Connecting the start relay refrigerator: instructions with diagrams and tips

The start relay is a small but critical element of the refrigerator that is responsible for starting the compressor. Without a correctly connected relay, the motor will either not start at all or will work intermittently, which will lead to food spoilage or equipment breakdown. If your refrigerator suddenly stops freezing, makes strange clicks, or does not turn on at all, the problem may lie in this particular unit.

In this article we will look at how to independently connect the start relay to the refrigerator - from preparing tools to testing the operation of the system. You will learn what connection diagrams exist, how to distinguish a faulty relay from a working one, and what mistakes beginners most often make. The instructions are suitable for most models Atlant, Indesit, Samsung, LG and other brands with single-phase compressors. If you have never dealt with electrics, don’t worry: the process is simpler than it seems if you follow a clear algorithm.

What is a starting relay and why is it needed?

A starting relay (sometimes called a start-protective) is an electromechanical or electronic device that performs two key functions:

• 🔌 Starting the compressor: when the refrigerator is turned on, the relay supplies current to the starting winding of the motor, creating the necessary torque to start working.
• 🛡️ Overload protection: if the compressor overheats or a short circuit occurs, the relay opens the circuit, preventing equipment failure.

Without a relay, the compressor will either not be able to start (since the starting winding will not receive power) or will operate in emergency mode, which will lead to its rapid wear. Modern refrigerators use two types of relays:

• 🔧 Electromechanical (with a coil and a core) - reliable, but sensitive to position (must stand strictly vertically).
• 💡 Electronic (based on semiconductors) - compact, less susceptible to wear, but more expensive to replace.

You can determine that the problem is in the relay by characteristic signs:

• 🔊 Refrigerator clicks, but does not start (the relay tries to work, but the circuit does not close).
• ❄️ Compressor buzzes, but does not freeze (the starting winding does not receive current).
• 🔥 Relay heats or smells like burning (short circuit inside the housing).

⚠️ Attention: If the relay is physically damaged (the housing is melted, traces of burning are visible), it must be replaced - repair in such cases is impractical. Also check the integrity of the wires going to the compressor: they often fray or burn out.

Tools and materials for connection

Before starting work, prepare everything you need. Without the right tools, you risk damaging the contacts or connecting the wires incorrectly, which will lead to a short circuit.

You will need:

• 🔧 Screwdrivers (phillips and flathead) - to remove the compressor cover and attach the relay.
• 📏 Multimeter —to check the resistance of the compressor windings and the integrity of the relay circuit.
• 🔌 Soldering iron and solder (optional)—if the wires are oxidized and need cleaning.
• 🧲 Pliers/side cutters —for cutting and stripping wires.
• 📝 Connection diagram (usually glued to the compressor or relay housing).
• 🔒 Insulating tape or heat shrink tube - for insulating connections.

If you are replacing a relay, make sure that the new part matches the parameters:

⚠️ Attention: Never use a relay from another refrigerator model, even if it looks similar. Current and resistance parameters may differ, which will lead to overheating of the compressor.

Preparing the refrigerator for operation: safety and dismantling

Before touching the electrical components of the refrigerator, be sure unplug it and wait until the compressor has cooled down (if it has recently worked). Working with live equipment is deadly!

Next, follow the step-by-step instructions:

1. Move the refrigerator away from the wall to gain access to the back panel. If the model is built-in, it may be necessary to dismantle the decorative box.

2. Remove the compressor protective cover (usually it is secured with 2-4 screws). Under it you will see the compressor itself (a black cylindrical block) and the relay (a small box attached to it).

3. Take a photo of the current connection of the wires - this will help not to confuse them during reassembly. Pay special attention to the colors and location of the terminals.

4. Carefully disconnect the wires from the relay, remembering which one went where. If the contacts are oxidized, clean them with sandpaper or a knife.

If the relay is attached to the compressor with bolts, unscrew them. In some models (for example, Samsung RL-33), the relay can be fixed with latches - in this case, just press them with a screwdriver.

Before installing a new relay, inspect the compressor for damage:

• 🔍 Check if there are any on the compressor housing oil drips - this may indicate a freon leak.
• 🔥 Make sure that the wires are not melted have exposed areas.
• 📏 Measure the resistance of the compressor windings with a multimeter (more on this in the next section).

Checking the compressor and relay before connecting

Before installing a new one relay, you need to make sure that the problem is in it and not in the compressor. To do this, diagnose both elements.

Checking the compressor with a multimeter

The compressor usually has three terminals:

• C (common) - common contact;
• S (start) - starting winding;
• R (run) - working winding.

Measure the resistance between pairs of contacts:

If at least one of the values equal 0 (short circuit) or infinity (break), the compressor is faulty and requires replacement.

Checking the starting relay

To test an electromechanical relay:

1. Apply a voltage of 220 V to the input contacts of the relay (usually they are marked as L and N).

2. Shortly (for 1-2 seconds) close the contacts S and C with a screwdriver - a characteristic sound should be heard, indicating operation core. clicking, meaning the core is triggered.

3. If there is no click, the relay is faulty. Also check the coil resistance with a multimeter - it should be in the range of 10–100 Ohms.

What to do if the relay clicks, but the compressor does not start?

This may indicate two problems: 1) a malfunction of the compressor starting winding (check the resistance C→S); 2) insufficient voltage in the network (check the socket with a voltmeter - it should be at least 200 V).

⚠️ Attention: Do not keep the contacts S and C closed for more than 3 seconds - this can lead to overheating of the compressor windings.

Connection diagrams for the starting relay to the compressor

The connection diagram depends on the type of relay and the model of the refrigerator. On most devices it is indicated on a sticker next to the compressor or on the relay housing. If there is no sticker, use the standard options.

Standard circuit for a 3-pin relay

Suitable for most refrigerators Atlant, Biryusa, Nord:

L (phase) ────┬─────┬───── Relay ───── C (compressor)
│     │
N (zero) ────┴ └───── R (working winding)
S (starting winding)

Connection order:

1. To the contact L on the relay, connect the phase wire (usually brown or red).

2. To the contact N —neutral wire (blue or black).

3. To the contact C on the compressor, connect the common wire from the relay.

4. To S and R —starting and operating windings, respectively.

Scheme for a 4-pin relay (with additional protection)

Used in models Samsung, LG, Beko:

L ────┬─────┬───── Relay ───── C
│     │
N ────┴     ├───── R
│
Protection ────┘

Difference from the 3-pin: the fourth wire goes to thermal protection (usually yellow or green). It is connected to the corresponding contact on the relay (can be marked as T or PTC).

If you are not sure about the circuit, use the universal rule:

• 🔌 Phase and zero always go to the relay input (contacts L and N).
• 🔄 Common wire from the relay go to contact C compressor.
• 🔄 Starting and operating windings connect to S i R respectively.

Step-by-step instructions for connecting the relay

Now let's move on to the practical part. Follow the instructions carefully - errors at this stage can lead to a short circuit or failure of the compressor.

1. Install the relay on the compressor. If it is secured with bolts, tighten them moderately - do not pinch them so as not to damage the housing. In models with latches, just press until they click.

2. Connect the wires according to the diagram. Start with the phase and zero (they come from the power cord) then connect the common wire to the compressor, and then the starting and working windings.

3. Check the reliability of the contacts. All wires should fit tightly, without play. If the terminals are loose, tighten them with pliers.

4. Insulate the exposed areas. Do not use electrical tape or heat-shrink tubing. leave exposed wires!

5. Reinstall the compressor protective cover. Make sure that it does not touch the wires and does not interfere with the operation of the fan (if there is one).

Before the first switching on:

• 🔌 Check that the refrigerator is disconnected from the network.
• 📏 Check the connection diagram again.
• 🔍 Make sure that no foreign objects are touching the compressor or relay.

Now you can turn on the refrigerator. If everything is connected correctly:

• 🔊 You will hear one click (relay operation) and the hum of the compressor.
• ❄️ After 5-10 minutes, the freezer will begin to cool.

⚠️ Attention: If, after turning on, the relay clicks repeatedly in a row and the compressor does not start, immediately disconnect the refrigerator from the network. This is a sign of a malfunction of the compressor or incorrect connection of the windings.

Typical errors and how to avoid them

Even experienced craftsmen sometimes make mistakes when connecting the start relay. Here are the most common ones and ways to prevent them:

Error	Consequences	How to avoid
Confused windings S i R	The compressor hums, but does not start	Check the resistance: the starting winding (C→S) always has greater resistance than the working one (C→R)
Weak contact in terminals	The relay gets hot, the compressor works intermittently	Tighten the terminals with pliers, check the reliability of the connections
Incorrect position of the electromechanical relay	The relay does not work or clicks chaotic	Install the relay strictly vertically (the arrow on the body should look up)
Using a relay with inappropriate parameters	Overheating of the compressor, failure	Check the rated current and resistance of the windings before purchase

A few more nuances that are often forgotten:

• 🔌 The polarity of connecting phase and zero does not matter for the operation of the relay, but some models of refrigerators (for example, Liebert) may require strict adherence to polarity.
• 🔧 Oxidized contacts - if on the compressor terminals or the relay has a green coating, clean them with sandpaper or a special contact liquid.
• 📏 Wire length —do not shorten them unnecessarily. If the wires are too short, use terminal blocks to extend them.

If, after replacing the relay, the refrigerator works, but after a few days it refuses to turn on again, the problem may lie in an unstable network voltage. Install a voltage stabilizer - this will extend the life of the compressor.

What to do if, after connecting the relay, the refrigerator does not work

If you have completed all the steps, but the refrigerator does not start, do not panic. Systematically check the possible ones. reasons:

1. Check the power. Make sure there is voltage in the outlet (try connecting another device). If the voltage is below 200 V, the compressor may not start.

2. Ring the relay. Even if it is new, it may be defective. Check the coil resistance and integrity of the contacts.

3. Diagnose the compressor. If it hums but does not start, the piston may be jammed. Try manually turning the compressor shaft (this cannot be done through a relay - only with a direct connection).

4. Check the thermostat. If it is is faulty, the compressor will not receive a signal to start. Disconnect the wires from the thermostat and short them together - if the compressor starts, the problem is in the thermostat.

If all checks did not produce results, the problem may be:

• 🔌 Electronic control unit (in models with display).
• 🧊 Freon leak —the compressor will try to start, but will immediately turn off due to high pressure.
• 🔋 Malfunctions of the starting capacitor (if it is in the circuit).

In such cases, it is better to contact a specialist, since repairs will require special equipment (for example, a freon charging station).

FAQ: Frequently asked questions about connecting the start relay

Is it possible to connect a relay from another refrigerator model?

Theoretically, it is possible, but only if they match rated current, relay type (electromechanical/electronic) and connection diagram. For example, a relay from Atlant may be suitable for Biryusaif they have the same compressors. However, it is better to use an original part or an analogue with the same parameters.

How to check if the relay works without a compressor?

Connect the relay to a 220 V network (phase and zero to the input contacts). Then briefly close the contacts S i C —you should hear a click. If it is missing, the relay is faulty. Do not keep the contacts closed for more than 2-3 seconds!

What will happen if you mix up the starting and operating windings?

The compressor will not start, but will hum. In this case, it is enough to change the wires S and R places. Long-term work with reversed windings can lead to overheating of the compressor.

Is it necessary to discharge the capacitor before operation?

Yes, if your refrigerator model has one starting capacitor (usually cylindrical). Before disconnecting the wires, short-circuit its terminals with a screwdriver with an insulated handle to avoid electric shock.

Can the relay be repaired or just replaced?

Electromechanical relays can sometimes be repaired (cleaning the contacts, replacing the spring), but in most cases it is easier and more reliable to replace it with a new one. Electronic relays cannot be repaired - only replacement.