How to correctly check the refrigerator relay with a multimeter: instructions with photos and diagrams

When the refrigerator suddenly stops freezing, but the light inside is on, and the compressor does not start or works intermittently, in 70% of cases it is to blame start-protective relay. This small plastic box, attached to the compressor housing, is responsible for starting the motor and protecting against overheating. Checking the relay with a multimeter is the first diagnostic step, which you can do yourself without calling a technician.

In this article you will find step-by-step instructions with photoshow to ring the relay contacts, check the resistance of the coil and windings of the compressor, and also find out what faults you can fix yourself, and when it is better to replace detail. We will analyze three types of relays (induction, posistor and electronic), which are installed in refrigerators Atlant, Indesit, Samsung, LG, Stinol, Biryusa and other brands.

Important: if you have never worked with electrical appliances, it is better to entrust the inspection to a specialist. But if you have basic skills in handling a tester and a screwdriver, follow our recommendations - this will save up to 3,000 rubles on diagnostics at a service center.

1. Signs of a faulty refrigerator relay

The relay rarely fails suddenly - it is usually preceded by characteristic “symptoms”. Here are the most common signs that the problem lies with it:

• 🔊 The compressor does not start, although the refrigerator is connected to the network and the indicators are on. Clicks are heard (the relay is trying to work), but the motor does not start.
• ⏱️ Short operating cycles: the compressor turns on for 5-10 seconds and immediately turns off. Repeats at intervals of 1–3 minutes.
• 🔥 The relay gets hot or smells burning. Touch the housing - if it is hot (more than 60°C), this is a sign of a malfunction.
• ⚡ The refrigerator is “electric shocking” when you touch the housing. This may indicate an insulation breakdown in the relay or compressor.
• 🛠️ Visible damage: melted plastic, blackened contacts, cracks on the case.

If at least one of these signs is present, the relay is needed check. But first, make sure that the problem is not thermostat or electronic board. To do this:

1. Disconnect the refrigerator from the network.
2. Find the thermostat (usually inside the chamber, under the plastic cover) and close its contacts with a jumper. If the compressor starts working, the thermostat is to blame; if not, check the relay.

⚠️ Attention: Do not touch the contacts of the relay and compressor when the power is on! The voltage in the circuit can reach 220V, which is life-threatening. Perform all measurements only after unplugging the refrigerator from the outlet.

2. Types of relays in refrigerators: how to determine yours

Before checking, you need to understand which relay is installed in your refrigerator. The nuances of diagnosis depend on this. There are three types in total:

To determine the type of relay in your refrigerator:

1. Unplug the refrigerator and move it away from the wall.
2. Remove the back cover (if there is one) or inspect the compressor from below.
3. Find the plastic box attached to the compressor - this is the relay. Take a photo of it and compare it with the table above.

If your relay does not look like any of those described, it may be combination relay with thermal protection (for example, 3RS or D2RL). with thermal protection

3. Preparation for testing: tools and safety measures

To diagnose the relay you will need:

• 🔧 Multimeter (digital or pointer) with dialing and resistance measurement modes (Ohm).
• 🔌 Phillips screwdriver for removing the relay cover (if there is one).
• 🧲 Magnet or marker for marking wires when disconnected.
• 📸 Smartphone for photographing the connection diagram.

Before starting work:

Take a photo of the wiring diagram for connecting the wires to the relay|

Unplug the refrigerator and wait for the capacitors to discharge (5-10 minutes)|

Prepare a workplace with a good lighting|

Wear rubber gloves to protect against accidental electric shock -->

If you remove the relay from the compressor, remember or sketch the location of the wires:

• Terminal 1 — common wire (from a 220V network).
• Terminal 2 - output to the compressor.
• Terminal 3 - starting winding of the compressor (sometimes marked with a letter S).

⚠️ Attention: In some models of refrigerators (for example, Samsung RL-33) the relay is integrated into the control board. Checking it requires special equipment and soldering skills. If you are not sure, do not take risks, contact the service.

4. multimeter

Induction relays are the most common in refrigerators of Soviet and post-Soviet production. Their testing includes three stages:

Step 1: Checking the coil resistance

The relay coil should have a resistance in the range 50–200 OhmIf the readings are multimeter 0 (short circuit) or ∞ (open), the coil is faulty.

1. Remove the relay cover (it can be secured with latches or screws).
2. Find the coil - this is a cylindrical part with a copper winding.
3. Connect the multimeter probes to the coil terminals (usually these are two legs going to the plate with contacts).
4. Set the resistance measurement mode (200 Ω) and measure value.

Example for relay RTK-XM (set in Atlant i Stinol):

Step 2: Checking the contacts

The relay contacts should close and open when voltage is applied to the coil. To check:

1. Connect the multimeter probes in continuity mode to the contacts 3 i 2 (starting and operating windings).
2. Shortly apply 220V voltage to the coil (for example, from a power supply or through an extension cord with a plug).
3. When voltage is applied, the contacts should close (the multimeter will emit a beep). After disconnection, open.

If the contacts are “stuck” (do not open after turning off the power) or do not close at all, the relay is faulty.

Step 3: Visual inspection

Inspect the relay contacts for:

• 🔥 Charring or melting.
• 💨 Soot (dark coating on the metal).
• 🛠️ Deformations springs or plates.

If carbon deposits can be carefully cleaned with fine sandpaper (zero), but in most cases it is better to replace such a relay - cleaning will give a temporary effect.

5. Checking a posistor relay (PTC)

PTC relays are used in modern refrigerators with inverter compressors. Their main difference is thermistor (posistor), which changes resistance depending on temperature. The test includes two tests:

Test 1: PTC resistance

At room temperature (20–25°C), the resistance of the PTC must be within 20–50 Ohm. When heated (for example, with a hair dryer), the resistance increases sharply (up to several kOhm).

1. Disconnect the relay from the compressor.
2. Connect the multimeter probes to the posistor terminals (usually these are two legs going to the round black tablet).
3. Measure the resistance. If it 0 or ∞ the posistor is broken or broken.
4. Heat the posistor with a hairdryer (not higher than 100°C!) and repeat the measurement. The resistance should increase by 10–100 times.

Example for a relay D2RL (set to Samsung RL-34):

• 🌡️ At 20°C: 30–40 Ohm.
• 🔥 At 80°C: 2–5 kOhm.

Test 2: Circuit continuity

Check for an open circuit between the relay terminals:

1. Set the multimeter to continuity mode.
2. Ring the circuits one by one:
   • Terminal 1 → posistor → terminal 2 (compressor).
   • Terminal 1 → thermal fuse → terminal 3 (start winding).

If at least one circuit does not ring, the relay is faulty.

⚠️ Attention: In some posistor relays (for example, in LG GA-B489) installed built-in thermal fuseIf it works. (resistance ∞), the relay must be replaced - the fuse cannot be restored.

6. Checking the electronic relay

Electronic relays found in refrigerators with system No Frost and inverter compressors (for example, Samsung RB-30, LG GA-B429). Their diagnosis is more difficult, since they do not have mechanical contacts and are controlled by a microcircuit.

The most reliable way to check is replace with a known good relay. follow these steps:

1. Turn off the refrigerator and remove the cover of the electronic unit (usually located next to the compressor).
2. Inspect the board for:
   • 🔥 Blackened or swollen capacitors.
   • 💥 Chips or cracks on the tracks.
   • 💧 Traces of oxidation or moisture.

Ring the power circuit:

• Between 220V input and compressor output.
• Between output to the temperature sensor and microcircuit.

If you find damaged elements (for example, a swollen capacitor), you can replace them yourself if you have a soldering iron. In other cases, it is better to contact the service.

How to check an electronic relay without replacement?

The only way is to use an oscilloscope to check the signals at the output of the chip. When the compressor starts, the operating relay should contain voltage pulses with an amplitude of 5–12V. Without an oscilloscope, diagnostics are impossible.

7. Typical mistakes when checking relays

Even experienced technicians sometimes make mistakes. errors that lead to incorrect diagnosis. Here are the most common:

• 🔌 Checking under voltage. Never touch the relay contacts with the multimeter probes when the refrigerator is plugged in! This can lead to electric shock or damage to the tester.
• 📉 Incorrect multimeter mode. mode 2000kΩ instead 200Ω will give incorrect readings.
• 🔄 Confusion with terminals. By mixing up the starting and working windings, you can mistakenly decide that the relay is faulty.
• 🌡️ Ignoring the temperature. The resistance of the posistor strongly depends on the temperature - measurements should be taken at 20–25°C.
• 🛠️ Cleaning contacts with sandpaper. This is a temporary solution - the deposit will return in 1-2 months.

Another common mistake is check. relay separate from the compressor, without taking into account that the problem may be in the motor. For example, if the compressor windings are closed, the relay will click, but will not start the engine. Therefore, always check resistance of the compressor windings:

• Working winding (R): 10–30 Ohm.
• Start winding (S): 30–50 Ohm.
• Resistance between R and S: sum of resistances R + S (40–80 Ohms).

If the resistance of the windings is not normal, the problem is in the compressor, not in relay.

8. When a relay needs to be replaced, and when it can be repaired

Not all relay malfunctions require its replacement. Here are the criteria that will help you make a decision:

Malfunction	Can it be repaired?	Cost of repair/replacement
Break or short circuit in the coil	❌ No	Replacement of relay: 800–2,500 rubles.
Soot on contacts	⚠️ Temporary (cleaning)	Free, but will require repeated cleaning after 1-3 months
The posistor does not work	❌ No	Replacement of relay: 1 200–3,000 rub.
Crack in the case	⚠️ Can be sealed with epoxy resin	Repair kit: 200–500 rub.
Oxidation terminals	✅ Yes (cleaning and lubrication)	Free

If you decide to replace the relay, choose analogue by catalog number (it is indicated on the body of the part). catalog number

• For Atlant MXM-170 suitable relay RTK-XM or LRS-12M.
• For Samsung RL-33 — D2RL-3 or PTC-11.
• For Indesit BIAA 13 — 3RS10.

The cost of a new relay depends on the type:

• 💰 Induction (RTK): 600–1,500 rubles.
• 💰 PTC (PTC): 1,200–2,500 rub.
• 💰 Electronic: 2,000–4,000 rub.

FAQ: Frequently asked questions about checking the refrigerator relay

Is it possible to check the relay without a multimeter?

Yes, but with limited accuracy. Turn off the refrigerator, remove the relay and shake it - if something rattles inside (for example, a broken spring), the relay is faulty. You can also apply 220V to the coil for a short time (via an extension cord) and listen: a working relay will click once, a faulty one will click repeatedly or remain silent.

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

This is a sign that the relay is working, but the problem is in the compressor. Check:

1. Resistance of the compressor windings (should be 10–50 Ohms).
2. Integrity of the starting capacitor (if your model has one).
3. Voltage in the socket (should be 220V ±10%).

If the compressor windings are broken or short-circuited, the motor will need to be replaced.

Which multimeter is best to use for testing?

Any digital multimeter with modes is suitable:

• Resistance measurements (up to 200 Ohms).
• Dials (with sound signal).
• Alternating voltage measurements (up to 500V).

Popular models: DT-830B, Mastech MS8229, UNI-T UT33D. Cost - from 300 to 1,500 rubles.

Is it possible to repair the relay with your own hands?

Yes, but only in case of mechanical faults:

• 🔧 Soot on the contacts: clean with fine sandpaper (zero) and wipe alcohol.
• 🧲 Oxidation of terminals: clean and cover with conductive grease.
• 🛠️ Crack in the housing: seal with epoxy resin.

Electrical faults (coil breakage, posistor breakdown) cannot be eliminated - replacement is required.

How long does it take to replace a relay?

On average 20–40 minutes, if you have experience working with technology. Beginners may need 1–1.5 hours. The longest stage is removing and installing the compressor cover (sometimes it is secured with latches that are difficult to unfasten).