How to connect the refrigerator relay to the wires: step-by-step instructions with photos and diagrams

When the refrigerator suddenly stops freezing, but the light inside is on and the compressor does not start - in 70% of cases it is to blame start-up protection relay. This small unit is responsible for starting the motor and protecting against overheating, and its malfunction is often solved by a simple replacement. However, many are faced with a problem: how to properly connect a new relay to the wires so as not to burn the compressor or cause a short circuit?

In this article we will analyze three types of relays (induction, posistor and electronic), we will show connection diagrams for popular refrigerator models (Atlant, Indesit, Samsung, Biryusa), and we will give step-by-step instructions with photos. You will learn what tools you will need, how to test the wires with a multimeter, and why you should never connect a relay without checking the resistance of the compressor windings.

If you are not confident in your abilities, it is better to contact a specialist. But if you’re ready to figure it out on your own, read on: we’ve minimized theory and focused on practice.

1. Types of relays in refrigerators: which one do you have?

Before you take up the soldering iron, you need to determine which relay is installed in your refrigerator. The connection diagram and even the set of tools depend on this. There are three main types:

  • 🔄 Induction (electromechanical) - an outdated type, but still found in refrigerators ZIL, Minsk and Soviet models. It works on the principle of a coil with a core and produces a characteristic click when triggered.
  • 🔥 Posistor (thermistor) — modern relays with a semiconductor element that heats up and opens the circuit when overload. Installed in 80% of household refrigerators (Atlant, Indesit, LG).
  • 📱 Electronic - used in inverter compressors (Samsung No Frost, Liebert). They are controlled by a microcircuit, often built into the control board.

How to determine the type of your relay?

  1. Unplug the refrigerator and remove the back cover (or panel covering the compressor).
  2. Find a black or gray plastic box attached to the compressor - this is it relay.
  3. If there is a metal plate with a spring on the body, it is a inductive. data-i="77">positor relay. If a round ceramic disk is visible, it is posistor. If the relay is soldered to a board with microcircuits, it is electronic.
⚠️ Attention: In refrigerators with a system No Frost there may be two relays: one for the compressor, the second for the fan. Do not confuse them - the connection diagram is different!
📊 What relay is installed in your refrigerator?
Induction (old model)
Posistor (modern)
Electronic (inverter compressor)
I don’t know, not yet looked

2. Tools and materials: what you need for work

To connect the relay to the wires, you do not need expensive tools. Here is the minimum set:

Tool/material What is needed Is it possible replace
Multimeter (tester) Testing the wires, checking the resistance of the compressor windings No (required!)
Phillips/flat screwdriver Removing the relay cover, fastening contacts Yes (any will do)
Soldering iron (25–40 W) + solder Soldering wires to relay contacts Partially (terminals can be used)
Insulating tape or heat-shrink tube Insulation of connections Yes (cambrics can be used)
New relay (analogue of the old one) Replacement of a faulty unit No (must be the same in type and parameters)

If you buy a new relay, be sure to check its compatibility with your compressor. The following are usually indicated on the body of the old relay:

  • 🔢 Rated current (for example, 5A or 10A).
  • 🔌 Mounting type (clip, screws, soldering).
  • 📏 Dimensions (must match the seat).
⚠️ Attention: Refrigerator relay Indesit is not suitable for Atlant even if they are similar in appearance! The difference in current characteristics can lead to overheating of the windings.

3. Connection diagram of the relay to the compressor: disassemble the wires

Before disconnecting the old relay, take a photo of its connection or draw a diagram. This will save you from mistakes during reassembly. A typical connection diagram looks like this:

There are three wires coming to the compressor three wires:

  1. Common (C) - coming from the plug. refrigerator.
  2. Start winding (Start, S) — briefly supplies current to start the motor.
  3. Working winding (Run, R) —main power circuit.

On the relay, these contacts are indicated by letters or colors. For example:

  • 🔴 Red wire — common (C).
  • 🔵 Blue wire — working winding (R).
  • ⚪ White/yellow wire —starting winding (S).

But colors may differ! Therefore, always check the purpose of the wires with a multimeter:

  1. Set the multimeter to resistance measurement mode (200 Ω).
  2. Measure the resistance between C and R - there should be 10–40 Ω (working winding).
  3. Measure the resistance between C and S —should be 20–60 Ω (start winding).
  4. The resistance between R and S should be equal to the sum of the two previous values (this is an integrity check windings).
What to do if the resistance of the windings does not meet the standard?

If the resistance between C-R or C-S equals 0 Ω (short circuit) or ∞ (break), the compressor is faulty and requires replacement. In this case, there is no point in connecting the relay - the engine will not start.

4. Step-by-step instructions: how to connect the relay to the wires

Now let's move on to practice. Follow this algorithm, and you will avoid mistakes:

Disconnect the refrigerator from the network and wait for the capacitor to discharge (5-10 minutes)|

Take a photo or sketch the current connection diagram|

Ring the compressor windings with a multimeter|

Prepare a new relay and tools -->

Step 1. Removing the old relay

Carefully disconnect the wires from the relay terminals (you can pry them off with a screwdriver if the contacts are stuck). If the relay is screwed to the compressor, unscrew the fastening screws. latches - press them with a screwdriver.Samsung) the relay is attached to latches - press them with a screwdriver.

Step 2. Preparing the wires

Strip the ends of the wires 5–7 mm (use a knife or stripper). If the wires are oxidized, treat them with alcohol or sandpaper. Do not use acid!

Step 3. Connecting a new relay

Check the diagram or photograph of the old connection. Connect the wires to the terminals of the new relay in this order:

  1. Common wire (C) - to the terminal Common or L.
  2. Working winding (R) - to terminal Run or M.
  3. Start winding (S) - to the terminal Start or S.

Step 4. Soldering or crimping contacts

If the relay terminals are designed for soldering:

  • 🔥 Heat the soldering iron and tin the wires (cover with a thin layer of solder).
  • 🔧 Solder the wires to the terminals, avoiding overheating (do not hold the soldering iron longer 3-5 seconds).
  • 🛡️ Insulate the connections with heat-shrink tubing or electrical tape.

If the terminals are screw-type, just tighten the wires with a screwdriver, but do not overdo it, so as not to crush the wires.

Step 5. Check before starting

Before turning on the refrigerator:

  • 🔍 Visually check for exposed wire sections.
  • 📊 Test the circuit again with a multimeter (resistance between C-R and C-S should remain the same).
  • 🔌 Make sure that the relay sits tightly on the compressor (without backlash).

5. Common mistakes and how to avoid them

Even experienced craftsmen sometimes make mistakes when connecting the relay. Here are TOP-5 mistakes and their consequences:

Error What will happen How to avoid
The wires are mixed up S and R The compressor will not start or will work with overheating Ring the windings with a multimeter before connecting
Weak contact at the terminals Sparking, plastic melting, relay failure Soldering or reliable crimping of the terminals
Using a relay with a lower rated current The relay will overheat and burn out after 1-2 days of operation Check the markings on the relay body
Lack of insulation on the connections Short short circuit when touching the housing Use heat shrink or electrical tape
Connection without checking the compressor The new relay will burn out if the compressor is broken Always ring the windings before replacement

Especially often errors occur when working with inverter compressors (Samsung Digital Inverter, LG Linear). In them, the relay is often built into the control board, and replacing it requires soldering SMD components. If you are not confident in your skills, it is better to take the board to the service.

⚠️ Attention: In refrigerators No Frost with electronic control (for example, Bosch KGE39XW2ARafter replacing the relay, you may need to reset errors through the service menu. Without this, the compressor will not start!

6. Checking operation after connection

You have connected the relay, but how do you know that everything was done correctly? Follow this checklist:

  1. Plug in the refrigerator. You should hear a relay click (in induction models) or a quiet hum (in posistor models).
  2. Listen to the compressor. After 1–3 seconds after the click the motor should start. If you hear any extraneous sounds (knocking, grinding), turn off the refrigerator immediately!
  3. Check the temperature. After 15–20 minutes the rear grille (condenser) should heat up. If it is cold, the compressor does not work.
  4. Use the tester. When the compressor is running, the voltage between C-R should be 220V, between C-S — 0V (after startup).

If the compressor starts, but after 5-10 seconds turns off, two problems are possible:

  • 🔋 The starting capacitor is faulty (needs to be replaced).
  • 🔥 Overcurrent (check the relay for compliance with the rating).

Manufacturers often use unique connection diagrams. Let's consider the nuances for the most common brands:

Atlant i Biryusa (posistor relays)

In these refrigerators, the relay is attached to the compressor using spring clip. The main feature is starting winding (S) connected via external capacitor (black cylinder next to the relay). When replacing the relay, be sure to check the capacitor with a multimeter (the resistance should drop from ∞ to 0 Ω).

Indesit i Ariston (relay RBM-10)

Here the relay is often combined with thermal fuse. If the refrigerator turns off after 10–15 minutes work, the problem may be in the fuse (check for an open circuit). When replacing the relay use only the original (RBM-10 or RBM-15) - analogues may not work.

Samsung (inverter models)

In inverter refrigerators (Samsung RB37J5230), the relay is built into the inverter board. Replacement requires:

  1. Disconnecting the board from the compressor.
  2. Soldering a new relay (use flux for SMD).
  3. Checking signals from the control board (should be 5V on the control contact).

Without experience with electronics, it is better to contact the service.

LG (system Linear Compressor)

In models with a linear compressor (LG GA-B489YDQZ) the relay is missing as a separate element - its functions are performed by control module. If the compressor does not start, diagnostics of the board is required (the error code is displayed on the display).

⚠️ Attention: In refrigerators Liebert and Electrolux with electronic control, after replacing the relay it may be necessary reflashing the board. Without this, the compressor will be blocked by the protection system.

FAQ: Frequently asked questions about connecting a relay

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

Only if they match:

  • Type of relay (induction/posistor/electronic).
  • Rated current (indicated on the body).
  • Connection diagram (number and location of terminals).

For example, a relay from Atlant can be installed on Biryusuif the compressor models are identical (Danfoss NL8F). But the relay from Indesit is not suitable for Samsung - different current characteristics.

What to do if after replacing the relay the compressor hums, but not starts?

The reasons may be:

  1. Faulty Starting capacitor (call it).
  2. The compressor is jammed (try turning the shaft manually - if not rotates, replacement is needed).
  3. Low voltage in the network (should be 200–240V).
  4. Wires are incorrectly connected S and R (swap them).

If the compressor is humming and heats up - turn it off urgently, otherwise the winding will burn out!

How to test a relay without a multimeter?

Method for induction relays:

  1. Disconnect refrigerator from the network.
  2. Remove the relay and shake it - if you hear a knock (loose core), the relay is faulty.
  3. Connect the relay to the network 220V through the light bulb (in series). If the light bulb lights up and goes out when heated, the relay is connected. working.

⚠️ Danger! This method requires experience in working with electricity. It is not suitable for posistor relays.

How much does it cost to replace a relay in the service?

The cost depends on the type of relay and the model of the refrigerator:

  • Replacement of a posistor relay: 1500–2500 ₽ (with work).
  • Replacement of an induction relay: 1000–2000 ₽.
  • Repair of a board with an electronic relay: 3000–6000 ₽.

Prices are valid for Moscow and regions for 2026 Refrigerator services often offer a discount on diagnostics.

Is it possible to repair a relay instead of replacing it?

Induction relays can sometimes be repaired:

  • If the contacts are oxidized, clean them with sandpaper.
  • If if the case is cracked, seal it with epoxy resin.
  • If the coil is burned out, rewind it (you need a thin copper wire).

Posistor and electronic relays not repaired -replacement only. Attempts to repair them can lead to a fire hazard.

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