter is compressor power. Starting relays are selected strictly for engine power, measured in watts (W) or horsepower (hp). Using a relay designed for a lower power will lead to its rapid burnout, and a higher one will make it impossible to start the engine.
The second important criterion is Bore hole diameter and the location of the contacts. Even if the electrical characteristics match, the relay may not physically fit onto the compressor rod or connect to the contact group. Manufacturers often use unique body shapes, so there are few universal solutions here.
Pay attention to the manufacturer of the original part. For refrigerators Atlant, Biryusa i Indesit relays of the RT or RPK series are often used, which have their own specific modifications. For technology LG, Samsung i Beko posistor models with three contacts are more often used, sometimes combined with a thermal relay in one housing.
If you cannot find an exact analogue, you can use universal starting relays. They are suitable for a wide power range and have flexible leads that can be adapted to suit your circuit. However, such devices are considered a temporary solution and may operate less stable than original parts.
Comparative table of popular relay models
To simplify your search, below is a table with the main characteristics of common types of starting devices. This data will help you navigate the assortment and understand what exactly is required for your equipment model.
| Relay type | Series/Marking | Compatible brands | Features |
|---|---|---|---|
| Induction | RT-X, RT-K | Atlant, Minsk, Biryusa | Works only in a vertical position, sensitive to vibration |
| Posistor | RPK, 112563 | Indesit, Ariston, Stinol | Compact, less sensitive to tilts, durable |
| Combined | PTC Relay + Overload | LG, Samsung, Beko | Contains a starting and thermal relay in one housing, 3 contacts |
| Universal | 4500-4510 | Various (Chinese) | Requires adaptation of contacts, suitable for a wide range of powers |
As can be seen from the table, the variety of models is large, and it is quite easy to confuse them. Always keep the old part in front of you when ordering a new one. Even series with the same name may have differences in the length of the rod or the shape of the terminals.
Instructions for replacing the start relay
The replacement process does not require special equipment, except for a screwdriver and, possibly, pliers. The main safety rule is total disconnection from the electrical outlet. Don't just unplug the socket, but make sure there is no voltage on the wires if you plan to touch the internal contacts.
First remove the rear protective cover of the refrigerator to gain access to the compressor. The relay is usually mounted on the side or bottom of the compressor and secured with a bracket or plastic clips. Carefully disconnect the wires, having first memorized or photographed the connection diagram.
☑️ Relay replacement algorithm
Installation of the new element is carried out in the reverse order. Make sure the relay is tight and not loose. If using an induction model, make sure it is positioned strictly vertically (usually the "UP" marking should face up). After assembly, turn on the refrigerator and listen: the startup should proceed smoothly, without unnecessary clicks and buzzing.
⚠️ Attention: If, after replacing the relay, the compressor hums and clicks again, immediately turn off the device. Perhaps the problem is not in the relay, but in the motor itself (turn-to-turn short circuit) or in the wiring. Further switching on can finish off the compressor.
What to do if the new relay does not fit properly?
In some cases, you can carefully bend the contacts or use an adapter if you are confident in your abilities. However, it is better to find a model with an identical mount, since poor contact will cause sparking and heating.
Common mistakes when choosing and installing
One of the most common mistakes is ignoring the thermal relay. Often the starting and thermal relays are sold separately, but fail together. If you replace only the starting part, leaving the old thermal part, it may trigger falsely or, conversely, not protect the motor from overheating.
Another mistake is using a relay with a higher current threshold “just in case.” This leads to the fact that the relay does not open the starting winding in time, and it burns out. Cut-off current must strictly comply with the compressor's passport data.
Also, users often forget to clean the compressor contacts from oxides before installing a new relay. Even a new part will not work correctly if there is a layer of oxide or dirt on the mating pins of the motor. Wipe them with alcohol or fine sandpaper before installation.
FAQ: Frequently Asked Questions
Is it possible to start a refrigerator without a relay?
Technically, you can start a compressor without a starting relay by applying voltage directly to the starting winding for a short time, but this requires skill electrician and carries the risk of electric shock or motor damage. For constant operation, a relay is necessary.
How much does a starting relay for a refrigerator cost?
The price depends on the type and brand. Simple induction relays cost from 300 to 800 rubles. PTC and combined models for imported refrigerators can cost from 1000 to 3000 rubles. Universal analogues are usually cheaper than the originals.
Why does the relay burn out?
The main reasons: power surges, compressor wear (slow running), frequent power outages (the compressor does not have time to cool down and equalize the pressure) or factory defects of the part itself.
Where to find relay marking?
The marking is applied to the relay body (often on the side or top) and on the compressor nameplate. Look for the designations for power (W or HP), voltage (V) and frequency (Hz). The manufacturer's code is also important.
Is it necessary to change the thermal relay together with the starting one?
It is advisable to change both elements, especially if they are in the same case or sold as a set. The thermal relay is the engine's insurance, and its malfunction can lead to expensive repairs of the compressor.