A sudden stop of the refrigerator often becomes an unpleasant surprise, especially when there are perishable foods inside. In most cases, the cause of the malfunction is the heart of the cooling system, which stops starting or works intermittently. Before calling a technician, you should try to diagnose the problem yourself, since in many cases the breakdown turns out to be less serious than it seems at first glance. compressor - the heart of the cooling system, which stops starting or works intermittently. Before calling a technician, you should try to diagnose the problem yourself, since in many cases the breakdown turns out to be less serious than it seems at first glance.
Modern technologies make it possible to carry out an initial check without complex equipment, using only basic tools and visual inspection. It is important to understand that motor-compressor this is a sealed unit, and if it really fails mechanically, repairs will require professional soldering and replacement of freon. However, before deciding on an expensive replacement, it is necessary to exclude electrical faults, such as broken windings or problems with the start-up relay.
In this article we will look in detail at how to check the compressor in a refrigerator using a multimeter and visual methods, and will also provide video materials for clarity. If the compressor hums, but does not start, or does not make any sounds at all, these are the first signals for diagnostics. Correctly determining the cause of the breakdown will help save budget and time.
Primary diagnostics: visual inspection and sound analysis
The first stage of any repair is thorough external inspection and analysis of equipment behavior. If you hear your refrigerator trying to start, making a clicking sound, and then silence, this could indicate a faulty start relay or a locked compressor. In some cases start relay it simply sticks, and light tapping may temporarily solve the problem, but this is only an indirect sign.
Pay attention to the temperature of the compressor housing. If the motor is hot but the refrigerator is not cooling, it may be overheating due to prolonged operation or poor ventilation. It is also worth inspecting the tubes for oil stains: the presence of oil at the base of the tubes often indicates depressurization of the system, which makes further checking of the electronics pointless.
⚠️ Attention! If you notice a strong burning smell or visible traces of melted wires, immediately unplug the refrigerator. Further operation may result in a fire.
For a deeper understanding of sound signals, it is useful to refer to reference materials. Below is a table to help classify symptoms.
| Sound / Symptom | Probable cause | Required actions |
|---|---|---|
| Silence, no hum | Open circuit, faulty relay or thermostat | Checking voltage and continuity of windings |
| Humming and clicking | Piston group jammed or relay malfunction | Replacing the start relay, checking the compressor |
| Continuous operation without shutdown | Freon leak or compressor wear | Searching for leaks, checking pressure |
| Knock and vibration | Destruction of the internal motor mount | Replacing the compressor |
Understanding these basic signs allows you to weed out up to 30% of false alarms associated with thermostat settings or overloading the chamber with products.
Preparation for testing: tools and safety
Before you begin directly checking the electrical part, it is necessary to ensure safe working conditions. You will need multimeter (tester), screwdrivers to remove the casing and possibly pliers. The main rule is that all work to open the electrical compartment is carried out only with the device completely disconnected from the network.
Remove the rear protective panel of the refrigerator to gain access to the compressor. At the bottom of the motor you will see a plastic box - this is the casing of the start-up relay. Carefully remove it by unclipping the retaining clips. Inside you will see the wires going to the compressor contacts, and the relay itself.
☑️ Preparation for diagnostics
Before starting measurements, make sure that there are no oxides or carbon deposits on the contacts. If the relay contacts are blackened, this may be the cause of poor contact, but most often it is the motor itself that needs to be checked. Also check the integrity of the supply wires: they should not be frayed or melted.
To work with a multimeter, switch it to the resistance measurement mode (Ohms), usually in the range of 200 Ohms or 2 kOhms. Make sure that the probes are in good condition by shorting them to each other: the device should show zero or a value close to it.
Checking the motor windings with a multimeter
The most reliable way to determine the condition of the electric motor is to ring its windings. There are usually three contacts on the compressor housing, covered with a cover or located under the relay. Remove the start relay and protective plate to gain access to the three triangle-shaped terminals.
The contacts are designated as C (Common), S (Start - start winding) and R (Run - run winding). Sometimes the markings are missing, so it is important to identify them correctly. The resistance between the common contact and the working winding is usually less than that between the common and the starting winding. Between the starting and working windings, the resistance should be the sum of the two previous values.
Take measurements by applying multimeter probes to pairs of contacts:
- 🔌 General - Working: there should be the lowest resistance (usually 10-30 Ohms).
- 🔌 General - Starting: resistance is higher (usually 30-50 Ohms).
- 🔌 Starting - Working: the sum of the two previous values.
What to do if the readings are they different?
If the resistance tends to infinity, the winding is broken. If it goes to zero, there is a short circuit. In both cases, the compressor requires replacement.
If the multimeter shows one (infinity) in any of the sections, it means that something has happened winding break. If the device shows zero or a very small value, it has happened short circuit. In both cases, repairing the compressor at home is impossible; replacement of the unit is required.
It is also necessary to check the breakdown on the housing. Touch one probe to any contact, and the other to the stripped metal part of the compressor housing (where there is no paint). The device should not respond. The appearance of resistance indicates an insulation breakdown, which is life-threatening.
Diagnostics of the starting relay and thermal protection
Often the compressor itself is working, but cannot start due to a faulty starting relay. This device applies an impulse to the starting winding to spin the motor shaft. Inside the relay there is a coil and contacts that can burn or stick over time.
Carefully remove the relay from the casing. Visually inspect it for cracks or signs of burning. Shake the relay: if something rattles inside, it means the mechanism is destroyed. Check the integrity of the relay coil with a multimeter: the resistance should be within normal limits (usually several tens of Ohms), and not go to infinity.
Thermal protection, which is often built into the relay or located nearby, also needs to be checked. It opens the circuit when it overheats. Ring it: when cold, it should “ring” (show zero). If the thermal protection does not pass current, the motor will not receive power.
Sometimes temporarily removing the relay from the circuit for testing (direct connection) helps, but this is dangerous and requires skills. It is better to replace the relay with a known good one of the same marking. The marking is usually applied to the body, for example PZR or PTC.
⚠️ Attention! Direct connection of the compressor, bypassing the relay, is allowed only for a short time (seconds) for diagnostics. Long-term operation without a relay will lead to burnout of the windings.
How to check the compressor without removing it from the refrigerator
In some cases, especially in models with a bottom-mounted compressor, access to the contacts is difficult, but you can check the presence of voltage without complete disassembly. To do this, you will need to measure the voltage at the input to the start relay at the moment when the thermostat requires turning on.
Plug in the refrigerator and set the thermostat to maximum cooling. At the moment when the start-up should occur, carefully (observing safety precautions!) Measure the voltage on the contacts going to the relay. The presence of 220 Volts indicates that the circuit to the compressor is intact, and the problem is either in the relay or in the motor itself.
If there is no voltage, the problem may be in the thermostat, defrost sensor or electronic control module. In modern models, diagnosis is more difficult, since they operate on direct current and are controlled by complex electronics. Checking such motors with a conventional multimeter often does not give a complete picture. inverter compressor diagnostics are more difficult since they operate on direct current and are controlled by complex electronics. Testing such motors with a conventional multimeter often does not give the full picture.
For inverter systems, it is important to check not only the presence of voltage, but also its stability. Voltage surges can prevent starting. In such cases, it is often necessary to replace the control board, and not the compressor itself.
Typical diagnostic errors and their consequences
One of the most common mistakes is an attempt to start a “jammed” compressor by applying increased voltage or striking the housing. This can lead to the final destruction of internal mechanical parts and depressurization of the system, which will make repairs economically unfeasible.
Also, beginners often confuse a broken winding with a thermostat malfunction. If the thermostat does not close the circuit, the compressor will not receive power, and the user may mistakenly believe that the motor has burned out. Always start by checking the power circuit.
Do not forget about the capacitor (if there is one in the circuit). In some models, the starting capacitor may swell or lose capacity, which will prevent the motor from developing the required speed. Testing the capacitor requires a special device or careful discharge and testing with a spark (the method is dangerous and not recommended).
⚠️ Attention! Technical characteristics of compressors of different brands (Indesit, LG, Bosch) may differ. Always check the technical documentation for your specific model before replacing parts.
Correct diagnosis requires composure and consistency. Do not rush to buy a new compressor until you are 100% sure that it is faulty.
FAQ: Frequently asked questions
Is it possible to repair a burnt-out compressor yourself?
No, a compressor is a sealed unit filled with refrigerant under pressure. Opening requires special equipment for pumping out freon, soldering and vacuuming the system. It is impossible and dangerous to do this at home.
Why does the compressor hum but does not start?
Most often this indicates a malfunction of the starting relay, which cannot supply a pulse to the starting winding. The second reason is a mechanical wedge of the piston group or a voltage drop in the network.
How to find out which compressor is needed for replacement?
On the body of the old compressor there is a sticker or nameplate with the model (for example, ACC GT10LA or Secop NL11FT). The selection is made by performance (W) and type of refrigerant (R134a, R600a).
Is it dangerous to touch the compressor during operation?
Yes, the housing can heat up to 70-90 degrees Celsius. In addition, if there is an insulation breakdown, dangerous voltage may be present on the housing. Always disconnect the device from the network before touching the internal elements.
How much does it cost to replace a compressor?
The cost consists of the price of the unit itself (from 5 to 15 thousand rubles) and the cost of the work of the technician, taking into account refilling with freon. On average, replacement costs 10-20 thousand rubles, depending on the refrigerator model.