Connecting the refrigerator start relay: diagrams, errors and step-by-step instructions

The starting relay is a small but critical element of the refrigerator, which is responsible for starting the compressor. Without a properly connected relay, the motor will either not start or will work intermittently, which will lead to food spoilage or equipment breakdown. Many owners are faced with the need to replace or reconnect a relay after a renovation, move, or malfunction. However, even experienced craftsmen sometimes confuse contacts or choose an incompatible model.

In this article we will analyze all types of starting relays (induction, posistor, electronic), give detailed connection diagrams for popular compressors Danfoss, Embraco, Secop and other brands, and also show how to avoid common mistakes. You will learn what tools you will need, how to check the functionality of the relay before installation and what to do if after connecting the refrigerator does not turn on.

⚠️ Important: Working with the electrical components of the refrigerator requires compliance with safety precautions. If you are not confident in your skills, it is better to contact a professional - incorrect connection can lead to a short circuit or failure of the compressor.

Types of starting relays: which one is in your refrigerator?

Before connecting the relay, you need to determine its type. The connection diagram, compatibility with the compressor, and even the method for diagnosing faults depend on this. There are three main types:

• 🔄 Induction (tablets) —the most common in older refrigerator models (Atlant, Biryusa, Stinol). They have a round shape and a characteristic “tablet” body.
• 🔥 Posistor (RTS) - modern relays with a thermistor, which heats up when current passes. Used in compressors Embraco, LG, Samsung.
• 📱 Electronic - fully controlled by microcircuits, often found in inverter refrigerators (Mitsubishi Electric, Panasonic).

As a rule, the type of relay is indicated on its body. For example, the inscription PTC or Posistor speaks of a posistor type, and the designation RLS or RLM speaks of an induction type. If there is no marking, focus on the form:

⚠️ Attention: Some refrigerators (for example, Liebert or Thermoking) use combined relays with additional functions (overheat protection, current control). Such devices cannot be replaced with standard ones - an exact match to the model is required.

Tools and preparation: what you will need for work

To connect the starting relay, you do not need complex devices, but you cannot do without a minimum set of tools:

• ⚡ Multimeter - to check the resistance of the compressor windings and the integrity of the relay contacts.
• 🔧 Screwdrivers (cross and flat) - for dismantling the compressor protective casing.
• 🔌 Pliers or pliers - for careful removal and installation of terminals.
• 📏 Marker or sticker —to mark the wires before disconnecting (avoid confusion!).
• 🧤 Dielectric gloves —to protect against electric shock (especially if the refrigerator is not disconnected from the network).

Also prepare your workplace:

1. Unplug the refrigerator and wait until the compressor cools down (at least 30 minutes).
2. Move the equipment away from the wall to gain access to the back panel.
3. Take a photo of the current connection of the relay - this will help avoid mistakes during reassembly.

⚠️ Attention: If your refrigerator is equipped with inverter compressor (for example, Samsung Digital Inverter or LG Linear Compressor), never connect a regular starting relay to it. Inverter models require specialized electronic control units, and replacing with a mechanical relay will lead to breakdown!

Connection diagrams: step-by-step instructions for different types relay

The connection diagram depends on the type of relay and the compressor model. Below we will discuss the three most common options. Carefully check the markings on your relay and compressor!

1. data-i="132">This is the simplest relay with two contacts: Danfoss, Secop)

This is the simplest relay with two contacts: S (Start) and M (Main - working). It is connected in parallel with the starting winding of the compressor. Procedure:

Remove the protective casing from the compressor|Mark the wires going to it. relay (usually red - start, black - working)|Disconnect the old relay|Connect the new relay to the contacts S i M on the compressor|Attach the relay to the compressor housing (often there is a special holder)|Check the reliability of the contacts|Install the casing in place-->

Connection diagram:

Compressor
┌───────────┐
│ C (Common) │
│ S (Start) │───┬───[Relay]───┐
│ M (Working)│───┘ │
└───────────┘                 │
┌─┴─┐
│220V│
└───┘

2. compressors Embraco, LG)

Three contacts: C (General), S (Start), R (Working). The posistor (thermistor) heats up and opens the circuit after the compressor starts. wires!

Typical error: connecting the wire from S to R and vice versa. This leads to the compressor humming, but not starting. Correct diagram:

Compressor Relay
┌───────────┐    ┌───────┐
│ C (General) │───┤ C │
│ S (Start) │───┤ S │
│ R (Working)│───┤ R │
└───────────┘    └───────┘

How to distinguish the contacts on the compressor Embraco?

On the compressor body there is usually a tag with the following designations:

- C — common contact (often black wire).

- S — starting winding (red or white wire).

- R — working winding (brown or blue wire).

If there is no tag, use a multimeter: the resistance between C-S should be higher than between C-R (usually 20–30 Ohm vs 10–15 Ohm).

3. Electronic relay (for inverter refrigerators)

Here everything is more complicated: the relay is often integrated into the control board and connected via a connector. Self-replacement requires an exact match to the model. For example, for Samsung DA97-08006A the diagram will be like this:

Control board
┌───────────────┐
│ CN1 (Connector) │───┐
└───────────────┘   │
│
┌───────────────┐   │
│ Compressor │←──┘
└───────────────┘

⚠️ Attention: In inverter refrigerators (Panasonic NR-B, Hitachi R-W), an electronic relay is often combined with a power supply. Replacing only the relay without calibrating the board may result in an error E1 or E4 on the display.

Checking the relay before connecting: how to avoid defects

The new relay may turn out to be faulty (especially if bought at the market or secondhand). Before installation, be sure to check its functionality. Here's how to do it:

1. External inspection

• 🔍 Check the housing for cracks, melting or traces of burning.
• 🧲 Make sure that the contacts are not oxidized or bent.
• 📄 Check the markings with the original relay (the model and nominal current).

2. Testing with a multimeter

For inductive and posistor relays:

1. Set the multimeter in resistance test mode (200 Ohms).
2. Measure the resistance between the contacts S and M (for induction) or S-C i R-C (for posistor).
3. Normal values:
   • Induction: 10–50 Ohms between S-M.
   • Posistor: 20–40 Ohms between S-C, 10–20 Ohms between R-C.

If the resistance is equal to 0 (short circuit) or ∞ (open), relay faulty.

3. Checking for a spark

For experienced users: you can briefly apply voltage to the relay (through a 40 W light bulb for safety) and check whether the mechanism works. But this method is dangerous - use only if you are confident in your skills!

Typical errors when connecting and how to avoid them

Even experienced technicians sometimes make mistakes that lead to compressor breakdown or repeated repairs. Here are the most common mistakes:

• 🔌 Mixed up wires —especially true for posistor relays. If you swap S and R, the compressor will hum, but will not start.
• 🔧 Weak contact —poorly secured terminals lead to heating and melting of the wires.
• 🔥 Ignoring the rated current —a 5 A relay will not withstand a 10 A compressor load.
• 📉 Lack of grounding —in some models, the relay is attached to the compressor housing, providing grounding. If you forget to secure it, current leaks are possible.
• ⚡ Working under voltage - even if the refrigerator is unplugged from the outlet, capacitors can retain charge!

How to avoid problems:

1. Always mark the wires before disconnecting (use colored stickers or a marker).
2. Check that the terminals are securely fastened - they should not be loose.
3. Check the compressor data sheet: the maximum relay current is indicated there.
4. After connection, run the refrigerator idle (without food) for 1-2 hours to check the stability of operation.

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

You connected the relay, but the refrigerator does not turn on or does not work correctly? Let's look at possible causes and solutions:

If all checks have failed, the problem may not be in the relay, and in:

• 🔋 Thermostat — if it does not give a start signal.
• 🔌 Starting capacitor —if the capacity is below normal.
• 🔄 Compressor windings —if there is interturn short circuit.

Critical information: If the compressor starts to heat up after several starting attempts, but does not rotate, immediately turn off the refrigerator! Long-term operation in this mode will lead to jamming of the motor and the need to completely replace the compressor.

Replacing relays in refrigerators of popular brands: nuances

Each manufacturer has its own design and connection features of the relay. Let's consider the most common brands:

1. Atlant and Biryusa

Most models use an inductive relay RTK-X or DHR. Features:

• The relay is attached directly to the compressor housing using a clamp.
• The wires are often marked: red - start, black - working, yellow-green - grounding.
• When replacing, be sure to check the resistance of the compressor windings (norm: C-S = 20–30 Ohms, C-M = 10–15 Ohms).

2. Samsung and LG (with inverter compressors)

Electronic relays integrated into the control board are used. Replacement requires:

• Exact matching of the relay model (for example, DA97-08006A for Samsung).
• Resetting errors through the service menu (the combination of buttons depends on the model).
• Checking the voltage on the board (there should be 12-14 V on the control Contacts). A.

3. Embraco (compressors in Indesit, Ariston)

Most often, posistor relays are installed 3TS or PTC. Important:

• The posistor must be designed for a current of at least 1.5–2 A.
• Contact S and R on the compressor are often marked with dots or letters.
• After replacing the relay, check the pressure in the system (if the freon level is low, the compressor will overheat).

How to reset the error on Samsung after replacing the relay?

For models with a display:

1. Unplug the refrigerator for 1 minute.

2. Turn on and immediately press Power Cool + Fridge for 5 seconds.

3. Wait for the sound signal (the error will be reset).

For models without a display: turn off the power for 10 minutes, then turn it on again.

FAQ: Frequently asked questions about starting relays

Is it possible to replace the induction relay with posistor?

Theoretically, yes, but only if the compressor supports this type of start. For example, many models Danfoss are compatible with both types of relays. However, you need to:

1. Select a posistor with a suitable resistance (usually 15–30 Ohms).
2. Connect the contacts correctly (C, S, R).
3. Make sure that the rated current of the relay is not lower than that of the original one.

In inverter refrigerators, replacing a mechanical relay with an electronic one and vice versa is unacceptable.

How check if the relay or compressor has burned out?

First, disconnect the relay from the compressor and check the resistance of the compressor windings:

• If between C-S and C-R the resistance is normal (not 0 and not ∞), and the relay does not click when voltage is applied - the problem is in the relay.
• If the windings show an open or short circuit, the compressor is faulty.

Also pay attention to the burning smell: if it comes from the relay, it needs to be replaced. If the smell is from the compressor, the windings are most likely burned out.

What happens if you connect a relay without grounding?

In most cases, the refrigerator will work, but:

• The risk of electric shock when touching the body increases.
• The likelihood of relay malfunctions due to interference increases.
• In some models (for example, Liebert), the lack of grounding can lead to false tripping of the protection.

If your outlet does not have a ground, use an RCD (residual current device).

Where to buy an original relay for a refrigerator?

It is better to buy original relays:

• At the manufacturer's service centers (for example, for Samsung or LG).
• At official spare parts dealers (for example, Embraco or Danfoss).
• On proven sites (for example, AliExpress - but only from sellers with a rating above 98%).

Cost of the original relay: from 500 to 3000 rubles depending on the type. Analogs (for example, Startcap) may cost less, but their reliability is lower.

Is it possible to repair a burnt-out relay?

Inductive and posistor relays cannot be repaired —they can only be replaced. Electronic relays in rare cases can be repaired. (replacing capacitors or transistors on the board), but this requires specialized skills and equipment.

If the relay burns out due to a voltage surge, before installing a new one, check:

• The stability of the voltage in the network (should be 220–230 B).
• Operation of a surge protector or stabilizer.
• Integrity of the refrigerator wiring (are there any melted areas).