When the refrigerator suddenly stops freezing or makes suspicious sounds, the first thing that comes to mind is problems with the compressor. This unit, often called the “heart” of the equipment, is responsible for circulating the refrigerant and maintaining the desired temperature. But how do you know if it is working? One of the key indicators is winding resistance, measured in ohms (Ohm). If you've never dealt with electrical measurements, the topic may seem daunting. In fact, even a beginner can check a compressor with a multimeter - the main thing is to know what values are considered normal and how to interpret them correctly.
In this article we will figure out how many ohms should be in a working compressor refrigerators Atlant, Indesit, Samsung and other popular brands, we will learn to distinguish the starting winding from the working winding, and also find out what to do if the multimeter readings are outside the permissible values. You will learn why resistance can “go” to zero or infinity, and when to sound the alarm. For clarity, we will provide tables with typical values for different models and give step-by-step instructions for diagnostics - without water and unnecessary theory.
Why compressor resistance is important for diagnostics
A refrigerator compressor is electric motorwith two windings located inside: working (main) and starting (start). Their resistance is a kind of “health passport” of the motor. If the windings overheat, short out or break, their resistance changes, which is immediately visible when measured with a multimeter. For example:
- 🔥 Resistance is close to 0 Ohm is a sign of a short circuit (the windings are “burnt out” and are in contact with each other).
- ∞ Resistance tends to infinity —open circuit (the conductor is damaged).
- ⚠️ Values go beyond the limits norms (for example, 15 Ohms instead of 20)—turn-to-turn breakdown or insulation wear is possible.
Without checking the resistance, you risk installing a faulty compressor back or, worse, burning a new part due to hidden defects. For example, if the starting winding is “broken,” the motor may start with difficulty, heat up and eventually fail in a few days. In 80% of cases of unstable operation of the refrigerator (does not freeze, does not turn off, hums), the compressor is to blame - and the resistance of the windings helps confirm or refute this in 5 minutes.
Resistance standards for compressors refrigerators
There are no universal resistance values for all compressors - they depend on the model, power and even the year of manufacture of the equipment. However, there are Mid rangesthat you can focus on:
| Winding type | Normal resistance (Ohm) | Notes |
|---|---|---|
| Operating (R → S) | 10–40 Ohm | The more powerful the compressor, the lower the resistance (for example, for Danfoss it is closer to 10–15 Ohms, for low-power ones - to 30–40). |
| Starting (S → C) | 20–60 Ohm | Always higher than the working one. If the difference is less than 10 Ohms, interturn breakdown is possible. |
| Total (R → C) | 30–100 Ohms | Sum of resistance of the working and starting windings (checked to confirm serviceability). |
For accurate diagnostics, it is better to find the passport data of a specific model. For example, for compressors Embraco series EG the working winding usually shows 12-18 Ohms, and the starting winding - 25-35 Ohms. V Secop (Danfoss) values may be lower: 8–12 Ohms and 18–25 Ohms, respectively. If your refrigerator is older than 10 years, deviations of up to 10–15% from the norm are allowed due to natural wear and tear of the windings.
How to measure the resistance of a compressor with a multimeter: step-by-step instructions
For To check, you will need multimeter (even a budget model for 300–500 rubles will do) and a screwdriver. Follow the algorithm:
- Disconnect the refrigerator from the mains and wait until the capacitors are discharged (5-10 minutes).
- Remove the protective cover from the compressor (usually it is secured with 1-2 screws). Under it you will see 3 contacts, marked with letters:
R(Run) - working winding,S(Start) - starting winding,C(Common) - common contact.
- Move the multimeter to resistance measurement mode (Ω) for a range of 200 Ohms.
- Measure the resistance between pairs of contacts:
R → S(working winding),S → C(start winding),R → C(total).
Disconnect the refrigerator from the outlet
Wait 10 minutes for the capacitors to discharge
Remove the protective cover from the compressor
Check the integrity of the wire insulation
Set the multimeter to 200 Ω-->
If the multimeter screen displays 0 or 1 (infinity), this means break or short circuit. If the values are normal, but the compressor does not start, the problem may lie in the start relay or capacitor - they should also be checked. Please note: some modern models (for example LG Inverter) have compressors that are electronically controlled, and their diagnosis requires special equipment.
What to do if the contact markings are erased?
If the letters R, S, C are not readable, focus on the location:
- Leftmost contact - usually R (working),
- Rightmost - C (general),
- Central — S (start-up).
To be sure, check the photographs of the compressor of your model on the Internet or look at the diagram on the housing sticker (if it is preserved).
Typical resistance faults and their causes
Deviations from the resistance standard are a symptom, not a diagnosis. Let's figure out what they mean in practice:
- 🔌 Resistance 0 Ohm between any contacts —short circuit. Most often it occurs due to overheating of the windings (for example, if the refrigerator worked without a break in the heat) or mechanical damage to the insulation.
- 🚫 Resistance tends to infinity (break) —open circuit. Reasons: corrosion of contacts, physical wear of wires or damage during transportation.
- ⚡ The resistance of the starting winding is equal to the resistance of the working winding - interturn short circuit. The compressor can start, but it will heat up and quickly fail.
- 🔄 The resistance “floats” during repeated measurements —unstable contact or oxidation of the terminals. Try to clean the contacts and repeat the measurement.
If the compressor hums, but does not start, and the resistance is normal, starting relay or capacitoris to blame. In inverter models (Samsung Digital Inverter, LG Smart Inverter), the problem may lie in the control board - its diagnosis requires an oscilloscope.
⚠️ Attention: If the compressor is “stuck” (the shaft does not rotate), do not try start it forcibly - this can lead to breakage of the windings or damage to the valves. In this case, the part must be replaced.
Resistance of compressors of popular brands: table of values
Below we give approximate values for refrigerator compressors of different brands. Please note that the data may vary depending on the model and year of manufacture:
| Refrigerator brand | Compressor model | Working winding (R→S), Ohm | Starting winding (S→C), Ohm | Total (R→C), Ohm |
|---|---|---|---|---|
| Atlant | Danfoss NL10 | 12–15 | 20–25 | 32–40 |
| Indesit, Ariston | Embraco EG80 | 15–18 | 25–30 | 40–48 |
| Samsung (inverter) | Samsung Digital Inverter | 8–12 | 15–20 | 23–32 |
| LG | LG Linear Compressor | 10–14 | 18–22 | 28–36 |
| Bosh, Siemens | Secop (Danfoss) SC15 | 9–12 | 16–20 | 25–32 |
If your model is not in the table, look for the data on the compressor nameplate (usually the model and technical parameters are indicated there) or use online catalogs of manufacturers, for example Embraco or Secop.
⚠️ Attention: For refrigerators with a system No Frost compressors are often paired with fans, and their resistance may differ slightly from standard values due to the additional load.
What to do if the resistance does not match normal
If measurements show deviations, act according to the situation:
- 🔧 Short circuit or break —the compressor must be replaced. Repairing the windings at home is impossible (rewinding is required on a special machine).
- 🔄 Interturn short circuit - if the compressor still starts, you can temporarily operate the refrigerator, but get ready for replacement in the coming months.
- 🛠️ Oxidation of contacts —clean the terminals with sandpaper and repeat the measurement. If the resistance is normalized, the problem is solved.
- 🔌 Problems with the starting relay - check the relay with a tester (coil resistance should be 50–200 Ohms). If there is a malfunction, replace it.
If you are not confident in your abilities, contact a specialist. Replacing a compressor is a labor-intensive process that requires evacuation of the system and refilling with freon. Cost of a new compressor varies from 3,000 to 15,000 rubles depending on the model, and the work of a master will cost 2,000–5,000 rubles. For refrigerators older than 10 years, it is sometimes more advisable to buy new equipment.
Common mistakes when checking resistance
Even experienced craftsmen sometimes make mistakes that distort measurement results. Here's what you shouldn't do:
- ❌ Measure resistance with the compressor turned on —this is dangerous and pointless (the multimeter will show voltage, not resistance).
- ❌ Ignore discharge capacitors —residual charge can damage the multimeter or give false readings.
- ❌ Confusing contacts —if you confuse
RandS, you will receive incorrect data and may mistakenly diagnose a fault. - ❌ Use a faulty multimeter —before measuring, check the tester on a known resistor (for example, 100 Ohms).
Another common mistake is do not take into account the compressor temperature. The resistance of the windings depends on their heating: for a cold motor it will be higher, for a hot motor it will be lower. For accuracy, take measurements at room temperature (20–25°C), when the compressor has cooled down after operation.
1. Start relay (does it click when turned on?).
2. Capacitor (its capacity must correspond to the passport value).
3. Pressure in the system (if freon leaks, the engine will hum, but will not start).-->
FAQ: Frequently asked questions about compressor resistance
Is it possible to check the compressor without a multimeter?
Indirectly - yes. If the compressor does not start, but is humming, try lightly tapping the housing with a screwdriver (sometimes this helps to “move” the jammed shaft). If the motor is silent, check for voltage at the relay terminals. However, without measuring the resistance, you will not know whether the windings are working properly.
Why is the resistance of the starting winding higher than the working winding?
The starting winding has more turns of thin wire, so its resistance is higher. It is needed only for the initial “push” of the rotor. After the engine starts, the relay turns off, and only the working winding works.
What to do if the resistance is normal, but the refrigerator does not freeze?
Check:
- Freon leakage (pipes in oil, freezing in unintended places).
- Clogged capillary tube (the compressor is hot, but the condenser is cold).
- Thermostat or electronic control unit (if the motor does not turn on at all).
Which multimeter is better to use?
Any digital tester with a mode for measuring resistance up to 200 Ohms will do. Popular models: DT-830B, Mastech MS8229, UNI-T UT33D. The main thing is that the device is in good working order and shows accurate values (check with a reference resistor).
Is it possible to repair a compressor with a broken winding?
At home - no. Rewinding windings requires special equipment and skills. Workshops rarely offer such services, since the cost of repairs is comparable to the price of a new compressor. The exception is antique refrigerators, where spare parts are not available.