Refrigerator compressor: how to check for functionality yourself

The compressor is the “heart” of the refrigerator, on which the cooling of the chambers and the safety of food depend. If the unit stops freezing, makes strange sounds or does not turn on at all, the first thought is a breakdown of the compressor motor. But before you call a technician or buy a new part, you should check the refrigerator compressor for operation do it yourself. In 60% of cases, the problem lies in the start relay, thermostat or freon leak, and not in the engine itself.

In this article you will find 7 proven diagnostic methods from visual inspection to testing with a multimeter. We will look at how to identify a malfunction without special tools, what sounds and signs should alert you, and also when to sound the alarm and contact a specialist. All instructions are adapted for popular models Atlant, Indesit, Samsung, LG, Bosch and are universal for most household refrigerators.

Important: if your refrigerator is still under warranty, disassembling it yourself may void it. In this case, it is better to immediately contact the service center. For the rest - forward to diagnosis!

1. Signs of a faulty compressor: when to sound the alarm

The first step is identify the symptomswhich indicate a possible breakdown of the compressor. The problem does not always lie there: for example, if the refrigerator does not cool, the thermostat, a freon leak, or a clogged capillary tube may be to blame. But there are “bells” that directly signal motor problems:

• 🔊 The compressor does not turn on at all - there is no characteristic hum, the refrigerator is silent. This may mean a break in the winding, a malfunction of the starting relay, or problems with the power supply.
• ⚡ The engine hums, but does not start —the sound of operation is heard, but the motor “stumbles” and turns off after 1-2 seconds. A common reason: interturn short circuit or wear of the piston group.
• ❄️ The refrigerator does not freeze well, but the compressor runs without stopping. There may be a drop in performance due to wear or lack of refrigerant.
• 🔥 The compressor housing gets very hot (hot even after 30 minutes of operation). The normal temperature is up to 60–70°C, but if it burns your hand, this is an alarming sign.
• 💥 Extraordinary sounds: knocking, grinding, vibration. May indicate destruction of bearings or valve failure.

If you observe at least one of these signs, it’s time to move on to a detailed check. But first, make sure that the problem is not in thermostat or start relay - these parts break more often, and their replacement is cheaper than repairing a compressor.

⚠️ Attention! If the refrigerator is connected to the network, but the compressor shows no signs of life (no hum, the housing does not heat up), first check socket i power cord. Perhaps the problem is a lack of power, and not a breakdown.

2. Preparing for diagnostics: what you will need

To check the refrigerator compressor, you do not have to be a professional technician. It is enough to have a minimum set of tools on hand and follow the instructions. Here's what you'll need:

• 🔧 Screwdriver (Phillips and flat) —to remove the back cover of the refrigerator and access the compressor.
• 📊 Multimeter —to check the winding resistance and voltage. Even a budget model is suitable (for example, DT-830B).
• 🔌 Socket tester or an indicator screwdriver - to make sure that the problem is not a lack of power.
• 🧲 Magnet (optional) - will help check whether the compressor rotor rotates (more details in the section about manual scroll).
• 📝 Notepad and pen - for recording multimeter readings (useful if you have to contact a technician).

Also prepare the refrigerator:

1. Turn it off from the mains and defrost (if there is ice in the freezer).
2. Move away from the wall to gain access to the back panel.
3. Remove the protective cover (usually it is attached to 4-6 screws).

On the back wall you will see a black “barrel” - this is the compressor. Next to it is located starting relay (a rectangular box with wires). It is with checking the relay that it is worth starting the diagnosis, since in 40% of cases the problem lies in it, and not in the motor itself.

3. Checking the starting relay: the first diagnostic step

The starting relay is a compressor “assistant” that supplies current to the windings at the time of starting. If the relay is faulty, the motor will either not turn on or will try. start, but immediately turn off. You can check it in 5 minutes:

1. Remove the relay It is attached to the latches or screws. Gently pull it up without pulling the wires.
2. Inspect the contactsIf they are burnt, melted or covered. plaque - the relay must be replaced.
3. Shake the relayIf something rattles inside, this is a sign of mechanical damage (for example, a broken spring).
4. Check multimeter:
   • Set the resistance test mode (200 Ohm).
   • Attach the probes to the coil contacts (usually the terminals S and M on the relay body).
   • Resistance should be within 15–40 Ohm. If the device shows 0 (short circuit) or ∞ (open), the relay is faulty.

If the relay is OK, go to checking the compressor itself. If not, replace it with a similar one (the model number is usually indicated on the case). The cost of a new relay for popular refrigerators (Indesit C132G, Atlant MHM 1705) is from 500 to 1500 rubles.

⚠️ Attention! Some modern refrigerators (for example, Samsung No Frost or LG Inverter) are equipped with electronic control boards instead of a classic relay. In this case, diagnostics become more complicated - you will need to check the signals from the board with an oscilloscope. If you are not confident in your skills, it is better to contact a specialist.

4. Checking the compressor without instruments: 3 simple tests

If you don’t have a multimeter at hand, you can do preliminary. diagnostics without tools, but they will help you understand whether to continue checking or immediately take the refrigerator for repair.

Test 1: Checking the heating of the body

Plug in the refrigerator and let the compressor run for 15–20 minutes. Then touch its body:

• ✅ Warm or hot (up to 60–70°C) - normal, the motor is running.
• ❌ Cold —the compressor does not start (problem in the relay, windings or power supply).
• ⚠️ Scalding hot (more than 80°C)—overheating is possible due to an interturn short circuit or malfunction valves.

Test 2: Manually turning the shaft

If the compressor hums but does not start, try manually turning its shaft. To do this:

1. Disconnect the refrigerator from the compressor. network.
2. Remove the starting relay (as described above).
3. Take a screwdriver with a magnetic tip or just a magnet.
4. Bring the magnet to the top of the compressor (where the shaft is). If the rotor rotates freely, the problem may be in the relay. If the shaft. “jammed” - the compressor is faulty.

Test 3: Checking for freon leakage

If the compressor works, but the refrigerator does not freeze, it may have occurred refrigerant leak. Signs:

• 🧊 The condenser (grid on the back wall) remains cold even after an hour of operation.
• 🔊 The compressor works without stopping, but the temperature in the chambers does not drop.
• 🛢️ Oil stains are visible on the pipes or compressor (freon leaves along with the oil).

If you suspect a leak, you won’t be able to fix it yourself - you will need evacuating the system refilling with freon. This is a job for a professional.

The socket and power cord were checked|The starting relay was inspected for damage|A test was carried out for heating the compressor housing|An attempt was made to manually rotate the shaft (if the motor hums, but does not start)|Freon leakage due to indirect reasons is excluded signs -->

5. Checking the compressor with a multimeter: step-by-step instructions

If preliminary tests do not give a clear answer, it’s time to arm yourself with a multimeter. We will check winding resistance the compressor and the integrity of the circuit. Here's how to do it correctly:

Step 1: Disconnection and access to terminals

Unplug the refrigerator. Remove the starting relay from the compressor - under it you will see three terminals (contacts), marked with letters:

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

Step 2: Measuring winding resistance

Switch the multimeter to resistance test mode (200 Ohms) and measure the readings between the terminals:

Example: if C→S = 30 Ohm, and C→R = 15 Ohmthen S→R should be 45 Ohm. If the multimeter shows otherwise, the compressor is faulty.

Step 3: Check for breakdown body

Switch the multimeter to the “continuity” mode (or measure resistance at a limit of 2 MOhm). Touch any terminal with one probe and the metal body of the compressor with the other. If the device shows any value except ∞, it means that breakdown of the winding to the housing has occurred - this is life-threatening (risk of electric shock) and requires replacing the compressor.

⚠️ Attention! If the compressor “pierces the housing”, its operation is prohibited! Even if it is still working, this is a direct path to a short circuit or electric shock.

What to do if the winding resistance is not normal?

If at least one of the measurements shows a deviation from the norm, the compressor is faulty. Depending on the problem:

- Winding break (resistance = ∞) - the compressor needs to be replaced.

- Interturn short circuit (resistance is below normal) - the motor will overheat and may burn out completely. Also replacement.

- Breakthrough to the housing —operation is prohibited, a new compressor is needed.

In rare cases, rewinding the windings helps, but this is expensive (from 3000 rubles) and not always justified for household refrigerators.

6. Checking current consumption: for experienced users

This method requires the presence of current clamps or a multimeter with a current measurement function (up to 10 A). It will help identify compressor overloadwhich often occurs when there is an interturn short circuit or wear of the piston group.

How to measure current:

1. Connect the refrigerator to the network.
2. Clamp one power wire of the compressor with a current clamp (or connect a multimeter to the open circuit).
3. Start the compressor. In the first seconds, the current can reach 1–1.5 A (starting current), then it should stabilize at the level 0.5–0.8 A.
4. If the current exceeds 1 A in operating mode, the compressor operates with an overload - this is a sign of a malfunction.

Also pay attention to the stability of the current:

• ✅ Smooth current no surges - the compressor is working.
• ❌ Jumps or drops to zero —problems with windings or mechanical parts.

This test is especially relevant for refrigerators with inverter compressors (Samsung Digital Inverter, LG Linear Compressor), where the current can vary widely. For them, normal values ​​are indicated in the technical documentation.

7. When the compressor is working, but the refrigerator is not working

Let's say you checked the compressor in all respects, and it turned out to be working. But the refrigerator still doesn't freeze. What could be the matter?

• 🌡️ The thermostat or temperature sensor is faulty. If it does not give a signal to turn on the compressor, the engine simply will not start. Check the thermostat with a multimeter (the resistance should change when you turn the knob).
• 🧊 Freon leak. The compressor works, but without refrigerant there will be no cooling. Signs: the condenser is cold, the tubes are covered with frost.
• 🔧 The capillary tube is clogged. If the system is clogged, freon does not circulate. The tube needs to be cleaned or replaced.
• 📱 Electronic board failure (in models with a display). For example, in Bosch KGE39XW25R or LG GA-B489YDQZ the board may block the start of the compressor.
• ⚡ Power problems: faulty socket, damaged power cord or blown fuse.

If you are not sure of the cause, try connect the compressor directlybypassing the thermostat and relay. To do this:

1. Remove the start relay.
2. Connect the compressor directly to the network (observing polarity!). Use a cable with a plug and female terminals.
3. If the motor starts and runs, the problem is in the relay or thermostat. If not, the compressor is faulty.

⚠️ Attention! Connecting the compressor directly is dangerous! Risk of electric shock or short circuit. Do this only if you are confident in your skills and use protective gloves.

FAQ: Frequently asked questions about checking the compressor

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

Yes, most tests (checking resistance, heating of the housing, manual rotation of the shaft) are carried out without dismantling. You only have to remove the start relay and the back cover.

What multimeter is needed for diagnostics?

Any digital multimeter with a resistance measurement mode will do (for example, DT-830B, Mastech MY64). To check the current, you will need a current clamp or a multimeter with a connector for measuring current up to 10 A.

The compressor hums, but does not start. What to do?

First check the starting relay (40% of cases). If the relay is working properly, try manually turning the compressor shaft with a screwdriver. If the motor does not start, there may be a break in the starting winding or mechanical failure (for example, a jammed piston).

How much does it cost to replace a compressor?

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

• Regular compressor (for example, for Atlant or Indesit) - from 3000 to 6000 rubles.
• Inverter compressor (for Samsung, LG) - from 8000 to 15000 rubles.
• The work of a replacement technician costs from 2000 to 5000 rubles.

For refrigerators older than 10 years, replacing a compressor is often not economically feasible - it is cheaper to buy a new unit.

Is it possible to repair the compressor or just replace it?

In most cases, the compressor is not repaired, but replaced. Exceptions:

• Replacement of oil (if it leaked out along with freon).
• Rewinding of windings (expensive and not always effective).
• Replacement of valves (in rare cases, if the piston group is working properly).

For household refrigerators, repairs are usually is not justified - it’s easier to install a new compressor.