How to check the refrigerator compressor for performance at home: a step-by-step guide

The compressor is the “heart” of the refrigerator, and its breakdown means stopping the entire cooling system. If your unit stops freezing, makes strange sounds, or doesn’t turn on at all, the first thought is that the compressor is to blame. But before you take your equipment to a service center or buy a new motor, you should make sure that this is the problem. In 60% of cases, the fault lies in the start relay, thermostat or freon leak - and these breakdowns can be fixed cheaper and easier.

In this article you will learn how diagnostics of the refrigerator compressor with your own hands without professional equipment. We will analyze mechanical and electrical testing methods, learn to “listen” to the motor, test the windings with a multimeter and check the pressure in the system. All instructions are adapted for beginners - with photos, diagrams and explanations of technical terms. Important: some tests require accuracy, but do not pose a danger if you follow the rules.

Let's start diagnostics - let's start with the simplest and gradually move on to more complex ones methods.

1. Preliminary diagnostics: symptoms of a faulty compressor

Before disassembling the refrigerator, check indirect signswhich will indicate a problem with the compressor. Here are the typical “symptoms”:

• 🔊 The refrigerator does not turn on —there is no sound of a running motor, the light inside is on, but there is no cooling.
• ❄️ Not freezing —it is warm in the chambers, despite the set mode (for example, -18°C in the freezer).
• ⚡ The compressor turns on for 1-2 seconds and turns off —the relay clicks, but the motor does not start.
• 🔥 Overheating of the housing —the compressor is hot to the touch (normal: up to 60°C, critical: above 90°C).
• 💣 Loud knocking or vibration - the motor “beats” during operation, metallic blows are heard.

If at least one of these signs is present, proceed to a detailed check. But first rule out simple reasons:

• 🔌 Power - make sure that the plug is tightly inserted into the socket, there are no power surges (check with other devices).
• 🌡️ Thermostat - turn the temperature control knob to maximum - if the compressor starts working, the problem is in the sensor.
• 🚪 Door —a poor seal seal or an open door can cause the motor to constantly run.

Important! If the refrigerator Indesit, Atlant or Samsung is older than 10 years, the compressor could wear out naturally. In new models (for example LG Inverter or Bosch VitaFresh) the motors last longer, but are sensitive to voltage changes.

2. Visual inspection of the compressor: what can be seen without tools

Start with an external inspection. The compressor is located at the back of the refrigerator in the lower part (sometimes hidden under the panel). Unplug the equipment and move it away from the wall for access.

What to check:

• 🔧 Compressor housing —there should be no cracks, traces of oil or rust. Oil on the floor under the refrigerator indicates depressurization. systems.
• 🔌 Wires and contacts —melted insulation, blackened or oxidized terminals indicate a short circuit.
• 📏 Motor position —the compressor must stand level, without distortions. If it “falls over,” check. fastenings.
• 🧲 Start relay - small box on the compressor. If it is cracked or melted, it needs to be replaced.

Pay attention to condenser (grid at the back of the refrigerator). If it is dirty with dust or bent, this impairs heat transfer and causes the compressor to wear out. Clean it with a soft brush.

⚠️ Attention: If there are swellings or traces of corrosion on the compressor housing, it cannot be turned on - this is a sign of internal damage, which can lead to rupture.

3. Checking the compressor by sound: what should alert you

Sound diagnostics is the fastest way to identify problems. Turn on the refrigerator and listen to the normal operation of the compressor. how uniform humming without sudden changes in tone. Here's what should alert you:

If the compressor turns on and turns off immediately, this is a sign of operation thermal protection. The reason is overheating of the windings or an interturn short circuit. In this case, the motor needs to be ringed.

Why can a new compressor knock?

A knocking sound in a new compressor (for example, after replacement) is often caused by incomplete pumping of oil through the system. This is a temporary phenomenon that disappears after 1-2 hours of operation. If the knocking does not disappear, it may be defective or incorrectly installed.

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

For electrical diagnostics. you will need multimeter (even a budget model will do). We will check winding resistance the compressor and the integrity of the circuit. Here's how to do it:

Step 1. Disconnect the refrigerator from the network and remove the starting relay (disconnect the terminals, unscrew the fasteners). Under the relay you will see three contacts of the compressor:

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

Step 2. Ring the windings:

1. Set the multimeter in resistance measurement mode (Ω) to the limit 200 Ohm.
2. Measure the resistance between C and S (start winding) - norm: 20–40 Ohm.
3. Measure between C i R (working winding) - norm: 10–20 Ohm.
4. Measure between S and R - it should be infinite resistance (break).

Step 3. Check for a short to the case:

• Connect one multimeter probe to the metal body of the compressor.
• Use the second probe, alternately touch the contacts C, S and R.
• If the device shows any resistance (except ∞) - the compressor is broken, replacement is required.

Critical value: if the resistance between S and R is less than 10 Ohms, there is an interturn short circuit in the windings. Such a compressor cannot be turned on; it will burn out upon startup.

⚠️ Attention: If during measurements the multimeter shows 0 Ohm between any contacts (except S-R), this means a short circuit. Turning on such a compressor will lead to a fire or failure of the refrigerator electronics.

5. Checking the pressure in the system: how to understand if there is freon

If the compressor turns on, but the refrigerator does not cool, it is possible Freon leak. It is difficult to check this without a manometric manifold, but there are indirect methods:

Method 1. Tactile test of the capacitor:

• Turn on the refrigerator and wait 10-15 minutes.
• Touch capacitor (grid at the back). Normally, it should be warm (about 40–50°C).
• If the condenser cold there is no freon or there is too little of it.
• If the condenser hot (above 60°C) - the compressor may be overloaded or the capillary tube may be clogged.

Method 2. Checking the tubes:

• Find two tubes coming from the compressor:
• 🔹 Thick (suction) - should be cool and wet (due to condensation).
• 🔹 Thin (discharge) - should be hot.
• If the thin tube is cold, there is no freon or the compressor does not pump.

For accurate diagnosis it is needed manometric manifold, but its purchase is justified only for professionals. At home, a tactile method is sufficient.

6. Checking the start relay: why the compressor does not start

In 30% of cases, an “imaginary” breakdown of the compressor is associated with relay. This part supplies current to the windings at the time of starting. If the relay is faulty, the motor will not be able to start.

How to check the relay:

1. Remove the relay from the compressor (disconnect the terminals and unscrew the fasteners).
2. Shake the part - if something rattles inside, this is a sign of mechanical wear.
3. Ring the contacts multimeter in the mode Ω:
• The resistance between the terminals C and P (or L) should be 0 Ohm (closed).
• Between C and S is infinity (∞).

If the readings are different, the relay is faulty.

Also inspect relay coil (if it is in your model). A melted or blackened coil is a sign of overheating. In this case, the relay must be replaced.

For models with positor relay (for example, Samsung RL-33 or LG GC-B247) more complicated - you need a circuit. If you are not sure, it is easier to buy a new relay (costs from 500 ₽).

⚠️ Attention: Some relays (for example, in refrigerators Atlant or Stinol) have a built-in thermal fuse. If it triggered, the relay will not pass current, even if it is in good condition. In this case, you need to wait 10-15 minutes before automatic reset.

7. When the compressor needs to be replaced: signs of irreversible damage.

Not all compressor malfunctions can be eliminated. Here are the cases when replacement is required:

• 🔥 Interturn short circuit —the winding resistance is below normal or equal to 0 Ohm.
• ⚡ Breakdown to the housing - any resistance between the windings and the metal body.
• 💥 Mechanical failure - knocking, piston jamming, cracks in the housing.
• 🛢️ Oil leakage - if from the compressor oil is leaking, the seal is broken.
• 🔄 Insufficient performance —the motor runs, but does not create the required pressure (checked with a pressure gauge).

The cost of a new compressor is from 3 000 ₽ (for budget models) to 15 000 ₽ (for invertermotors Samsung or LGIt is better to entrust the replacement to a specialist, as it requires:

• Vacuuming. systems;
• Refilling freon;
• Soldering tubes;
• Setting the thermostat.

If your refrigerator is over 10 years old, it is sometimes cheaper to buy a new one than to repair the compressor. For example, replacing the motor in Atlant MXM-1708 can cost half the price of a refrigerator.

Frequently asked questions about checking the compressor

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

Yes, Some tests are carried out without dismantling:

• Listening to operating sounds;
• Checking the temperature of the condenser and tubes;
• Measuring the resistance of the windings (if there is access to the contacts).

But for accurate diagnostics (for example, checking pressure), the compressor will be needed disconnect.

How to distinguish a compressor failure from a thermostat failure?

If the thermostat is broken, the compressor will not turn on at all. (even for a short time) the motor:

• Either it tries to start and immediately turns off;
• Or it works, but does not create cold;
• Or it makes atypical sounds (knocks, vibration).

Also check the thermostat by turning its knob to maximum - if the compressor is working, the problem is in the sensor.

What to do if the compressor hums but does not start?

This is a typical sign of:

• Faulty starter relay (in 70% of cases);
• Breakage in starting winding;
• Stuck piston (if the motor is overheated).

Replace the relay first - this is the cheapest way. If this does not help, test the windings with a multimeter.

How much does it cost to diagnose a compressor in a service?

Prices depend on the region and model of the refrigerator:

• 500–1 500 ₽ — technician visit and basic diagnostics;
• 1 000–3 000 ₽ — inspection with disassembly and pressure test;
• 3 000–6 000 ₽ — complete diagnostics with refilling freon (if necessary).

In some services, diagnostics are free if you agree to have them repaired.

Is it possible to turn on a refrigerator with a faulty compressor?

Categorically no! If the compressor:

• Has an inter-turn short circuit - this will lead to a fire;
• Stuck - the motor will burn when you try to start;
• Punched into the body - danger of electric shock.

Exception: if you are sure that the problem is in the relay or thermostat, you can temporarily connect the compressor directly (bypassing the relay) for a test.