A sudden stop of the compressor or characteristic clicks when trying to start the refrigerator often indicate a failure of the start relay. This small but critical element is responsible for supplying voltage to the motor windings at the moment of start. If the relay is burnt out or stuck, the motor will not be able to start and the chamber will stop cooling, creating a risk of food spoilage.
Replacing this component yourself is a task within the reach of a DIYer with basic tool skills. The main thing is to strictly follow safety precautions and correctly determine the type of device installed. In this article we will analyze all the stages of diagnostics, dismantling the old part and connecting a new start relay to the compressor of your refrigerator.
Before starting the repair, you need to make sure that the problem lies in the relay, and not in the compressor itself or the wiring. Incorrect diagnosis can lead to the purchase of unnecessary parts or, worse, damage to working equipment. Carefully study the signs of malfunction so as not to waste time and money.
Diagnostics and signs of relay malfunction
The first sign that start protection relay has failed is the characteristic sound of the refrigerator. You may hear a loud click, followed by the hum of the motor for a few seconds, and then another click and silence. This means that the relay is trying to start the compressor, but cannot, and the thermal protection is triggered, opening the circuit.
Visual inspection can also tell a lot about the condition of the part. If traces of melting, soot, or a burning smell are visible on the relay housing, replacement is necessary immediately. Sometimes the problem lies in oxidation of the contacts, which requires cleaning or completely replacing the unit to restore normal operation of the system.
You can use a multimeter for an accurate check. By ringing the contacts of the coil and the moving core, you will determine the integrity of the electrical circuit. If the device shows an open or short circuit, the part is faulty.
⚠️ Attention: If the compressor hums but does not start, do not keep the refrigerator plugged in for more than 10-15 seconds in diagnostic mode. Prolonged operation of the motor in an inhibited state can lead to inter-turn short circuit of the windings and expensive motor repairs.
It is also worth paying attention to the temperature of the relay housing. If it becomes hot after switching on for a short time, this is a sure sign of an overload or an internal fault in the contact group. In such cases, further operation without replacing the component is impossible.
Types of starting relays and their design
Modern and old refrigerators use two main types of starting devices: induction (electromagnetic) and posistor (thermal). Understanding the difference between them is necessary for the correct selection of spare parts. Induction relay works due to the electromagnetic force, which draws in the core during the starting current, closing the contacts of the starting winding.
Posistor relays, more common in modern technology, use a ceramic element (posistor), which is heated by the passing current and changes its resistance. When heated, it actually breaks the starting winding circuit, leaving only the main winding to work. This is a more reliable and simple design that does not have moving mechanical parts.
You can visually distinguish them by their appearance and markings. Induction models often have a metal case or a massive plastic block with a visible coil inside, while posistor models are a compact plastic barrel or box with one or two terminals.
Can you change the types of relays?
It is technically possible to adapt a relay of another type using adapters or changing the connection diagram, but this requires deep knowledge of electrical engineering. The factory design is designed for a specific type of start-up, and experiments can lead to combustion of the compressor.
It is important to consider that some models may be universal, but most are designed for a strictly defined compressor power range. Installing a relay with unsuitable characteristics will either make it impossible to start or burn out the starting winding of the engine.
Necessary tools and preparation
To perform work on replacing a relay, you will need a minimum set of tools that can be found in any home. The main requirement is safety and accuracy of actions. Before starting work, be sure to disconnect the refrigerator from the electrical outlet by unplugging the plug from the socket.
You will need the following tools and materials:
- 🛠️ Screwdrivers (Phillips and flat) for removing the casing and clamps.
- 🔧 Pliers or pliers for fixing the wires.
- 🧹 Sandpaper or alcohol for cleaning contacts.
- 🧤 Dielectric gloves for protection against residual current.
Prepare the workplace: provide good lighting and access to the back wall of the refrigerator. If the compressor is hot, allow it to cool for 30-40 minutes before disassembling. This will reduce the risk of burns and make it easier to work with plastic elements that can become brittle when heated.
☑️ Checking readiness for repair
It is also recommended to photograph the connection diagram of the old relay in advance so as not to get tangled in the wires during assembly. The color marking of the wires may differ in different models, so a visual fixation of the initial state will be extremely useful.
The process of dismantling the old relay
Access to the start relay is through the protective casing at the bottom of the refrigerator, where the compressor is located. Remove the back panel by unscrewing the mounting screws. In some models, the panel may be held on by latches that require careful release with a flat-head screwdriver.
After removing the casing, you will see a compressor with a relay attached to its rod or side. Carefully remove the retaining bracket or clamp holding the device in place. Be careful not to damage the associated wires and insulation.
Disconnect the wire terminals from the relay contacts. Remember or sketch which wire is connected where. Usually the wires are color coded, but it's best to double check the connections. The old relay is simply removed from the compressor pins by lightly rocking.
| Element | Function | Fault symptom | Action |
|---|---|---|---|
| Starting winding | Starting the engine | Open circuit | Replacing the relay |
| Working winding | Maintaining operation | Short short circuit | Compressor repair |
| Posistor/Coil | Current switching | Lack of resistance | Relay replacement |
| Contact | Transmission voltage | Oxidation, carbon deposits | Cleaning or replacement |
If oxidized carbon deposits remain on the compressor pins, carefully clean them with fine sandpaper or a rag soaked in alcohol. Clean contacts will ensure a reliable connection and prevent sparking in the future.
Connection diagram and installation of a new relay
Installation of a new starting relay is carried out in the reverse order of dismantling. It is critical to correctly orient the unit relative to the compressor. The relay body is usually marked "UP" or an arrow indicating the up position. Incorrect orientation will result in the mechanism not working or closing the contacts in the wrong sequence.
Push the relay onto the compressor pins until it stops. Make sure it fits snugly and doesn't wobble. Then connect the wires to the appropriate terminals according to your diagram or photo. Typically, red or brown wire goes to one pin and white or black to the other, but colors may vary.
Secure the device with a fixing bracket or clamp. Check that the wires do not touch hot compressor tubes or sharp edges of the housing, which could lead to melting of the insulation during operation.
⚠️ Attention: Do not use excessive force when placing the relay on the pins. Compressor fittings are made of copper and are easily broken when subjected to strong bending. If the relay does not fit, check that it is oriented correctly and matches the model.
Once all electrical connections are assembled, reinstall the protective cover and screw the back panel. Make sure that all screws are tightened and the panel does not vibrate when the motor is running.
Checking operation and common errors
After installation is complete, turn on the refrigerator. In the first seconds, you should hear the compressor start confidently without prolonged clicks or humming. The motor should start running smoothly, with a characteristic monotonous sound.
Check the heating of the new relay after 10-15 minutes of operation. It may be warm, but it should not be hot. If the refrigerator began to get cold, and frost appeared in the chamber or the fan started working (in No Frost), it means replacing the start relay it was successful.
A frequent mistake is to ignore the condition of the compressor itself. If the new relay also clicks and does not start the motor, the problem may be deeper: jamming of the piston group or an interturn short circuit. In this case, simply replacing the relay will not help.
It is also important not to mix up the wires when connecting. If you mix up the start and run windings, the compressor may hum but not rotate, which will quickly lead to overheating and combustion. Always double-check the circuit before final assembly.
FAQ: Frequently Asked Questions
Is it possible to start a refrigerator without a starting relay?
Theoretically, you can start the engine manually by briefly applying voltage to the starting winding, but this is extremely dangerous and impractical for constant operation. Without a relay, the compressor will not be able to operate in automatic mode and will quickly burn out from overheating.
Why does a new relay burn out immediately after installation?
This can happen for several reasons: incorrect orientation of the relay, jamming of the compressor, power surges in the network or defective part itself. Also, the cause may be a malfunction of the capacitor (if it is in the circuit) or problems with the wiring.
Where can I find the markings for selecting an analogue?
The markings are usually applied to the side or top edge of the body of the old relay. Look for codes like "RT","P","PCR" and numbers indicating the power or type of compressor. This data will help you choose an exact analogue in a spare parts store.
How long does it take to replace a relay?
For an experienced technician, the process takes 15-20 minutes. For a beginner who is faced with this task for the first time and carefully follows all the steps, including diagnostics and dismantling the panels, the repair may take about 40-60 minutes.