A sudden stop of the refrigerator or, conversely, its continuous operation without reaching the set temperature are alarm signals that cannot be ignored. Most often, the source of the problem is the heart of the unit the motor-compressor responsible for circulating the refrigerant in the system. It is on its serviceability that it depends whether there will be ice in your freezer, or whether the food will quickly deteriorate.
Before calling a technician or rushing to the store for new equipment, it is worth conducting an initial diagnosis. Understanding how to check a refrigerator compressorwill allow you to save significant money on false repairs or accurately formulate the problem to a specialist. In this article we will analyze all stages of testing: from visual inspection to complex measurements of electrical parameters.
It is worth noting that modern inverter models Bosch or LG can behave differently than classic linear compressors of Soviet "Samsung" or "Atlant". However, the basic principles of physics remain the same: if the engine does not produce pressure or does not start, the system does not work. Your task is to localize the malfunction.
Visual diagnostics and primary signs of malfunction
Any in-depth diagnostics begins with an external examination. Often signs that the compressor does not workare visible to the naked eye or audible without the use of instruments. First of all, pay attention to the behavior of the unit itself: does it turn on at all, or is there silence in the entire kitchen.
If you hear a characteristic click, followed by a hum that lasts a few seconds, and then again a click and silence, this is a sure sign that start relay is trying to start the engine, but can't. This situation often indicates jamming of the piston group or interturn short circuit of the windings. In some cases, the compressor housing itself may be hot to the touch, which indicates overheating.
⚠️ Attention: If you notice oily spots or smudges on the back wall of the refrigerator, this may indicate a depressurization of the system or an oil leak from the compressor crankcase. Operation of such a unit is prohibited.
It is also important to check the integrity of the electrical cable and plug. Sometimes the problem lies simply in poor contact in the socket or damage to the power cord, which is why motor-compressor simply does not receive energy. Make sure that the thermostat is set to the correct position and is not in the “Off” mode.
Symptoms indicating a motor breakdown
There are a number of specific symptoms that are highly likely to indicate problems with the compressor unit, and not with other components of the refrigerator. Understanding these signs helps to weed out false diagnoses associated, for example, with a freon leak or a clogged capillary.
One of the most obvious symptoms is lack of cooling with the engine running. If the compressor hums continuously, without turning off for hours, but the temperature in the chambers does not drop, this may indicate a loss of compression. The pistons wear out, the valves burn out, and the device simply circulates gas in a circle without creating the necessary pressure.
- 🔊 A loud metallic knock or clanging sound when starting is a sign of destruction of internal mechanical components.
- 🔥 Excessive heating of the housing compressor (it is impossible to hold your hand for more than 2-3 seconds) indicates an overload.
- 💡 A flashing light on the control panel (for models Indesit or Atlant) often indicates a failure in the motor circuit.
- ❄️ The formation of a “fur coat” in only one corner of the freezer while the motor is running may be a sign of a partial loss of performance.
It is important to distinguish between compressor noise and fan noise (in No Frost systems). If you turn off the fan, but the sound remains, it means that the source of vibration is itself unit. It is also worth listening to the nature of the sound: a steady hum is normal, intermittent or howling is not.
Instrumental check: multimeter and resistance
For a more accurate diagnosis you will need multimeter. This device will allow you to measure the resistance of the motor windings and identify breaks or short circuits. Before starting any work on electrical components, the refrigerator must be unplugged!
Remove the protective casing from the back of the compressor to gain access to the contacts of the start relay and the motor itself. Typically there is a terminal block with three or four pins. You need to “ring” each winding by switching the multimeter to the resistance measurement mode (Ohm).
Normal winding resistance values:- Starting winding: 20-40 Ohm
- Operating winding: 10-15 Ohm
- General winding: the sum of values or less than the working one
If the device shows infinity (one in the most significant digit), it means in the winding break. If the resistance is close to zero, it happened short circuit. In both cases, the compressor must be replaced, since rewinding at home is impossible and economically unfeasible.
☑️ Check with a multimeter
It is also worth checking the resistance between the terminals and the compressor housing (on "breakdown") One probe is placed on a copper fitting or an unpainted part of the body, the other is placed on each contact in turn. Infinitely high resistance is considered the norm; any readings in Ohms indicate an insulation breakdown and the danger of electric shock.
Checking the starting relay and capacitor
Often the compressor itself is working, but cannot start due to the failure of the starting equipment. Starting relay - this is a small block that is put on the contacts of the compressor. Inside it there is a coil and a movable core, which close the circuit of the starting winding at the moment of start.
To check the relay, it must be carefully removed. If it is an electromagnetic relay, shake it: if you hear the ringing of broken parts inside, it means the mechanism is destroyed. Thermal relays are checked for resistance: in a cold state it should be close to zero, when heated (if it is possible to heat it carefully) it should open.
| Relay type | Symptom of serviceability | Symptom of malfunction | Action |
|---|---|---|---|
| Electromagnetic | No ringing when shaking | Ringing, carbon deposits on contacts | Replacement |
| Thermal | Resistance ~0 Ohm | Resistance is infinite | Replacement |
| Posistor | Integrity of ceramic element | Cracks, chips | Replacement |
| Capacitor | No swelling | Bloating, electrolyte drips | Replacement |
Some models of refrigerators, especially old or industrial ones, use starting capacitors. They help create a phase shift to start the engine. A swollen or “leaking” capacitor must be replaced with a similar capacitance and voltage.
⚠️ Attention: When replacing the starting relay, strictly follow the “Top” marking or arrow on the case. Installing the relay upside down will make it impossible to start or burn out the windings.
Diagnostics of pressure and performance
If the electrical part is in order, but there is no cold, you need to check compression the ability of the compressor to build up pressure. This will require a pressure gauge station, but there is also a “folk” method that requires caution.
The essence of the method is to disconnect the capillary tube from the discharge pipe of the compressor. When turned on, a working unit should blow out air forcefully. If the air flow is barely felt or is not there at all, it means that the valve group inside the compressor does not hold pressure.
Technical nuances of checking pressure
For accurate diagnosis, professionals connect a pressure gauge to the service fitting. Normal discharge pressure for household refrigerants (R134a, R600a) statically depends on temperature, but should increase during operation. If the pressure gauge needle stands still or grows extremely slowly, the compressor has “died” mechanically.
It is also worth checking the suction pipe. When a working refrigerator is operating, it should be cold, but not covered with frost, all the way to the compressor. If the entire return pipe is frosted, it is possible that moisture has entered the system or a micro-leak has occurred, which causes the compressor to operate in emergency mode.
Remember that leakage when checking pressure in systems with refrigerant R600a (isobutane) is dangerous. This gas is explosive when concentrated in air. If you hear the hissing of gas, stop work immediately and ventilate the room.
Specifics of diagnostics of inverter compressors
Modern refrigerators LG, Samsung, Bosch increasingly equipped inverter compressors. Checking them with a standard multimeter often gives false results, since the resistance of their windings can be very low, and control occurs with complex pulse signals.
In such systems, there is an inverter module between the compressor and the control board. If the refrigerator does not start, first of all you need to check the presence of voltage at the input to this module. Often it is the inverter board that fails, but the motor itself remains intact.
Inverter motors start smoothly, without the characteristic click of a relay. If you hear clicking noises from your inverter refrigerator, this is most likely the thermal protection relay operating, indicating a malfunction. Diagnostics of such systems requires deep knowledge of electronics.
When a compressor replacement is necessary
The decision to replace is made when a break or short circuit of the windings, mechanical wear of the piston group (lack of compression) or a serious breakdown in the housing is detected. Repairing the compressor “pot” itself is impossible at home.
The replacement process involves not only dismantling the old and installing a new unit, but also soldering copper tubes, evacuation of the system and charging with refrigerant. This requires special tools: a burner, a vacuum pump and freon scales.
If you do not have the skills to work with copper and refrigerants, it is better to stop at this stage. An independent attempt at soldering may lead to a fire (especially with R600a gas) or damage to the new compressor due to moisture in the system.
⚠️ Attention: When replacing the compressor, be sure to change the filter drier. The old filter could be saturated with moisture and acid, which will quickly kill the new expensive unit.
Frequently asked questions (FAQ)
Is it possible to repair the refrigerator compressor yourself?
You can replace the starting relay or capacitor yourself. However, opening the compressor housing, replacing valves or rewinding the motor requires factory equipment and vacuum-clean conditions. It is impossible to do this at home.
Why does the compressor turn on and off immediately?
This phenomenon is called “clocking”. Reasons: the starting relay is faulty (does not start the motor), the compressor is jammed (the motor cannot turn over) or the thermal protection is triggered due to an interturn short circuit.
How much does it cost to replace a compressor?
The cost consists of the price of the unit itself (which can vary from 3 to 10 thousand rubles and above) and the cost of the technician’s work, taking into account travel and materials (freon, filter). You need to find out the exact price from service centers.
Does a working compressor hum?
Yes, a working compressor makes a smooth, monotonous hum. The volume depends on the model. However, sharp knocks, clanging, whistling or intermittent hum with pauses indicate a malfunction.