How to independently check the serviceability of the refrigerator relay: step-by-step diagnostic methods

The refrigerator stopped freezing, Is the compressor not turning on or running intermittently? The reason may lie in a faulty start-up relay - a small but critical element of the system. This unit is responsible for starting the compressor and protecting against overloads, and its failure leads to malfunctions of the entire unit. In 80% of cases, a relay malfunction can be identified independently without calling a technician - it is enough to know where it is located and how to test it correctly.

In this article we will analyze 5 working methods for checking relays from visual inspection to diagnostics with a multimeter, and we will also tell you how to distinguish a relay failure from a compressor or thermostat malfunction. You'll learn what tools you'll need, how to interpret test results, and what to do if the relay actually fails. All instructions are adapted for popular models Atlant, Indesit, Samsung and LG, but are also applicable to other brands.

What is a relay in a refrigerator and how does it work

A start-up protection relay is an electromechanical (or electronic) device that performs two key functions:

• 🔌 Starting the compressor: when power is applied, the relay closes the starting winding circuit, helping the motor overcome the initial load.
• 🛡️ Overheat protection: if the current in the compressor windings exceeds the norm (for example, due to jamming), the relay opens the circuit, preventing damage to the motor.

Most household refrigerators use two types of relays:

• 🔄 Electromechanical (induction or tablet): installed on models older than 10 years (Birusa, Nord, Stinol). They have moving contacts and a coil.
• 📱 Electronic (posistor): modern relays without moving parts, used in Samsung No Frost, LG Inverter and other refrigerators with inverter compressors.

The relay is attached directly to the compressor housing (usually on the side or top) and is connected via a terminal block with 2-4 contacts. In some models (for example, Atlant MXM-1705), the relay is integrated into a single unit with a thermostat - this complicates diagnostics, but does not make it impossible.

Symptoms of a faulty refrigerator relay

Before checking the relay, make sure that it is the problem. The following symptoms indicate a malfunction of the unit:

It is important to distinguish a relay failure from a malfunction of the compressor or thermostat. For example, if the refrigerator Indesit BIAA 13 does not freeze, but the light inside is on, the problem may be:

• 🔌 Relay - if the compressor does not start at all.
• ❄️ Thermostat - if the compressor does not turn on, but the relay clicks.
• 🔧 Compressor - if the relay is working properly, but the motor hums and gets hot.

Preparation for testing: tools and safety measures

To diagnose the relay you will need:

• 🔧 Phillips/flathead screwdriver — to dismantle the protective casing.
• 📊 Multimeter (or tester) - to check resistance and voltage.
• 🔌 Extension cord with lamp (load 100–150 W) - for testing under voltage.
• 🧤 Dielectric gloves —required when working with the refrigerator turned on.

Before starting work:

1. Disconnect the refrigerator from the mains and defrost it (if it has not thawed more than 24 hours).
2. Get access to the compressor - it is usually located at the bottom of the rear wall.
3. Take a photo of the relay connection diagram (especially if the wires are not marked).

⚠️ Attention: If The refrigerator compressor is hot (temperature above 60°C), allow it to cool for at least 1 hour. Testing the relay on a hot motor may give false results due to thermal expansion of the contacts.

Method 1: Visual inspection of the relay

Start with an external inspection of the device. Remove the relay from the compressor (usually it is attached with latches or screws) and check:

• 🔥 Melted or blackened contacts —a sign of overheating due to increased current.
• 💥 Cracks in the housing —may indicate mechanical damage.
• 🧲 Foreign particles inside (for example, rust or dirt) - lead to short circuits.
• 🔌 Oxidation terminals - worsen contact and can simulate a malfunction.

Pay special attention starting contact (usually it is marked with a letter S or Start). If it is burnt, the relay must be replaced. In electronic relays (for example, in refrigerators Samsung RL-33), visually check the condition of the posistor - it should not be swollen or cracked.

If there is a marking on the relay body (for example, DANFOSS 103N0210 or RBM-1), write it down - this will help you find a similar replacement. In refrigerators Atlant relays are often installed RTK-X, and in LG — RL3-1 or RLS-4.

How to distinguish a starting relay from a protective relay?

In most refrigerators, these two elements are combined into one unit. However, in older models (for example ZIL-63 or Minsk-15M) they can be separated. The starting relay is responsible for starting the compressor, and the protective relay is responsible for shutting down when overheating. Visually, the protective relay often has a bimetallic plate, and the starting relay has an inductor coil.

Method 2: Checking the relay with a multimeter (without removing it from the refrigerator)

This method is suitable for electromechanical relays and allows you to evaluate the condition of the windings and contacts without dismantling. Follow the steps:

1. Disconnect the refrigerator from the mains and remove the terminals from the relay (remember their location!).
2. Switch the multimeter to resistance measurement mode (range 200 Ohm).
3. Ring the relay contacts:
   • Between the terminals S (starting) and M (total) the resistance should be 15–40 Ohm.
   • Between M and R (working) - 5–20 Ohm.
   • Between S and R — infinity (no connection).

If the readings differ from the norm, the relay is faulty.

For electronic relays (posistor), checking with a multimeter is less informative, but you can measure the resistance of the posistor at room temperature - it should be 20–50 Ohm. When heated (for example, with a hairdryer), the resistance should increase sharply (up to several kOhms).

⚠️ Attention: In refrigerators with inverter compressors (Panasonic NR-B, Toshiba GR), the relay is often integrated into the control board. Checking such systems requires special equipment and skills to work with. electronics.

Method 3: Test. energized relay (for experienced users)

This method allows you to check relay operation in real conditions, but requires caution. Connect the relay to the network through a load (for example, a 100 W incandescent lamp) according to the following scheme:

1. Disconnect the relay from the compressor, but leave the power wires connected.
2. In parallel with the compressor contacts (M and S) connect the lamp.
3. Plug in the refrigerator. A working relay should:
   • 💡 Close the circuit for 1-2 seconds (the lamp will light up).
   • 🔄 Open the contact S after starting (the lamp will go out).

If the lamp does not light up or is on permanently, the relay is faulty. In refrigerators with electronic control (Liebert, Beko CN), such a test may not work - instead of a lamp, use a multimeter in voltage measurement mode (200 V AC).

When testing a relay under voltage, never touch the bare contacts with your bare hands - even with the power off, a charge of up to 300 V may remain on the capacitors.

Method 4: Testing by replacing with a known good relay

If you have access to a working relay (for example, from another refrigerator of the same model), the most reliable diagnostic method is a temporary replacement. To do this:

1. Remove the faulty relay from the compressor, remembering the location of the wires.
2. Install a working analog (make sure the models match!).
3. Turn on the refrigerator and check:
   • 🔊 Whether the compressor starts.
   • ⏱️ Does the on/off cycle work (usually 10-20 minutes of operation, 5-10 minutes of rest).

If after replacement the refrigerator works normally, the problem is definitely in the relay. Please note that even seemingly identical relays may have different characteristics (for example, RTK-X-1 and RTK-X-2 differ in operating current for models). data-i="211">i Samsung And LG it is better to select an analogue based on the compressor serial number.

Method 5: Diagnostics by indirect signs (without tools)

If you don’t have a multimeter or a spare relay at hand, you can assess its condition by indirect signs:

• 🔊 Clicks without starting the compressor: the relay is activated, but the contacts do not close (possibly oxidized or burnt).
• 🔥 Burning smell from under the rear panel: indicates for melting of contacts or windings.
• ⏳ Start delay (more than 5 seconds after the click): a sign of wear on the relay starting winding.
• 🌡️ The compressor is hot, but does not start: the relay blocks the start due to false operation protection.

In refrigerators with a system No Frost (Indesit NBA 18, Bosch KGN39), a faulty relay can lead to icing of the evaporator - check if ice is building up on the back wall of the freezer.

If the relay clicks, but the compressor does not start, try lightly tapping the relay body with a screwdriver (without fanaticism!). Sometimes this helps to “unstick” the stuck contacts. If after this the refrigerator starts working, the relay still needs to be replaced - this is a temporary measure.

What to do if the relay is faulty: repair or replacement

In most cases In some cases, a faulty relay must be replaced, but some breakdowns can be fixed independently:

The cost of a new relay for a refrigerator varies from 500 to 2500 rubles. depending on the model. For replacement:

1. Buy a relay with identical characteristics (operation current, number of contacts).
2. Disconnect the refrigerator from the network and remove the old relay.
3. Install a new one, observing the polarity of the connection (usually the terminals are marked).
4. Check the operation of the refrigerator within 1–2 hours.

⚠️ Attention: In refrigerators with inverter compressors (Sharp SJ-FX620, Mitsubishi MR-CR46), replacing the relay may require flashing the control board. In such cases, it is better to contact a service center.

FAQ: Frequently asked questions about checking the relay. refrigerator

Is it possible to check the relay without removing it from the refrigerator?

Yes, but only with a multimeter in test mode. Disconnect the refrigerator from the network, remove the terminals from the relay and measure the resistance between the contacts M-S And M-R. the readings correspond to the norm (see section "Method 2"), the relay is working properly. However, for accurate diagnostics, dismantling is recommended. Why does the relay click, but the compressor does not start? the problem may be in the compressor itself (rotor jamming) or in low network voltage (less than 190 V). Check the relay by replacement or live test (see "Method 3").

Why does the relay click but the compressor does not start?

This is a typical sign contact burning or start winding breakage in the relay. The problem may also be in the compressor itself (rotor jamming) or in low network voltage (less than 190 V). Test the relay by replacement or live test (see "Method 3").

What multimeter is needed to check relay?

An inexpensive multimeter with a mode for measuring resistance (up to 200 Ohms) and alternating voltage (up to 250 V) is sufficient. Models DT-830B, Mastech MS8229 or analogs are suitable. The main thing is that the device has accurate readings in the range of low resistances (up to 50 Ohms).

How much does it cost? replacing the relay at a service center?

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

• Replacement of an electromechanical relay: 1000–1800 rubles.
• Replacement of an electronic relay (in inverter models): 2000–3500 rubles.
• Diagnostics + replacement: 1500–2500 rubles.

Prices are relevant for Moscow and St. Petersburg In the regions, the cost may be different. 20–30% lower.

Can I use a relay from another refrigerator model?

Yes, but only if they match:

• Relay type (electromechanical/electronic).
• Rated current (indicated on the body, for example, 5A or 10A).
• Connection diagram (number and location of terminals).

For example, a relay Danfoss 103N0210 is suitable for many models Atlant and Indesit, and RL3-1 - for LG and Samsung with linear compressors. For inverter models (Hitachi R-W660) specialized relays are required.