How to correctly check the refrigerator compressor windings with a multimeter

When the refrigerator stops freezing, but the light inside is on and the fan is working, the problem often lies in the compressor. One of the key diagnostic tests is checking the integrity of the motor windings. This procedure allows you to identify interturn short circuitsbreaks or breakdowns in the housing without disassembling the system.

In this article you will find step-by-step instructions with photoshow to ring the windings of a refrigerator compressor Atlant, Indesit, Samsung and other brands. We will look at:

• 🔧 What tools are needed and how to prepare the compressor
• 📊 Normal resistance values for different types of windings
• ⚡ Typical malfunctions and their “symptoms” in operation refrigerator
• 🛠️ What to do if the winding is “broken” or the resistance does not meet the standard

Important: testing windings requires basic skills in working with electricity. If you have never held a multimeter in your hands, it is better to entrust the diagnosis to a specialist. Checking under voltage without disconnecting the capacitor can lead to electric shock even when the refrigerator is turned off!

1. Preparing for testing: tools and safety precautions

Before starting testing, make sure that the refrigerator is completely de-energized. Unplug the plug from the socket and wait 10-15 minutes - this time is necessary for the discharge starting capacitorwhich can store a dangerous charge.

You will need:

• 🔹 Multimeter (digital or pointer) with resistance measurement mode (ohmmeter)
• 🔹 Phillips screwdriver for removing the compressor protective casing
• 🔹 Pliers or wire cutters to disconnect the terminals (if necessary)
• 🔹 Insulating tape or heat shrink tube for marking wires
• 🔹 Flashlight - the compressor is usually located at the bottom of the refrigerator in a poorly lit place

⚠️ Attention: If the compressor is hot to the touch, let it cool for at least 1 hour. Overheating can distort the multimeter readings.

Before disconnecting the wires, take a photograph of their location on the compressor terminals. This will help avoid errors when connecting back. Most models (Samsung RL34ECMS, Indesit DF 4180) use standard markings:

• S — starting winding
• R — working winding
• C — general output

Disconnect the refrigerator from the network|Remove the rear protective panel|Take a photo of the connection diagram wires|Discharge the capacitor (short-circuit its terminals with a screwdriver with an insulated handle)|Clean the compressor terminals from oxidation-->

2. Connection diagram for refrigerator compressor windings

A refrigerator compressor is asynchronous electric motor with two windings: working and starting. Their resistances are summed up at the common terminal (C). A typical connection diagram looks like this:

In practice, the values may differ depending on the compressor model. For example, the resistance of the working winding is ~12 Ohms, and the starting winding is ~25 Ohms. Danfoss SC10H The resistance of the working winding is ~12 Ohms, and the starting winding is ~25 Ohms. U Embraco EGX 90HLC these indicators are higher: 18 Ohms and 35 Ohms, respectively.

If your compressor does not have terminal markings, be guided by their location:

• 🔸 Common terminal (C) usually located in the middle.
• 🔸 The terminals on the sides are S (starting) and R (working). To distinguish them, measure the resistance between each terminal and the common terminal: a lower value will indicate the working winding.

⚠️ Attention: On some models (LG GA-B409) non-standard pinout is used. If the resistance between all terminals is the same, check the compressor documentation.

3. Step-by-step instructions: how to test the windings with a multimeter

The testing algorithm is the same for all types. compressors (Secop, Embraco, Mitsubishi):

1. Disconnect the wires from the compressor terminals. If they are attached using lugs, carefully remove them with pliers.
2. Install the multimeter to resistance measurement mode (200 Ohm range).
3. Ring the windings:
   • 🔹 S → C (starting)
   • 🔹 R → C (working)
   • 🔹 S → R (total)

Check the breakdown on the housing: one multimeter probe press it to the metal body of the compressor, connect the second one in turn to each terminal. The resistance should tend to infinity (OL on the screen).

Example of correct readings for the compressor Embraco NM 1200:

• S–C: 32 Ohm
• R–C: 15 Ohm
• S–R: 47 Ohm
• Case - any terminal: OL (no breakdown)

What to do if the resistance between S and R is equal to the sum of S–C + R–C?

This is normal! According to Ohm's law, the resistances of the windings add up when connected in series. For example, if S–C = 30 Ohms and R–C = 15 Ohms, then S–R should be 45 Ohms. A deviation of more than 10% indicates a malfunction.

If the multimeter readings:

• 🔴 0 Ohm (short circuit) - the winding is broken.
• 🔴 OL (break) - the winding is broken.
• 🔴 Resistance between the terminal and the body < 100 kOhm - breakdown at housing.

4. Typical winding faults and their symptoms

Problems with windings manifest themselves differently depending on the type of fault:

For example, if a refrigerator Beko CN 325120 turns on for 2-3 seconds and turns off with a loud click - this is a typical sign interturn short circuit in the starting winding. In this case, the working winding may be in good condition. and the multimeter will show normal resistance R–C.

Another case: the refrigerator Liebherr CTPes 3556 does not respond at all to being turned on, but the light inside is on. When checking, it turns out that the resistance R–C = OL is break of the working winding.

5. Common mistakes when checking windings

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

• 🚫 Test without disconnecting the capacitor. A capacitor can distort the multimeter readings. Always disconnect it before testing.
• 🚫 Ignoring the compressor temperature. A cold motor will show a resistance 10-15% lower than a hot one.
• 🚫 Incorrect range selection on the multimeter. If you measure the winding resistance (10–40 Ohm) in 2 MOhm mode, the device will show “0”.
• 🚫 Confusion with terminals. On some compressors (Secop SL), the common terminal may be not in the center, but on the left.

Another typical mistake is checking the windings “in weight” when the compressor is not secured. Vibration during operation can disrupt the contacts, and the test will show a false break. Always fix the compressor or carry out the test in the assembled state (disconnecting only the wires).

⚠️ Attention: If you are using a dial multimeter, reset it to zero before measuring (align the arrows). Digital devices do not need this.

6. What to do if the windings are faulty?

Unfortunately Repairing compressor windings at home is impossible. Interturn short circuits or breaks can only be eliminated in the factory using special equipment. In 99% of cases, a faulty compressor must be replaced.

Algorithm of action:

1. Check the warranty. If the refrigerator is less than 5 years old, replacement of the compressor may be covered by the warranty (even if it does not cover electrical parts, service centers often go towards you).
2. Compare the cost of repairs and a new refrigerator. Replacing a compressor costs 50–70% of the price of a new unit. For models older than 10 years (Stinol 102, Minsk 126), repairs are usually unprofitable.
3. Select a donor compressor. If If you decide to replace it yourself, select a model with identical ones:
   • 🔹 Refrigerant (R134a, R600a)
   • 🔹 Power (hp or kW)
   • 🔹 Mounting type (flange)

Example of selection of replacement:

• Original compressor: Embraco EGX 90HLC (R134a, 1/4 hp)
• Analogs: Secop (Danfoss) SLJ90 or Mitsubishi TC-C90K

If you decide to replace the compressor yourself, do not forget:

• 🔧 Replace filter drier (it accumulates moisture and dirt).
• 🔧 Check start relay —it may be designed for a specific compressor model.
• 🔧 Evacuate the system before charging refrigerant (a vacuum pump is required).

7. When the compressor is not to blame: alternative causes of malfunctions

If the compressor windings are working properly, but the refrigerator does not work, check:

• 🔍 Start relay. If there is a malfunction, it does not supply voltage to the starting winding. Symptom: The compressor hums, but does not start. The relay can be checked by short-circuiting its contacts with a screwdriver (be careful!).
• 🔍 Thermostat. If it does not close the contacts, the compressor will not receive a start command. Check with a multimeter in continuity mode: when you turn the knob to minimum, the contacts should close.
• 🔍 Condenser. A swollen or leaking capacitor does not provide the required starting current. Its capacity can be measured with a multimeter with the appropriate function.
• 🔍 Refrigerant leakage. If the compressor works but does not freeze, there may be no freon in the system. Symptom: the condenser (grid at the back) remains cold.

For example, in refrigerators Nord i Birusa the thermostat often fails. K-59. It can be temporarily closed to check: if the compressor starts working, it is the problem.

⚠️ Attention: Refrigerator parts may vary depending on the year of manufacture. For example, in Atlant MXM 1705-80 before 2018, relays were installed RLS-3, and after - RLS-4. Check the components by the serial number of the model.

FAQ: Frequently asked questions about checking compressor windings

Is it possible to check the windings without removing the compressor?

Yes, but to do this you need to disconnect all wires from the compressor terminals. The test itself can be carried out without dismantling if there is access to the terminal block. However, to replace the compressor you will still have to remove it.

What resistance should a working compressor have?

For most household refrigerators:

• Working winding (R–C): 10–20 Ohm
• Start winding (S–C): 20–40 Ohm
• Total (S–R): 30–60 Ohm

The exact values depend on the model and are indicated in the technical data sheet compressor.

What to do if the multimeter shows 1-2 Ohms instead of 15-20?

This is a sign turn-to-turn short circuit. The winding is broken and the compressor needs to be replaced. Attempting repairs (for example, rewinding) at home is impractical - after such repairs, the life of the compressor will be reduced by 5–10 times.

Can a compressor operate with a faulty starting winding?

No, without a starting winding windings, the compressor will not be able to start. However, if the winding is not completely broken, but has increased resistance, the compressor may start with difficulty, overheat and turn off after a few seconds.

How to distinguish a faulty winding from a problem with the relay?

If the windings are OK, but the compressor does not start:

1. Check that Does the relay click when you turn on the refrigerator? If not, the relay is faulty.
2. Close the relay contacts with a screwdriver (for 1-2 seconds!). If the compressor starts working, the problem is in the relay.
3. Look at the capacitor: if it is swollen or electrolyte has leaked, replace it.