A sudden stop of the refrigeration unit or, conversely, its continuous operation without reaching the set temperature is always a signal of possible problems in the system. The central element that ensures the circulation of the refrigerant is compressorwhich is often called the “heart” of the device. It is on its serviceability that it depends whether the necessary cold will be maintained in the chambers or the products will begin to deteriorate.
Before calling a technician or taking the equipment to a service center, it is important to carry out an initial diagnosis in order to understand the scale of the problem. Many owners mistakenly believe that sophisticated factory equipment is required to check an electric motor, but there are proven methods for assessing the condition of the unit using a minimal set of tools. A correct understanding of the principles of operation will allow you to save time and money on calling a specialist for simple cases.
In this article we will analyze in detail the algorithm of actions for identifying motor malfunctions, consider ways to measure electrical parameters and learn how to distinguish a compressor breakdown from problems with a thermostat or start relay. Carefully follow the instructions will help you make an informed decision on further repairs.
Primary diagnosis without disassembly and tools
The very first stage of testing does not require any technical devices other than your hearing and tactile sensations. Go to a working (or trying to work) refrigerator and listen. A working unit emits a uniform, low-frequency hum. If you hear clicks, a hum that ends abruptly, or complete silence when plugged into the network, these are the first signs of trouble.
Pay attention to the temperature conditions of the case. During operation, the side walls and rear grille of the condenser should be evenly heated. If the compressor hums, but no heat is generated, or only the motor itself heats up and the tubes remain cold, this may indicate an interturn short circuit or a wedge in the piston group. Tactile diagnostics often provides more information than a visual inspection.
⚠️ Attention: If you smell burning wiring or see sparking in the area of the start relay, immediately unplug the refrigerator. Further operation in this condition may lead to a fire or complete failure of the apartment's electrical network.
It is also worth checking the vibration of the housing. Excessive shaking may indicate an unbalanced motor mount or internal problems with the compressor suspension. However, slight vibration at the time of starting and stopping is an absolutely normal physical process for most models. without interruption Indesit And Atlant.
Visual inspection and check of the start relay
If the initial inspection did not give a clear answer, you need to move on to a more detailed study of the back of the refrigerator. To do this, the unit must be moved away from the wall and access to the compressor compartment must be provided. Be sure to disconnect the device from the power supply before starting any manipulations with wires and parts.
Remove the protective cover covering the compressor and inspect the start relay. This is a small box placed on the motor contact rod. Often it is the failure of this inexpensive element that creates the illusion of a breakdown of the engine itself. Carefully disconnect the relay and shake it: if a ringing or knocking sound is heard inside, it means that the internals are damaged and require replacement.
- 🔍 Inspect the contacts for oxidation, carbon deposits or melted insulation.
- 🔍 Check the integrity of the wires going to the terminal block for kinks.
- 🔍 Make sure that there are no oil smudges on the compressor housing, indicating depressurization.
Pay special attention to the condition of the windings, if they are visible. Blackening or swelling of the insulation is a sure sign of overheating. In some models, for example LG or Samsung, the relay can be integrated into an electronic board, which requires more complex diagnostics. If no visual defects are found, we proceed to measurements.
Necessary tools for an accurate check
To carry out high-quality diagnostics, you will need a basic kit for a home craftsman. The main tool will be multimeter (or tester), which allows you to measure the resistance and integrity of the circuit. Without this device, the check will be only approximate.
You may also need pliers, screwdrivers (Phillips and flathead) for removing the casings, and possibly electrical tape for marking the wires. If you plan to check the pressure in the system (which is rarely done and only by professionals), you will need a pressure gauge station, but for checking the engine at home it is usually not needed.
| Tool | Purpose | Importance |
|---|---|---|
| Multimeter | Measuring winding resistance | Critically important |
| Screwdrivers | Disassembling the housing and relay | High |
| Pliers | Removing terminals | Medium |
| Insulating tape | Marking of contacts | Recommended |
Make sure that the multimeter probes are in good working order and the battery is in the device not discharged, otherwise the readings may be incorrect. To check for breakdown of the housing, it is also advisable to have a test lamp on hand, although a modern digital tester can often cope with this task.
Measuring the resistance of the windings with a multimeter
This is the most accurate way to determine the condition of the electric motor. After removing the start relay, you will see three or four leads coming from the compressor. They are usually designated by letters or color, but it is better to focus on their location according to the diagram for your model.
Switch the multimeter to resistance measurement mode (Ohm). First check the integrity of each winding separately. One probe is placed on the common wire, the second on the starting winding, then on the working winding. Normal resistance values vary depending on the power of the motor, but usually range from 10 to 50 Ohms for the starting winding and less for the working one.
Normal resistance values
For most household refrigerators, the resistance of the starting winding is higher than the working one. If the device shows infinity (open circuit) or zero (short circuit), the compressor is faulty.
A critically important step is checking for a “breakdown” of the mass. To do this, one multimeter probe is applied to any winding contact, and the second is applied to a place on the metal body of the compressor that has been cleared of paint. The device should show infinity (one or OL on the screen). Any other values indicate that the current is flowing to the housing, which is deadly and requires replacement of the unit.
- 🛠 If there is resistance between the windings and the housing, the motor has burned out.
- 🛠 If the resistance of one of the windings is very different from norms - interturn short circuit.
- 🛠 If the circuit does not ring at all - internal wire break.
It is worth noting that for inverter compressors, which are found in modern models Bosch or Haier, the procedure may differ due to the presence built-in electronics. In such cases, the standard dialing may not be informative.
⚠️ Attention: Never carry out resistance measurements until the capacitors in the circuit are discharged, or while the device is connected to the network. This can lead to failure of the multimeter itself and electric shock.
Checking for interturn short circuit with current clamps
There are situations when the resistance of the windings is normal, the engine starts, but the refrigerator does not freeze or the circuit breaker knocks out after some time of operation. This may indicate turn-to-turn short circuitwhich is not always visible during static measurement with an Ohmmeter.
For such diagnostics, it is best to use current clamps. They allow you to measure the current consumed by the compressor in operating mode without breaking the circuit. The normal current for household refrigerators is usually in the range from 0.3 to 0.8 Amperes, depending on the model and volume of the chambers.
Start the refrigerator and wrap one of the compressor power wires (usually phase) with pliers. If the readings significantly exceed the nominal values indicated on the unit nameplate, it means that there are short-circuited turns in the windings. In this case, the engine operates with overload, heats up and will soon be switched off by a thermal relay.
It is also worth observing the behavior of the arrow or numbers on the device at the time of startup. A sharp jump that does not drop to operating values indicates that it is difficult for the motor to turn over, which may be due to both electrical and mechanical jamming.
Diagnostics of mechanical faults and wedge
If the electrical part is in order, but the compressor hums and does not start (or starts for a split second), there is a high probability of a mechanical wedge. The piston group could be stuck due to thickened oil, depletion of service life, or foreign particles entering the system.
There is a “wedging” method, which sometimes helps to revive the unit, although it is considered a temporary measure. The essence of the method is to apply voltage directly to the working winding, bypassing the starting relay, often using a button or starting device. This creates a powerful starting moment that can break a jammed piston.
However, this method requires caution and an understanding of the risks. If the compressor operates on a hydraulic wedge (filled with liquid freon), such a procedure can completely destroy the valves. Therefore, before attempting to start, you need to make sure that there is no excess liquid in the system.
☑️ Fault finding algorithm
If the motor starts working after an attempt to wedge, it can work for several more years, but most often this is a signal for an early replacement. Mechanical wear of the rubbing parts has already occurred, and a repetition of the situation is only a matter of time.
Frequent errors during self-checking
Home craftsmen often make mistakes that lead to false conclusions. One of the most common is trying to test the compressor without turning off the thermostat or defrost sensor. In this case, the motor may not start simply because the system “thinks” that the temperature has already been reached.
Another mistake is ignoring the state of the capacitor (if it is in the start circuit). A failed capacitor will not allow the engine to develop the required speed, and the user will decide that the compressor itself has broken down. Always check the entire chain of components, and not just the main unit.
- ❌ Measuring resistance with dirty or wet hands (distortion of readings).
- ❌ Trying to start the compressor without freon (leads to overheating).
- ❌ Ignoring the burning smell at the first signs of a malfunction.
Also, you should not rely on only one diagnostic method. An integrated approach, including visual inspection, resistance measurements and analysis of operation under load, gives the most accurate picture of the condition of the equipment.
Is it possible to check a compressor without a multimeter?
Completely - no. Without a measuring device, you can only indirectly judge the malfunction by the lack of cold, overheating of the case or the nature of the sound. However, it is impossible to determine the exact cause (break, breakdown, short circuit) without a tester.
What to do if the compressor is hot, but does not work?
A hot case with the motor not working often indicates a thermal breakdown or internal protection has tripped. Allow the refrigerator to cool down (4-6 hours). If after switching on the situation repeats, most likely, you will need to replace the compressor or start relay.
How much does it cost to replace a compressor in the service?
The cost consists of the price of the new unit and the work of the technician. On average, replacement costs 40-60% of the cost of a new refrigerator. If the equipment is more than 7-10 years old, it is often more advisable to buy a new device than to repair the old one.
Why may a new compressor not start?
The reasons may be low voltage in the network, a malfunction of the starting relay, which was not replaced along with the motor, or the absence of freon (if the system was depressurized). It is also important to check whether the tubes are jammed during installation.