Checking the refrigerator start relay with a multimeter: step-by-step guide with photos and diagrams

When the refrigerator suddenly stops freezing, but the light inside is on, and the compressor does not start or turns off after a few seconds - the culprit in 60% of cases turns out to be starting relay. This small unit is responsible for starting the motor-compressor, and its failure leads to typical symptoms: humming without cooling, an on-off cycle, or complete silence. You can check the relay yourself using multimeter - this will save up to 3,000 rubles on diagnostics at a service center.

In this article you will find unique connection diagrams for different types of relays (RTP-1, DHR, RSI, etc.), normal resistance values for popular refrigerator models (Atlant, Indesit, Samsung, Liebherr), as well as step-by-step instructions with photos on how to avoid common mistakes when checking. If you have never held a multimeter in your hands, don’t worry: we will even figure out how to correctly connect the probes and decipher the device readings.

What is a starting relay and how does it work

The starting relay is electromechanical or electronic devicewhich briefly connects starting winding the compressor at the time of startup. Without it, the motor simply will not be able to start rotating due to the high starting current (5–7 times higher than the rated current). The relay is activated for a split second, and then turns off the starting winding, leaving only the working one to work.

In refrigerators, three types of relays are used:

• 🔹 Tablet (RTP-1, RTK-X) - the most common in models Biryusa, Atlant, Stinol. It has a round housing and is connected directly to the compressor.
• 🔹 DHR (davikovoe) —installed on refrigerators Indesit, Ariston. Recognized by its rectangular shape and the presence of a coil.
• 🔹 Electronic (RSI, PTC) - modern models Samsung, LG, Liebherr. Often integrated into the control board.

The principle of operation is the same for all types: when voltage is applied to the compressor, the relay closes the contacts of the starting winding, and after acceleration of the motor (after 1-3 seconds) it opens them. If the relay “sticks” or does not work, the compressor either will not start or will burn out from overheating.

Signs of a faulty starting relay

Before you take the multimeter, make sure that the problem is in the relay. Typical symptoms:

• 🔊 The compressor hums, but does not start —the sound of a running engine is heard, but there is no cold. This means that the starting winding is not connected.
• ⚡ Short operating cycles —the compressor turns on for 1-5 seconds and turns off. The relay may “release” the contacts too early.
• 🔥 Compressor overheating —the motor body is hot, but the refrigerator does not freeze. Perhaps the relay does not open the starting winding, and it overheats.
• 🚫 Complete silence —there are no sounds when turned on. There may be a break in the relay coil or contacts.

The same symptoms occur when there is a malfunction of thermostat, starting capacitor or the compressor itself. To exclude the relay, you need diagnostics with a multimeter.

⚠️ Attention: If the compressor turns on and immediately turns off with a loud click, this may be a sign interturn short circuit in the motor windings, not a breakdown relay In this case, check the resistance of the compressor windings before by testing the relay.

Preparation for testing: tools and safety measures

For diagnostics you will need:

• 🔧 Multimeter (digital or pointer) with modes for checking resistance (Ω) and voltage (V).
• 🔌 Screwdriver cross/flat - for dismantling the relay.
• 📸 Smartphone - to photograph the connection diagram to disconnecting wires.
• 🧤 Insulating gloves (optional) - for protection against accidental electric shock.

The procedure for turning off the refrigerator:

1. Unplug the plug from the socket.
2. Wait for complete defrosting (if the refrigerator was turned on).
3. Move the refrigerator from the wall to get access to the compressor.

⚠️ Attention: Do not check the relay without disconnecting it from the compressor! Voltage in the circuit may damage the multimeter or cause a short circuit. Always remove the terminals before beginning measurements.

Disconnected the refrigerator from the network|Took a photo of the connection diagram|Prepared the multimeter (battery checked)|Wearing protective gloves (optional)|Disconnected the relay from the compressor -->

Step-by-step instructions: how to check the starting relay with a multimeter

The testing algorithm depends on the type of relay. Below is a universal technique suitable for 90% of models.

1. Removing the relay

The relay is attached to the compressor housing (usually on the right or top). Carefully disconnect it, remembering or photographing the location of the wires. There may be marks on the relay body:

• S (Start) - starting winding,
• R (Run) - working winding,
• C (Common) - common contact.

2. Checking the coil resistance (for electromechanical relays)

Switch the multimeter to resistance measurement mode (Ω, range 200 Ohms). Connect the probes to the coil terminals (usually these are two contacts on the relay body, not connected to the compressor terminals).

3. Checking the relay contacts

Switch the multimeter to the “continuity” mode (diode icon or buzzer). Connect the probes to the contacts S i C (start winding). In normal condition, the contacts should be open (resistance = ∞). If the device shows 0 Ohm - the contacts are “stuck”, the relay must be replaced.

To check operation:

1. Connect the relay to the compressor (without connecting the power!).
2. Apply 220V voltage to the coil contacts (via an extension cord with a switch).
3. At the moment the voltage is applied, the contacts S–C should close (resistance = 0 Ohm), and after 1-2 seconds, open.

4. Diagnostics of the starting capacitor (if any)

In some models (for example, Samsung RL-33), the relay is integrated with the capacitor. To check the capacitor:

1. Disconnect it from the circuit.
2. Set the multimeter to capacitance measurement mode (F).
3. Connect the probes to the terminals of the capacitor. The normal value is ±20% of that indicated on the case (for example, for 25 μF 20–30 μF is acceptable).

What to do if the multimeter shows “OL” when checking the contacts?

This means that the resistance between the contacts tends to infinity (open circuit). For normally open contacts (eg S-C in the off state) this is normal. But if “OL” appears where there should be a non-zero resistance (for example, on a coil), this is a sign of a break.

Decoding the results: when the relay is working and when it is not

Compare the received data with standard values:

If the relay is working, but the compressor does not start, check:

• 🔌 Power —voltage in the socket (should be 220–230V).
• 🌡️ Thermoregulator —ring its contacts (in the “max” position the resistance should be 0 Ohm).
• 🔄 Compressor —measure the resistance of the windings (norm for R: 15–40 Ohm, for S: 20–50 Ohm, for R+S: the sum of R and S).

Typical errors when checking relays and how to avoid them

Even experienced craftsmen sometimes make mistakes that lead to incorrect diagnostics:

• ❌ Test under voltage — never ring the relay without disconnecting it from the network! This may damage the multimeter or cause a short circuit.
• ❌ Ignoring temperature —if the compressor is hot, the relay may not operate. Let the refrigerator cool for 1-2 hours.
• ❌ Confusion with contacts —always check the diagram before checking! For example, in a relay DHR contacts may be marked differently than in RTP-1.
• ❌ Checking an electronic relay as an electromechanical one —in an RSI relay there are no physical contacts for calls. They are diagnosed only by the output voltage.

Another common mistake is failure to check the compressor. If the relay is working properly, but the engine does not start, the compressor itself may be to blame (broken winding, jammed piston). Always check the resistance of the compressor windings after relay testing!

⚠️ Attention: In refrigerators with a system No Frost (for example, Samsung RL-34) the relay can be integrated into the control board. Checking it requires special equipment (oscilloscope), and it is impossible to diagnose such a relay at home. In this case, contact the service.

How to choose a new relay: compatibility and analogues

If the relay is faulty, it must be replaced. The main rule is the new relay must be fully compatible by:

• 🔌 type - tablet (RTP-1), DHR or electronic (RSI).
• 📏 Dimensions - the housing must be suitable to the mount on the compressor.
• ⚡ Rated current —indicated on the housing (for example, 5A, 10A).
• 🔄 Connection diagram —number and location of contacts.

The table below contains analogues of popular relays:

When purchasing, pay attention to compressor marking (for example, Embraco EGX 90HLC or Secop Danfoss NL6L). Some relays are only suitable for specific compressor models!

FAQ: Frequently asked questions about checking the starting relay

Is it possible to check the relay without a multimeter?

Yes, but with limitations. Disconnect the relay from the compressor and supply it with 220V through an extension cord with a button. When voltage is applied, a click should be heard (contact activation). However, this method will not show a broken coil or worn contacts - only a gross mechanical failure.

The relay clicks, but the compressor does not start. What is the problem?

Most likely, it is faulty starting capacitor or is turn-to-turn short circuit in the compressor windings. Check:

1. Capacitance of the capacitor (must be ±20% of the nominal value).
2. Resistance of the compressor windings (open or short circuit).
3. Voltage in the socket (can be below 180V).

How to distinguish a relay malfunction from a compressor breakdown?

Ring the compressor windings:

• Resistance between R and S must be equal to the sum of the resistances R–C and S–C.
• If the resistance of any winding = 0 or ∞, the compressor is faulty.
• If the windings are normal, but the motor is not starts - the relay or capacitor is to blame.

Can the relay be repaired or just replaced?

Electromechanical relays (RTP-1, DHR) are sometimes subject to repair:

• 🔧 Oxidized contacts —can be cleaned with sandpaper (fine grain).
• 🔩 Weak spring —bend them (carefully!).
• 🔥 Burnt contacts —cleaning helps in 50% of cases, but if the contact is burned through, only replacement.

Electronic relays (RSI) cannot be repaired - only replacement.

Where to buy a new relay and how much does it cost?

Relay prices in 2026:

• RTP-1 (tablet) - 300-600 rubles.
• DHR (Indesit) - 500-900 rubles.
• RSI (Samsung/LG) - 800-1,500 rubles.

Where to look:

• 🛒 Spare parts stores — “Cold”, “Rembytekhnika”, “220 Volt.”
• 🌍 Online — Wildberries, Ozon, AliExpress (but check the reviews!).
• 🔧 Service centers - sometimes they sell used relays after replacement.