A compressor failure often causes a refrigerator not to work, and in most cases the start relay is to blame. This small element is responsible for starting the engine by supplying the necessary current pulse to the windings. If you notice that the engine hums but won't start, or keeps clicking while trying to start, it's most likely time to replace or reconnect the relay. Understanding how to connect wires to the refrigerator relaycan save your equipment from expensive servicing.
The process of restoring the functionality of the unit requires care and compliance with electrical safety rules, since the work is carried out with an electric current of 220 Volts. Incorrect connection of the contacts can lead to a short circuit, burning of the compressor windings, or even fire of the wiring inside the housing. In this article, we will analyze in detail the design of the trigger mechanism, methods of marking wires and an algorithm of actions that will help you carry out the replacement competently.
Before you begin to physically disconnect any parts, you must completely de-energize the household appliance. Unplug the socket and provide access to the rear wall of the refrigerator where the motor-compressor is located. Only after this can you remove the protective casing and begin diagnosing and replacing the failed element.
Design and principle of operation of the starting relay
The starting relay is an electromechanical switch that controls the supply of voltage to the starting winding of the compressor electric motor. When the refrigerator is turned on, the motor rotor is motionless, and to spin it up, an increased torque is required, which is provided by the starting winding. Electromagnetic relay or a relay with a posistor automatically connects this winding for a few seconds, and then turns it off when the engine picks up operating speed.
There are two main types of devices used in modern and old household appliances: electromagnetic and posistor. Electromagnetic models operate by current passing through a coil, which draws in the core and closes the contacts. The posistor, more modern ones, use the property of the thermistor (posistor) to sharply increase resistance when heated, which actually breaks the starting winding circuit. Understanding your device type is important for proper diagnosis.
⚠️ Note: Visually, relay types may look very similar, but they are not always interchangeable. Using the wrong type of relay may result in the compressor humming but not starting, or the winding burning out.
The relay housing is usually made of durable plastic and has holes for ventilation, since the device can heat up during operation. Inside there are movable and fixed contacts, which, if turned on frequently, can burn or oxidize. It is the contact failure that most often becomes the cause of a malfunction that requires replacing the element with a new one.
Marking of contacts and color coding of wires
The most critical stage of replacement is the correct determination of which wire to connect where. Manufacturers use standard color coding, but you cannot rely on the color of the insulation alone, since the previous technician may have already made changes, or the colors may have faded over time. The main reference point should be markings on the body the relay itself and on the contact group of the compressor.
On the relay body there are usually letters or symbols indicating the purpose of the terminals. The most common designations are L (Line) for the phase wire, N (Neutral) for the neutral wire, as well as the numbers 1, 2, 3 or 4, 5, corresponding to the contacts on the compressor block. There may also be arrow symbols indicating the direction of installation, or designations S (Start) and R (Run).
The color scheme of wires in domestic and imported refrigerators is usually as follows:
- 🔴 Red or brown - phase wire coming from the thermostat or control board.
- 🔵 Blue or white - neutral wire, often connected to the case or coming directly from the plug.
- 🟢 Green or yellow-green - ground wire that is attached to the metal case of the compressor or refrigerator frame.
- ⚫ Black - often used to connect the relay to the contacts compressor inside a plastic casing.
It is important to note that colors may vary depending on the brand. For example, in refrigerators Indesit or Ariston white insulation for the phase is often found, while in Atlant or Biryusa red is traditionally used. Therefore, before disconnecting the old wires, it is strongly recommended to take a photo of the connection diagram or sketch it.
Removing the old relay and preparing for installation
The process of removing a faulty device begins with removing the fixing elements. The relay can be attached to the compressor housing using a metal bracket, spring clips, or simply snap onto the contact pins. Carefully remove the retaining bracket, if there is one, and pull the relay down, slightly rocking it from side to side, to remove it from the contacts.
After removing the relay from the contact group, you need to disconnect the wires. In modern models, the wires are connected through female-male connectors, which are simply removed by hand. In older models, the wires may be soldered or twisted. If you see soldering, use a soldering iron and desoldering pump, being careful not to damage the insulation of adjacent wires. Mechanically biting off the wires is not recommended, as this will complicate the installation of a new element.
Inspect the contact pins on the compressor itself. They must be clean, without traces of soot, oxidation or melting of the plastic. If the contacts are blackened, they must be carefully cleaned with fine sandpaper or a file until they have a metallic shine. Dirty contacts will lead to heating and rapid failure of even a new relay.
Check the new relay to ensure it matches the model. It should sit tightly on the three pins of the compressor and not dangle. Also make sure that the markings on the new device coincide with those on the old one, especially in terms of the position of the contacts (top-bottom).
Wire connection diagram: step-by-step algorithm
Connecting a new relay requires sequential steps. First, make sure the refrigerator is unplugged. Then push the relay onto the contact pins of the compressor until it stops. It should fit tightly, without distortion. You need to navigate by the inscription TOP or the arrow ↑, which should look up.
Next, we proceed to connecting the power wires. The phase wire (usually red or brown) is connected to the terminal marked as L or 1. The neutral wire (blue or white) goes to the terminal N or 2. If your relay does not have explicit markings L and N, refer to the diagram printed on the side wall of the relay case or in the instructions for the refrigerator model.
☑️ Algorithm for connecting the relay
The ground wire (yellow-green) is under no circumstances connected to the relay terminals. It must be securely screwed to the metal housing of the compressor or a special ground terminal on the frame of the refrigerator. Lack of grounding can be life-threatening if the motor insulation breaks down.
For clarity, let's look at the correspondence of contacts using the example of common circuits:
| Designation on the relay | Contact function | Wire color (standard) | Where to connect |
|---|---|---|---|
| L / 1 | Line (Phase) | Red / Brown | From thermostat / board |
| N / 2 | Neutral (Zero) | Blue / White | From plug / mains |
| 3 / 4 / 5 | Compressor contacts | Black (inside the casing) | Internal relay wiring |
| PE / ⏚ | Grounding | Yellow-green | Compressor housing |
After connecting all the wires, check if they are tight. The wires should lie freely, without touching the hot parts of the compressor during operation. Secure the wiring harness with a plastic clamp or clip, if provided by the design.
What to do if the wires are mixed up?
If you connected the phase and zero in reverse, in most cases this is not critical for the operation of the engine, since the alternating current is in the same direction. However, the thermostat and interior lights may stop working or function incorrectly. It is better to stick to color coding.
Typical installation errors and their consequences
One of the most common mistakes is incorrect orientation of the relay on the contacts. Many models of starting devices operate only in a certain spatial position, which is determined by gravity. If you turn the relay upside down, the contacts may not close or, conversely, may not open, which will lead to constant humming of the compressor and its overheating.
Another common mistake is poor contact at the junction of the wires. If you use twisting instead of soldering or special terminals, over time the connection will oxidize and begin to spark and melt the insulation. This may lead to a fire hazard. All connections must be either soldered or made through reliable connectors.
⚠️ Attention: Never leave bare wire ends inside the casing. Even if they do not touch each other, the vibration of a running compressor can bring them together, causing a short circuit. Use insulating tape or heat shrink.
It is also considered a mistake to ignore the condition of the capacitor (if it is in the circuit). When replacing a relay, it is advisable to check the capacitor as well, since its failure may cause the new relay to fail again. A swollen or leaking capacitor requires mandatory replacement.
Diagnostics and performance check after connection
After all the wires are connected and secured, you can proceed to the first test run. Plug in the refrigerator. In the first seconds, you should hear a characteristic click of the relay and the hum of the compressor starting up. If the compressor started working smoothly, without vibrations or extraneous sounds, and after some time cold appeared in the freezer, it means that connection diagram it was assembled correctly.
Pay attention to the behavior of the relay during operation. 1-3 seconds after starting, a second click should be heard - this means the starting winding has turned off. If there is no click, but the compressor hums and heats up, immediately unplug the device. This means that the relay does not open the circuit, and the engine runs on the starting winding, which is detrimental for it.
Check the heating of the relay itself and the wires after 10-15 minutes of operation. They may be warm, but not hot. If you smell burning plastic or see sparking, immediately turn off the power. It is also worth checking the current consumption using current clamps, if possible: it must correspond to the rating indicated on the compressor nameplate.
In some cases, even with correct connection, the refrigerator may not start. This suggests that the problem lies deeper: perhaps the compressor itself is faulty (an interturn short circuit or wedge), the thermostat has burned out, or the electronic control board has failed. In such a situation, simply replacing the relay will not help.
Frequently asked questions (FAQ)
Can I use a relay from another refrigerator?
You can use a relay from another model only if they are completely identical in electrical characteristics, type (posistor/electromagnetic) and seats. Visual similarity does not guarantee compatibility. It is better to select an analogue by catalog number.
Why did the new relay burn out immediately after installation?
There may be several reasons: a short circuit in the compressor windings, a faulty capacitor, incorrect connection of the wires, or a defect in the relay itself. Also, the relay can burn out if the compressor is “jammed” and cannot turn over, consuming a huge starting current.