How to check the refrigerator compressor motor yourself: detailed instructions

The compressor motor is the “heart” of the refrigerator, on which its performance depends. If the unit stops freezing, makes uncharacteristic sounds, or does not turn on at all, the first priority is to check the serviceability of the motor-compressor. In 70% of cases, refrigerator breakdowns are associated with this particular part, and timely diagnosis can save thousands on repairs.

In this article we will look at how to check the refrigerator compressor motor without calling a technicianusing available tools. You will learn what signs indicate a malfunction, how to correctly “ring” the windings with a multimeter, and what to do if the motor “hums” but does not start. The instructions are suitable for models Atlant, Indesit, Samsung, LG and other popular brands.

Signs of a faulty refrigerator compressor

Before taking up the tools, it is important to make sure that the problem is in the engine, and not in the thermostat, relay or freon leak. The following symptoms indicate a malfunction of the compressor:

• 🔊 The refrigerator does not turn on —there is no characteristic hum of the motor, the light inside is on, but there is no cooling.
• ❄️ It freezes poorly —the temperature in the chambers is higher than normal, the compressor works without stopping, but does not gain cold.
• ⚡ Protection is triggered —the motor starts for 1–2 seconds and turns off (relay clicks), then the cycle repeats.
• 🔥 Overheating of the housing —the compressor becomes hot to the touch, a burning smell appears.
• 💥 Extraordinary sounds - knocking, grinding or vibration during operation that was not there before.

If at least one of these signs appears, most likely the problem is in the engine. However do not rush to disassemble the refrigerator right away: in 30% of cases, the start-protection relay, which costs 5 times less than a compressor, is “to blame.”. To exclude false diagnostics, start with a visual inspection.

⚠️ Attention: If the refrigerator is connected to the network, do not touch to the metal parts of the compressor with bare hands - the housing can be under tension! Turn off the power and wait until the capacitors are completely discharged (5-10 minutes).

Preparation for diagnostics: tools and safety precautions

To check the compressor motor you will need:

• 🔧 Mulmeter (digital or pointer) with resistance measurement mode (ohmmeter).
• 🔌 Phillips/flat screwdriver — for removing the protective casing.
• 📏 Pliers —may be useful for disconnecting terminals.
• 🧲 Magnet (optional) - to check the tightness of the compressor housing.
• 📝 Notepad - to record winding resistance readings.

Before starting work:

1. Unplug the refrigerator and remove the plug from the socket.
2. Give access to the compressor - it is usually located in the lower part of the back wall.
3. If the compressor is hot, let it cool (at least 30 minutes).
4. Wear rubber gloves - this will protect against accidental electric shock.

It would be a good idea to photograph the location of the wires and terminals before disconnecting them. This will help avoid errors during reassembly. If you have never worked with electricity, it is better to invite an assistant - some operations require simultaneous measurement and fixation of contacts.

Visual inspection of the compressor: what to look for?

Start with an external inspection of the engine. Even without tools, you can identify obvious faults:

• 🔍 Cracks or swelling on the body - a sign of overheating or mechanical damage.
• 💧 Oil drips - indicate oil leakage from the crankcase, which leads to wear of the piston group.
• 🔌 Melted or blackened terminals —indicate a short circuit or overload.
• 🧲 Rust on tubes —may indicate a freon leak or moisture ingress.
• 🔊 Shaft play —if free movement is felt when rocking the compressor pulley, this is a sign of wear on the bearings.

Pay special attention start protection relay to the small box attached to the compressor. Often it is this that fails, simulating an engine breakdown. If the relay is cracked, melted, or smells like burning, replace it before further diagnostics.

How to check the compressor relay without a multimeter?

Disconnect the relay from the compressor and shake it - if you hear a knocking sound inside or The spring rattles, the part is faulty. Also inspect the contacts: blackening or carbon deposits indicate the need for replacement.

If everything appears in order, proceed to electrical checks. But first, make sure that the refrigerator is not under warranty - self-repair may deprive you of the right to free service.

Checking the compressor windings with a multimeter

This is a key diagnostic stage. The refrigerator compressor has three terminals:

• Common (C) — connected to the housing.
• Starting winding (S) —starts the engine.
• Working winding (R) —supports work.

Your task is to measure the resistance between these terminals. To do this:

1. Remove the terminals from the compressor (take a photo of their location first!).
2. Switch the multimeter to ohmmeter mode (200 Ohm range).
3. Attach the probes to pairs of contacts:
   • C → S (starting winding)
   • C → R (working winding)
   • S → R (total resistance)

Compare the readings with the standard ones (see table below).

If the resistance:

• 🔴 Equal to 0 —short circuit in the winding.
• 🔴 More than 100 Ohm —open circuit.
• 🟢 Within normal limits —the windings are in good condition.

Also check short circuit to the housing: attach one multimeter probe to the metal part of the compressor, the second to each terminal in turn. The resistance should tend to infinity (OL). If the device shows at least some value, the motor is faulty.

⚠️ Attention: For compressors with inverter control (for example, in models Samsung No Frost), the resistance of the windings may differ. For an accurate diagnosis, check the technical documentation for a specific model.

Checking the operation of the compressor under voltage

If the windings are working, but the refrigerator does not work, check the compressor under load. This test is dangerous —perform it only if you are confident in your skills!

Action algorithm:

1. Disconnect the start relay from the compressor.
2. Connect the compressor directly to the network via additional starting relay (can be temporarily taken from another refrigerator).
3. Shortly (for 1-2 seconds!) Apply power.

Possible results:

• 🟢 The compressor started and hums —a problem in the relay or thermostat.
• 🔴 Clicks, but does not start —interturn short circuit or jamming of the piston.
• 🔴 Sparks or smoke —immediately turn off the power! The compressor must be replaced.

If the motor starts but turns off after a few seconds, the reason may be:

• Faulty thermal sensor.
• Leakage freon (the compressor is idling).
• Clogging capillary tube.

Diagnostics without a multimeter: alternative methods

If you don’t have a tester at hand, you can check the compressor indirectly:

• 🔋 Checking the voltage in the socket - connect another device to it (for example, a hair dryer). If it works, the problem is not in the network.
• 🔊 Listening to the compressor - attach a screwdriver to the body and press your ear against the handle. In a working motor, a uniform hum is heard, in a faulty one, a grinding or knocking sound is heard.
• 🌡️ Temperature control - if the compressor works, but does not freeze, touch condenser (the grille at the back of the refrigerator). It should be warm. A cold condenser is a sign of a lack of freon.
• 💡 Light bulb test —connect an incandescent lamp (220V, 40–60W) in series with the compressor. If the lamp is lit at full intensity, the windings are intact; if it is not lit, there is a break.

These methods do not provide 100% accuracy, but they help narrow down the range of possible problems. For example, if the compressor does not start, but the light in the circuit lights up brightly, most likely turn-to-turn short circuit.

When is a compressor subject to repair and when is it necessary to replace it?

Not every compressor can be restored. Here are the criteria that will help you make a decision:

Compressor repair is justified only in three cases:

1. The refrigerator is expensive (premium class).
2. The breakdown is not critical (for example, an oil leak).
3. You have found a specialist with a guarantee for the work.

In all other situations, it is cheaper and more reliable to install a new compressor. When choosing a replacement, focus on:

• 🔹 Refrigerator model (for example, Atlant MXM 1705).
• 🔹 Freon type (R134a, R600a, etc.).
• 🔹 Power (indicated on the compressor nameplate).

⚠️ Attention: Prices for compressors and repairs may vary depending on the region and model of the refrigerator. Check current prices at service centers or on spare parts websites. (for example, 220-volt.ru, holodok.ru).

Common mistakes when checking a compressor

Even experienced technicians sometimes make mistakes that lead to an incorrect diagnosis. Here's what cannot be done when diagnosing:

• 🚫 Ring the windings without turning off the power - this can result in electric shock or damage to the multimeter.
• 🚫 Ignore the starting relay - in 40% of cases the problem is in it, and not in the compressor.
• 🚫 Measure the resistance on a cold motor - the readings may differ from the actual ones by 10-15%.
• 🚫 Apply voltage to compressor without a relay - this will lead to burnout of the windings.
• 🚫 Compare readings with data from the Internet —winding resistance depends on the compressor model.

Another common mistake is diagnostics by soundFor example, if the compressor hums but does not start, many immediately blame it. motor. However, the same symptoms occur with:

• Faulty thermostat.
• Clogged capillary tube.
• Low mains voltage (less than 200V).

Before changing the compressor, check these components!

🔹 Why does the refrigerator compressor get hot?

It is normal for the compressor to heat up to 50–60°C. due to:

• Freon compression (the main reason).
• Friction in bearings.
• High load (for example, during the first start after defrosting).

You should sound the alarm if the compressor housing burns your hand (more than 70°C) or heats up unevenly (one side is hotter than the other).

🔹 Is it possible to start the compressor without a relay?

No! data-i="264">Creating an initial current pulse.

• Creating an initial current pulse.
• Protection against overheating.
• Disconnecting the starting winding after acceleration.

Without a relay, the compressor will either not start or will burn out in a few seconds.

🔹 What multimeter is needed for testing?

Any digital or pointer tester with an ohmmeter mode (up to 200 ohms) is suitable. The main thing is that it accurately measures resistance up to tenths of an ohm. For professional diagnostics, megohmmeters (to check insulation) and current clamps (to control the inrush current) are used.

🔹 How much does it cost to replace a compressor at a service?

The cost depends on:

• Refrigerator model (spare part price - 5,000–15,000 ₽).
• Type of freon (R600a refill is cheaper, than R134a).
• Difficulty of work (in some models you need to disassemble the housing).

On average in Russia, replacement costs 8000–20000 ₽ (with spare parts and labor).

🔹 What to do if the compressor works, but not freezing?

The reasons may be the following:

• Freon leak (needs refilling).
• Clog in the capillary tube (needs cleaning or replacement).
• Malfunction of the thermostat (replacement sensor).
• Problems with the fan (in models with No Frost).

You can only remove the blockage yourself (by blowing with nitrogen) or replace the thermostat. For the rest, it is better to call a specialist.