How to check the Atlant refrigerator compressor with a multimeter

Modern refrigerator Atlant is a complex electromechanical a device where the compressor is the core of the entire cooling system. It is this unit that is responsible for the circulation of the refrigerant, creating the necessary pressure in the circuits. If yours stops freezing, makes strange sounds, or doesn’t turn on at all, the initial diagnosis often comes down to checking this particular unit. Understanding the principles of engine operation allows the owner to independently identify a number of common faults, without resorting to an expensive call to a technician for an initial inspection.

The main tool for carrying out such diagnostics is a conventional digital multimeter. With its help, you can measure the electrical resistance of the stator windings, check for a short circuit to the housing and evaluate the condition of the starting-protective relay. Many users mistakenly believe that failure to start the motor always means its complete failure, but often the problem lies in an open circuit or insulation breakdown, which is easily detected by a measuring device. In this article, we will analyze in detail the algorithm of actions that will allow you to accurately determine the technical condition of the compressor in Belarusian-made refrigerators.

Preparation of the workplace and safety measures

Before starting any work related to electrical components, it is necessary to completely de-energize the household appliance. Unplug the power cord from the outlet and make sure there is no voltage at the terminals. Access to the compressor is usually located in the lower rear part of the housing, where the niche with the unit is located. You will need to remove the protective plastic cover, which is often secured with latches or screws, to provide access to the electrical part of the motor.

To carry out high-quality diagnostics, you will need not only a multimeter, but also a set of tools. Be sure to have insulated pliers, a dielectric-handled screwdriver, and perhaps a test cord with a force-start plug (if you're planning a more in-depth test). The workplace should be well lit and the floor dry, as humidity can distort the instrument readings or lead to electric shock.

It is important to visually inspect the compressor for external damage. Look for signs of oil, melted wire insulation, or bulging metal parts. If the case shows obvious signs of overheating or mechanical deformation, further diagnostics may be unsafe. In such cases, it is better to immediately consider replacing the unit, since repairs may not be economically feasible.

⚠️ Attention: It is strictly forbidden to measure resistance or manipulate the wiring while the power cord is connected to the mains. This can lead to failure of the multimeter and serious injury.

Design of the electrical part of the compressor

To correctly interpret the tester readings, you need to understand how the electrical circuit of the engine works. The refrigerator compressor Atlant is equipped with an asynchronous electric motor, which has two main working windings: starting and working. These windings are wound with copper wire on the stator and have different resistances, which is a key point for diagnostics.

The winding contacts are connected to three terminals located on the motor housing under the starting relay. They are usually marked with letters or symbols, but in older models the markings may be missing or worn off. The standard configuration involves a common wire, a starting winding wire, and a working winding wire. Understanding this circuit allows you to correctly connect the multimeter probes to obtain correct data.

The starting relay plays a critical role in starting the motor by supplying a short-term pulse to the starting winding. If the relay is faulty, the compressor may hum but not start, although the engine itself may be completely fine. Therefore, when diagnosing, it is important to separate the concepts: checking the motor itself and checking the control circuit.

How to distinguish windings without a circuit?

If there are no markings, measure the resistance between all three contacts. The greatest value will be between the ends of the starting and working windings. The third contact, which gives average values ​​with these two, is common.

Checking the stator windings for resistance

The very first and informative stage of the test is measuring the active resistance of the windings. Switch the multimeter to resistance measurement mode (limit 2 kOhm or 200 Ohm). Remove the start relay from the compressor terminals to provide direct access to the three motor terminals. Carefully clean the contacts if oxidation is visible on them, as this may affect the accuracy of the measurements.

Sequentially measure the resistance between each pair of contacts. You need to get three values: between the first and second contact, between the second and third, and between the first and third. Normal values ​​for different models Atlant may vary, but usually the resistance of the working winding is 10–30 Ohms, and the starting winding is 20–50 Ohms. The sum of the resistances of the two smaller values ​​should be equal to the largest measured value.

If the device shows one (infinity) in any area, this indicates a winding break. In this case, current cannot flow through the circuit and the engine will not start. If the resistance is close to zero, this indicates an interturn short circuit, which is often accompanied by overheating and knocking out plugs when trying to turn on.

Let's consider typical resistance values for various states of windings in the table below:

⚠️ Attention: The multimeter readings may “float” in the first seconds of measurement due to the capacitance of the windings. Wait until the numbers on the screen stabilize before recording the result.

Diagnostics of breakdown on the housing (interturn short circuit)

One of the most dangerous malfunctions is breakdown of winding insulation on the metal body of the compressor. This situation creates a risk of electric shock when touching the refrigerator and must be corrected immediately. To check, switch the multimeter to the continuity mode or measure resistance to the maximum limit (2 MOhm and higher).

Press one probe to any of the three motor contacts (or to the copper fitting, if the contacts are unavailable, having previously stripped the paint), and attach the second probe to the unpainted metal part of the compressor housing. The ideal indicator is infinity (number 1 on the screen in the left position). If the device shows any resistance value, even a very large one, this indicates an insulation failure.

An interturn short circuit inside the windings is more difficult to identify, since the resistance may change slightly. However, an indirect sign is often strong heating of the case during operation and a constant hum. If you find a breakdown in the housing, operation of such a refrigerator is strictly prohibited until repair.

Analysis of the start relay and thermal fuse

Often the cause of a non-working compressor is not the motor itself, but the attachment. Start relay in refrigerators Atlant can be electromagnetic or posistor. To check, remove the relay and shake it: if you hear a knock inside, the core or contacts may be broken. In posistor relays, check the resistance of the posistor itself - it should be within tens of Ohms.

Also, the circuit often contains a thermal fuse, which breaks the circuit when the windings overheat. It must be “ringed” with a multimeter in diode or resistance testing mode. The device should show zero or a value close to it. If the circuit does not ring, the fuse is blown and requires replacement. This is a cheap part, but its combustion often indicates that the compressor has previously overheated.

Remember to check the integrity of the supply wires. Vibration during operation of the refrigerator over time breaks the wires inside the insulation, especially at the points where they exit the relay housing. Visual inspection and “probing” the wires will help identify hidden breaks that are not visible from the outside.

Interpretation of results and final conclusions

After all measurements have been carried out, it is necessary to combine the data obtained into a single picture. If the resistance of the windings is normal, there is no breakdown to the housing, and the relay and fuse are working, then most likely the problem is mechanical in nature (the piston is jammed) or is associated with a freon leak. If jammed, the compressor often hums, but the shaft does not rotate.

If a break or short circuit is detected, the compressor must be replaced. Repairing windings in a factory environment is practically impossible and not economically justified. Modern sealed units are not designed for disassembly and rewinding, so replacing with a new analogue is the only correct solution.

Therefore, diagnostics with a multimeter is only the first, albeit very important, stage of troubleshooting. A competent approach allows you to weed out electrical problems and focus on finding other causes.

Is it possible to start a compressor without a relay?

Theoretically, it is possible to apply voltage directly to the working one winding, but this is dangerous and requires special skills. Without a starting winding, the motor will not reach the required speed and may burn out. For short-term testing, technicians use special test cords, but this is not recommended at home.

Why does the multimeter show different resistance values?

The resistance of copper depends on temperature. If the compressor has just been running, the windings are hot and the resistance will be higher. Allow the unit to cool completely (3-4 hours) before measurements to obtain reference data.

What to do if the winding resistances are the same?

In some models of two-phase motors, the resistances of the starting and operating windings may be close, but they are rarely absolutely identical. If the values ​​coincide completely, this may indicate a specific motor design or, more often, an interturn short circuit that has changed the parameters.