A sudden stop in the operation of a refrigeration unit often takes you by surprise, but in most cases the reason lies in the failure of one of the components of the motor's electrical circuit. If you hear that the compressor hums but does not start, or, conversely, clicks and immediately goes silent, most likely the problem lies in the starting system. It is starting relay responsible for supplying the initial impulse to the motor windings, allowing it to switch to operating mode.
Independent replacement of this element is a real task for a home craftsman who has basic skills in working with electrical appliances. You do not have to call a specialist for such a procedure, since the relay device is quite simple, and the cost of a new part is not comparable to the cost of repairs at a service center. The main thing is to observe safety precautions and strictly follow the algorithm of actions so as not to damage the expensive compressor.
In this article we will analyze in detail how to properly dismantle the old starter, how to check its functionality and how to connect a new element. You will learn about the differences between induction and posistor models, and also get answers to common questions that arise when repairing household appliances.
The operating principle and design of the starting relay
To understand how to connect a refrigerator starter, you need to understand the physics of the process. A single-phase asynchronous motor installed in a compressor cannot start on its own; it requires a rotating magnetic field created by the starting winding. Starting relay temporarily connects this winding to the network, and as soon as the rotor picks up speed, turns it off.
There are two main types of devices that are widely used in modern and old refrigerators. The first type is an induction relay, where the contacts are closed due to the electromagnetic force generated when current passes through the coil. The second type is positor relay, operating on the basis of thermal expansion of a special material (posistor), which changes resistance when heated.
- 🔹 Induction models are distinguished by the presence of moving contacts and a coil; they are more sensitive to voltage imbalances.
- 🔹 PTC elements do not have moving mechanical parts, which makes them more reliable and durable.
- 🔹 Both types of devices are often combined with a thermal protection relay that turns off the motor when overheated.
It is important to understand that connection diagram depends on the type of your motor and relay designs. An installation error can lead to burnout of the compressor windings, so always check the markings before replacing. If you are not confident in your abilities, it is better to consult with a specialist or carefully study the product passport.
⚠️ Attention: Before starting any work on replacing the starter, be sure to disconnect the refrigerator from the electrical network! Working with 220V voltage without taking precautions is life-threatening.
Modern models are often equipped with combined units, where the starting and thermal relays are located in the same housing. This simplifies replacement, but requires a more careful selection of an analogue. When choosing a spare part, pay attention to the engine power and the location of the contacts.
Why does the relay burn out?
The main reason for the failure of the starting relay is wear of the contacts or aging of the posistor. Also, frequent power surges in the network can lead to sticking of contacts or thermal destruction of the element. Sometimes the relay burns out due to the compressor jamming when the starting current becomes too high.
Fault diagnosis before replacement
Before buying a new part, you should make sure that this is the problem. Often the symptoms of a faulty starter are confused with a breakdown of the compressor itself. If the motor hums but does not start, and after a few seconds a click is heard and the hum stops, this is a sure sign that the starting winding is not receiving an impulse.
For accurate diagnosis, it is necessary to remove the relay from the compressor casing. It is usually mounted on the side of the motor and covered with a plastic cover. Carefully remove the clips and remove the device. A visual inspection can tell a lot: a blackened case, melted contacts or a characteristic burning smell indicate a breakdown.
If there is no external damage, you can check with a multimeter. For posistor models, the resistance should be within normal limits (usually several tens of Ohms), and when heated, it should go to infinity. Induction relays are checked for contact closure and coil integrity.
| Fault type | Symptoms | Probable cause | Test method |
|---|---|---|---|
| Break circuit | The compressor is silent, the refrigerator does not work | The coil or posistor has burned out | Dial test with a multimeter |
| Sticking contacts | Humming, starting with difficulty, overheating | Soot on contacts, wear | Visual inspection, cleaning |
| Mechanical damage | Cracks, chips of the case | Impact, fall, aging of plastic | Visual inspection |
| Thermal relay malfunction | Short operating cycle, shutdown | Deformation of the bimetallic plate | Checking heating and operation |
In some cases the malfunction may not be caused by the relay itself, but by problems with the wiring or oxidation of the terminals. Carefully inspect the connectors and wires leading to the compressor. If oxide is visible on the contacts, clean them with fine sandpaper before installing a new element.
Preparation of tools and selection of an analogue
For a successful replacement, you will need a minimum set of tools, which is found in every master’s home. The main attention should be paid to choosing the right spare part, since there are practically no universal solutions here. Each manufacturer uses specific configurations of mounts and contacts.
It is best to take the old relay with you to the store or take a close-up photograph of its markings. The case is usually marked with a model code, which can be entered into a search engine or reported to the seller. If the exact model is not available, look for a complete analogue in terms of electrical characteristics and geometric dimensions.
- 🛠️ Flat-head screwdriver for removing protective covers and terminals.
- 🔧 Pliers or pliers for carefully removing connectors.
- 🧹 Fine sandpaper or needle file for cleaning contacts.
- 📸 Smartphone for photographing the connection diagram before disassembling.
When purchasing, pay attention to the condition of the contacts of the new relay. They must be clean, without traces of oxidation or mechanical damage. If you buy a used part, make sure that there is no moisture or foreign objects inside.
⚠️ Attention: Do not try to use a relay from another type of refrigerator “by eye”. The difference in the actuation current can lead to the relay not turning off the starting winding, and it will burn out in a matter of seconds.
If you order a part online, carefully study the reviews and description. Make sure the seller indicates compatibility with your refrigerator model. Sometimes minor modifications to the case or the use of adapters are required, but it is better to avoid such situations.
Step-by-step instructions for replacing the starter
The replacement process begins with completely disconnecting the refrigerator from the network. Wait 5-10 minutes for the capacitors to discharge and the pressure in the system to stabilize. Slide the refrigerator to gain access to the rear wall where the compressor is located.
Remove the compressor protective cover, if equipped. It can be secured with latches or screws. You will see a black metal cylinder - this is a motor, and on the side or top of it there is a plastic box - this is our desired device. Carefully remove the clamp or bend the bracket holding the relay.
☑️ Algorithm for replacing the relay
Now you need to disconnect the wires. In modern models, the relay is simply removed from the compressor pins along with the wire block. In older models, the wires may be connected directly to the relay terminals. In this case, proceed carefully so as not to damage the insulation.
Install the new relay in the reverse order. Make sure it is firmly in place and the pins are fully seated in the connectors. If the relay is inductive, it is important to observe the orientation (usually the “UP” arrow should face up), since it works under the influence of gravity.
After installing all the elements, put on the protective cover and turn on the refrigerator. In the first seconds, listen to the engine. It should start smoothly, without buzzing or extraneous clicks. After 10-15 minutes, check whether the evaporator has begun to cool.
Action diagram:1. Turn off the power.
2. Remove the casing.
3. Remove the terminal block.
4. Remove the old relay.
5. Install a new relay.
6. Fix and assemble.
Features of connecting different types of relays
Connection induction relay requires strict verticality. Inside such a device there is a core, which, under the influence of current, is drawn into the coil and closes the contacts. If you install it horizontally or upside down, the core may jam, and the starting winding will remain on constantly.
Posistor relays do not have this drawback, since they have no moving parts. However, they have their own peculiarity: after turning off the power, the posistor requires time (about 2-3 minutes) to cool down and restore conductivity. If you have just turned off the refrigerator, do not turn it on immediately - let the relay cool down, otherwise the start-up will not happen.
- 🔸 Induction relays are often marked with voltage and current (for example, 127V/220V).
- 🔸 PTC elements are marked with an alphanumeric code (for example, RTK-1, R-3).
- 🔸 Combined blocks may have additional contacts for temperature sensors.
When replacing an old Soviet relay with a modern analogue, an adapter or a slight modification of the seat may be required. The main thing is to ensure reliable electrical contact and mechanical fixation. Do not allow the relay to vibrate while the compressor is operating.
⚠️ Attention: The technical characteristics of the relay (cut-off current, response time) may vary between different manufacturers. Always check the parameters of the new relay with the requirements of your compressor specified in the technical documentation.
If you are changing the relay on an imported refrigerator, pay attention to the grounding system. In some models, the relay body can act as a grounding element, and lack of contact with the metal frame of the compressor will lead to incorrect operation.
Can the relay be repaired?
In theory, the inductive relay can be disassembled, cleaned the contacts and reassembled. However, the tightness of the housing is broken, and the reliability of such operation will be low. PTC relays cannot be repaired - only replacement.
Checking operation and common errors
After replacing the starter, it is necessary to carry out a test run of the system. Turn on the refrigerator and immediately notice the sound of the motor running. A smooth hum without metallic clanging indicates correct installation. If the motor hums but does not start, immediately turn off the device from the network.
A common mistake is to ignore the state of the contacts on the compressor itself. If the pins are oxidized or have carbon deposits on them, the new relay will perform poorly or fail quickly. Before installing a new part, wipe the contacts with alcohol or strip them.
Another common mistake is using a relay with the wrong actuation current. If the cut-off current is too high, the relay will not turn off the starting winding in time, which will cause it to burn out. If it is too small, the compressor simply will not start.
Be sure to check the operation of the thermal relay if it is part of the unit being replaced. To do this, you can simulate overheating (carefully!), but it is better to trust the factory settings if you are confident that the compressor is working properly. The thermal relay should be triggered when the temperature of the motor housing critically increases.
Why does the refrigerator not turn on after replacing the relay?
There may be several reasons: the wires are connected incorrectly (phase and zero or starting winding are reversed), the new starter itself is faulty (defective), or the problem is deeper - the compressor is faulty (interturn short circuit) or thermostat. Also check for voltage in the socket.
Is it possible to use a relay from another refrigerator?
You can use a relay from another refrigerator only if their electrical characteristics (current, voltage, type) and geometric dimensions completely match. Visual similarity does not guarantee compatibility.
How often do you need to change the starting relay?
The starting relay is a resource part, but with a stable voltage in the network, it lasts as long as the compressor itself (10-15 years or more). Frequent replacement is required only in case of constant power surges or overloads.
Is it dangerous to operate a refrigerator with a faulty relay?
Yes, it is dangerous. A faulty relay may not turn off the start winding, resulting in overheating and a fire, or the compressor will constantly try to start, drawing huge current, which can cause a wiring fire.
What should you do if the relay is constantly clicking?
A constant clicking (cycling) indicates that the compressor is trying to start, but can't. This may be due to a faulty relay, low voltage in the network, or, worse, jamming of the compressor piston group.