The sudden stop of the compressor and the absence of the characteristic hum of a working unit often becomes an unpleasant surprise for the owner of household appliances. If at the same time the light in the chamber is on, but the engine is silent or makes only a quiet click, most likely the problem lies in the electrical circuit for starting the engine. Independent replacement of the starting relay is one of the most accessible procedures in household repairs, which does not require deep engineering knowledge, but requires accuracy and compliance with safety precautions.
It is this small component that is responsible for supplying a starting pulse to the motor winding, allowing it to overcome inertia and start rotation. Failure of this unit is a common situation faced by owners of equipment Indesit, Atlant, Beko and other popular brands. In this article, we will look in detail at how to diagnose a breakdown, choose the right spare part and replace it, restoring life to your refrigerator.
Before you begin disassembling, make sure that you have completely disconnected the device from the power supply. Working with live electrical components is strictly prohibited and poses a direct threat to life. It is also worth preparing a workplace: you will need a clean, well-lit surface where you can put the removed parts so as not to lose small fasteners.
Symptoms of malfunction and initial diagnosis
Understanding the symptoms allows you to accurately determine the problem before disassembly begins. Most often, a breakdown start relay is indicated by a specific sound: a series of clicks at regular intervals. The compressor tries to start, hums for a few seconds, then a click is heard and the motor stops. After some time, the cycle repeats.
In some cases, the engine may not make any sounds at all, remaining cold, while the relay housing may heat up. This indicates that the circuit is not closing and no current is flowing to the starting winding. For accurate diagnostics, experienced technicians use a multimeter, checking the resistance of the windings and the integrity of the contacts inside the relay itself.
- 🔊 The compressor hums for 5-10 seconds, followed by a click and stop.
- ⚡ Failure to start the engine when the backlight is working and the thermostat is working.
- 🔥 Heating of the relay housing or the appearance of a burning smell in the motor area.
- 🧊 Defrosting of the refrigerator occurs due to prolonged downtime of the compressor.
⚠️ Attention: If after several attempts to start you feel a persistent smell of burnt insulation, immediately stop trying to turn it on. Prolonged supply of voltage to a jammed or faulty motor can lead to an interturn short circuit and complete failure of the compressor.
It is important to distinguish a relay breakdown from problems with the compressor itself. If the engine hums but does not start, and an overload sound is heard, this may indicate a jammed piston group. In this case, replacing the relay will not help, and more complex repairs or replacement of the unit will be required. However, statistics show that in most cases the culprit is an inexpensive plastic block with contacts.
The design and principle of operation of the starting relay
To carry out quality repairs, you need to understand how the unit is designed. The start relay is an electromagnetic or posistor switch. In electromagnetic models, which are more often found in older refrigerators, the coil is connected in series with the working winding of the motor. When current passes, the coil creates a magnetic field that draws in the core and closes the contacts of the starting winding.
As soon as the engine picks up speed, the current drops, the magnetic field weakens, and the core, under the influence of gravity or a spring, opens the circuit. Modern models use POSITOR relays, where the role of a switch is performed by a thermoelement. When heated by current, its resistance increases sharply, actually opening the circuit of the starting winding. Both types of devices are compact and are mounted directly on the output pins of the compressor.
Structurally, the part is made in a plastic case, inside which there are copper contacts, springs and, depending on the type, a coil or ceramic disk. It is the contacts that often burn or oxidize, which leads to loss of conductivity. The switching mechanism itself may also be destroyed, which makes it impossible to break the circuit after starting, causing overheating of the windings.
Preparation of tools and selection of a new part
You do not need a complex professional tool to carry out the operation. A basic DIY kit found in most men's drawers will suffice. The main thing is to provide access to the rear of the unit and be able to safely manipulate electrical wires.
- 🔧 Screwdrivers: flat and Phillips (sizes PH1, PH2 and a 3-4 mm slot are often required).
- 🔪 Utility knife or scalpel for stripping wires (if required).
- 🧤 Dielectric gloves for protection against residual voltage.
- 📸 Smartphone for photographing the connection diagram before disassembling.
The most critical stage is choosing the right spare part. Start relays are not 100% universal. They are selected strictly according to the compressor power and the type of refrigerant. There is always a marking on the body of the old part, for example, 17.516, RTK-X or 3357. These numbers must be rewritten or photographed.
| Relay type | Application | Features | Compatibility |
|---|---|---|---|
| Electromagnetic | Old models (Minsk, Biryusa) | Position sensitive, requires vertical installation | Motors up to 200 W |
| Posistor (PTC) | Modern refrigerators | Does not depend on orientation, runs quieter | Motors of any power |
| Universal | For temporary repairs | Requires adjustment of contacts and wires | Only if the original is not available |
When purchasing, pay attention to the power range indicated on the package. If you install a relay rated for less power, it will click constantly and burn out quickly. If it is too large, the contacts may not open in time, which will lead to overheating of the engine. The ideal solution is to search for the original article according to the model of your refrigerator.
⚠️ Attention: Technical characteristics of compressors and relay compatibility may vary depending on the year of manufacture and the specific modification of the equipment. Always check the markings on the body of your part with the manufacturer's catalog data before purchasing.
Removing the old start relay
The process of removing the part begins with providing access to the compressor. To do this, the refrigerator must be moved away from the wall, turned over or carefully tilted, locking it in a stable position. Remove the rear metal or cardboard cover covering the engine compartment. It is usually secured with bolts or latches.
On the compressor you will see a round black “barrel” - this is the start relay, mounted on three pins. The wires from the thermostat and the network cable fit into it. Before tightening the relay, you need to photograph the connection diagram. The colors of the wires may differ in different models, and relying on memory is risky here.
☑️ Removal procedure
Carefully disconnect the wire terminals. In some models they may be soldered, then you will have to cut them with side cutters, leaving some room for connection. If the terminals are removable, simply pull them off. Then remove the relay itself. It may fit tightly, so rock it slightly from side to side, but without jerking sharply, so as not to damage the ceramic leads of the compressor.
After removal, inspect the inside of the relay. If you see blackened contacts, melted plastic, or smell a burning smell, the diagnosis is confirmed. Also check the condition of the pins on the compressor - they should be clean, free of oxides and carbon deposits. If necessary, clean them with fine sandpaper or an eraser.
Installing a new relay and assembling the system
Installation of the new part is carried out in the reverse order of dismantling. Make sure the new relay is in the correct orientation: there will usually be a marking on the housing UP or an arrow pointing up. This is critical for electromagnetic relays, since the core must move vertically under the influence of gravity.
Place the relay tightly onto the three pins of the compressor. It should fit tightly, without backlash. Then connect the wires to the appropriate terminals, using the photographs you took as a guide. If you have bitten the wires, connect their ends to the new terminals using reliable twisting and heat shrinking or soldering for better contact.
- 📷 Check the connection of the wires with the photo taken before disassembly.
- 🔒 Make sure that the terminals are tightly seated on the relay contacts and not dangling.
- 🧭 Check the position of the relay relative to the horizon (the UP arrow should look up).
- 🔍 Visually inspect the assembled structure for the absence of unnecessary parts or wires.
⚠️ Attention: Do not try to force the relay if it does not fit. Check the fit of the model and the angle of inclination. Excessive force can break the compressor terminals, which will turn a simple repair into an expensive replacement of the entire unit.
After connecting all the wires, replace the compressor protective cover and secure it. Make sure that the wires do not touch hot parts of the compressor and are not pinched. Now you can plug in the refrigerator. The first start may be accompanied by a longer hum until the system reaches operating mode.
Checking operation and typical errors
After replacing the relay, it is important to make sure that the refrigerator is in operating mode. During the first hour of operation, the compressor must turn off when the set temperature is reached. If it works without stopping, this may indicate a freon leak or a malfunction of the thermostat, not the relay.
One of the common mistakes is the incorrect selection of the relay type. Installing an electromagnetic relay instead of a posistor relay (or vice versa) without taking into account the features of the circuit can lead to the fact that the motor will not start or will work with overload. It is also important not to confuse the wires going to the working and starting windings.
If after replacement the situation has not changed and the compressor continues to click, the problem may be deeper. Perhaps the motor itself is faulty (turn-to-turn short circuit) or the thermostat has failed and is not sending a signal to start. In such cases, professional diagnostics are required by measuring the resistance of the windings.
Is it possible to repair an old relay rather than changing it?
Theoretically, if the relay is electromagnetic and the contacts are simply burnt, they can be cleaned with a needle file. However, this is a temporary measure. The mechanism is worn out and the problem will soon return. PTC relays cannot be repaired, since the ceramic element changes its properties irreversibly.
How long does it take to replace a starting relay?
For an experienced technician, the process takes 15-20 minutes. For a beginner who is faced with this task for the first time, including time for diagnostics, searching for tools and careful disassembly, this can take about 40-60 minutes.
Why did the new relay immediately burn out?
This can happen due to a voltage surge in the network, jamming of the compressor (the starting current was too high) or incorrect installation (incorrect orientation for electromagnetic models). It is also possible that a relay with an inappropriate power range was selected.
Where can I find the relay markings if they are erased?
If the markings on the case are not readable, you will have to look for information on the compressor model (indicated on the sticker next to it) in the manufacturers' technical tables or consult with the spare parts seller, naming the model of yours refrigerator.
Is it dangerous to operate a refrigerator with a faulty relay?
Yes, it is dangerous. Constant attempts to start create high inrush currents, which can lead to overheating of the wiring, melted insulation and even fire. In addition, this finishes off the compressor windings, bringing its complete replacement closer.