A modern refrigerator is a complex unit in which each unit performs a strictly defined function, ensuring safety products. When the compressor stops starting or operates with intermittent clicks, the first thing experts suspect is the start protection relay. It is this small but critical component that controls the engine starting and protects it from overloads, preventing failure of the entire system.
Understanding this What is the relay in the refrigerator responsible for?will help you diagnose the problem yourself and, perhaps, avoid an expensive call to a repairman. In this article, we will analyze in detail the structure of this element, consider the symptoms of its malfunction and provide step-by-step instructions for replacement.
Without proper operation of this component, normal circulation of the refrigerant is impossible, since the motor-compressor simply cannot overcome the inertia of rest. If you hear a hum, but the refrigerator does not cool, or notice that the unit constantly clicks and turns off, the problem most likely lies here.
The operating principle and main functions of the start-up protection relay
The start-up protection relay is an electromechanical device that is installed directly on the compressor housing. Its main task is to briefly connect the starting winding of the electric motor at the moment of starting, when maximum torque is required. As soon as the rotor reaches the required speed, the relay turns off the starting winding, and the engine continues to operate on the main winding.
The second, no less important function is overcurrent protection. Inside the device there is a bimetallic plate that heats up when an electric current passes. If the current exceeds the rated values due to jamming of the compressor or a power surge, the plate bends and opens the circuit, de-energizing the unit. This function prevents burning of the motor windings and fire hazards.
There are several types of such devices, and the principle of their operation can vary. The most common are induction (electromagnetic) relays, where the contacts are closed due to the magnetic field created by the current in the coil. There are also thermal relays, the operation of which is based solely on heating a bimetallic plate, and electronic analogues, which are gradually replacing mechanics in modern models.
It is important to understand that starting relay is a consumable material that wears out over time. Contacts may burn, springs may lose elasticity, and bimetallic plates may become deformed. Regular on and off cycles create a load that the device can withstand for years, but not indefinitely.
Types of relays and their design features
The variety of refrigeration equipment has given rise to many modifications of starting protection devices. Understanding the type of relay you have is essential to selecting the correct part. The main division occurs according to the principle of operation and method of fastening.
Induction relays are most often found in old models of Soviet-made refrigerators and some modern units with piston compressors. They are based on a solenoid, which retracts the core during starting current, closing the contacts of the starting winding. When the motor accelerates, the current drops, and the core, under the influence of gravity or a spring, returns to its original position, opening the circuit.
Thermal relays, often combined with starting relays in the same housing, use bimetal heating. They are more inert, but reliable under unstable voltage conditions. In modern systems, posistor (solid-state) starters are often used. In them, the role of a switch is played by a thermistor (posistor), which, when heated by current, sharply increases its resistance, actually turning off the starting winding.
Below is a table that helps differentiate the main types of devices according to their characteristics:
| Relay type | Principle of operation | Characteristic feature | Where it is used |
|---|---|---|---|
| Induction | Electromagnetic retraction | Clear click when starting | Old and medium models |
| Thermal | Bimetallic plate heating | Overheat protection | Combined devices |
| Posistor | Change resistance | No moving parts | Modern refrigerators |
| Electronic | Microprocessor control | Smooth start, silence | Inverter systems |
When replacing a part, it is extremely important to pay attention to markings and compatibility. Universal relays does not exist, although some models may fit a whole line of compressors. An incorrectly selected device may not start the motor or, worse, not protect it in an accident.
Is it possible to install a relay from another brand of refrigerator?
Technically possible if the electrical characteristics (operation current, voltage) and mounting dimensions match. However, manufacturers often use unique connectors and housing shapes, so it is better to look for the original spare part number or a complete analogue in the catalog.
Main signs of a faulty start relay
Diagnosing a fault often begins with carefully listening to the operation of the unit. If you notice that the refrigerator is humming, but no cold is produced, or you hear frequent clicks at intervals of several minutes, this is a sure sign of a problem with the starter.
Among the most common signs are:
- ⚡ The compressor tries to start, a click is heard, but the motor immediately stalls, and the cycle repeats after a certain time.
- 🔥 The compressor housing or the relay itself becomes very hot, you can smell burning or melted plastic.
- ❄️ The refrigerator compartment does not cool the food, although the light inside is on and the fan (if any) is working.
- 🔌 Upon visual inspection, the relay contacts are visible carbon deposits, oxidation or melting of the plastic.
Sometimes the refrigerator may not turn on at all. In this case, the relay could “stick” in the open state or burn out completely, breaking the electrical circuit. It is also worth checking whether the circuit breaker in the panel is knocked out when you try to turn on the refrigerator - this may indicate a short circuit inside the relay.
⚠️ Attention: If you hear a loud cracking sound or see sparking when you turn on the refrigerator, immediately unplug the appliance. Operation in this condition can lead to a wiring fire or complete combustion of the compressor.
You should not ignore even weak signs of unstable operation. Timely replacement an inexpensive part will be saved by an expensive motor-compressor. If the relay does not perform its protective function, the compressor may operate in overload mode, which drastically reduces its resource.
Diagnostics: how to check the relay with a multimeter
Before going to the store for a new spare part, you need to make sure due to a malfunction of the old device. To do this, you will need a multimeter (tester) and a minimum set of tools. Remember that all work is carried out only with the refrigerator completely disconnected from the power supply.
Remove the rear protective cover at the bottom of the refrigerator where the compressor is located. Carefully disconnect the wires and remove the relay from the compressor contacts. Usually it is simply put on three pins and secured with a bracket or plastic clip. Visually inspect the housing: the presence of cracks, burning or traces of moisture indicates the need for replacement without further checks.
To check the continuity of the circuit, perform the following steps:
- Switch the multimeter to the continuity or resistance measurement mode.
- Identify the relay contacts (usually there are three or four: common, starting, working and grounding).
- Ring the circuit between the contacts. In the normal state, the resistance should be close to zero (for closed contacts) or infinite (for open contacts).
- Shake the relay next to your ear: if a ringing is heard, it means that the internal mechanism is destroyed or the core has broken off.
Pay special attention to checking the posistor if you have a modern device. Its resistance should increase as it heats up. In a cold state it is several tens of ohms. If the device shows zero or infinity in both cases, the part is faulty.
Step-by-step instructions for replacing the relay with your own hands
Replacing the start-up relay is one of the most accessible procedures for a home craftsman. It does not require special soldering skills or complex equipment if the right spare part is selected. The main thing is to follow safety precautions and the sequence of actions.
First, make sure that the refrigerator is unplugged for at least 30 minutes. This is necessary so that the compressor cools down and the refrigerant is redistributed throughout the system. Then remove the cardboard or plastic cover covering the engine compartment. It is usually secured with latches or bolts.
Use the following checklist for safe replacement:
☑️ Replacing the start relay
Carefully disconnect the block with wires from the relay. Remember or take a photo of which wire is connected where, as color markings may vary from manufacturer to manufacturer. Remove the retaining bracket or strip holding the relay to the compressor housing.
Install the new relay, making sure it is firmly seated on the compressor contacts. The orientation of the device must strictly correspond to the markings (usually on the case there is an arrow "UP" or "TOP" pointing up). Connect the wires according to your photo. Make sure the connections are secure and not loose.
⚠️ Warning: Never attempt to operate the refrigerator with the engine compartment protective cover removed. This disrupts the correct heat exchange of the compressor and creates a risk of electric shock.
After assembly, plug in the refrigerator. For the first few minutes it may work louder than usual - this is normal, it is in the process of reaching the mode. If after 10-15 minutes the freezer compartment begins to cool, and the compressor runs smoothly, without frequent stops, it means the replacement was successful..
Frequent errors in diagnostics and repairs
Even experienced professionals can make mistakes, not to mention beginners. One of the most common problems is trying to clean the contacts of an old relay with sandpaper. This is strictly forbidden, since the geometry of the contact pad and the special coating are violated, which will lead to rapid repeated failure.
Another mistake is ignoring the cause of the failure. If a relay burns out, it rarely happens on its own. Often the reason is the aging of the compressor itself, which begins to consume increased current, or problems with the voltage in the network. Installing a new relay on a worn motor will only give a temporary effect.
Also, users often confuse the relay with a thermostat or defrost sensor. The symptoms may be similar (the refrigerator is not cooling), but replacing the relay will not help in this case. Always carry out comprehensive diagnostics of all components.
Remember that The reason for frequent relay burning may be a malfunction of the compressor itself, for example, interturn short circuit of the windings. If the new relay burns out after a short time, you need to call a professional to deeply diagnose the motor.
Is it possible to temporarily start a refrigerator without a relay?
Technically, you can start an asynchronous motor by forcibly applying voltage to the starting winding, but doing this at home is extremely dangerous and impractical. Without a protective mechanism, the compressor can burn out in a matter of seconds due to any malfunction. In addition, without a relay, the engine will not be able to reach operating mode and will hum, overheating.
How much does it cost to replace a relay in a service center?
The cost consists of the price of the spare part itself and the work of the technician. The relay itself is inexpensive, usually from 500 to 2000 rubles, depending on the model. Replacement work takes 15-30 minutes, but calling a technician and diagnostics can cost more than the part itself. Therefore, independent replacement is often economically justified.
Why does the relay click, but the refrigerator does not turn on?
The click means that the relay is trying to work, but the compressor does not start. This may indicate that the relay is working properly, but cannot close the contacts due to burnout, or the compressor is jammed. It is also possible that the relay turns off the power due to a short circuit in the motor windings.