A sudden stop of the refrigerator or its inability to maintain the set temperature often causes panic, but in most cases the problem lies precisely in compressor or its control circuits. This unit is the heart of the cooling system, creating the necessary pressure for the circulation of the refrigerant, and its failure paralyzes the operation of the entire unit. Before calling a technician or buying new equipment, it is worth carrying out initial diagnostics to eliminate simple malfunctions.
Modern models of refrigerators, be it Indesit, LG or Atlant, are equipped with different types of engines, but the principles for checking them remain similar. Understanding how the start relay works will allow you to independently determine whether the problem is worth the trouble or whether it is easier to replace the unit. electric motor and a starting relay, will allow you to independently determine whether the game is worth the candle or whether it’s easier to replace the unit.
In this article we will analyze in detail the algorithm of actions, the necessary tools and methods for measuring electrical parameters that will help make an accurate diagnosis. You will learn how to distinguish a burnt winding from a stuck piston and why a humming sound without starting is a serious signal. Let's start studying the design of your refrigeration unit.
External inspection and primary signs of malfunction
The first stage of diagnosis is always a visual analysis and assessment of the behavior of the refrigerator when turned on. Often characteristic sounds or their absence can tell more about the condition compressor than complex devices. If, when you turn on the network, you hear a quiet hum, which after a few seconds is replaced by a click and silence, this indicates an attempt to start and subsequent activation of the thermal protection relay.
Pay attention to the temperature of the motor housing. If the unit hums, but does not start, and the compressor housing itself becomes hot to the point where it is impossible to touch it, this is a sure sign interturn short circuit or mechanical jamming. During normal operation, the engine should be warm, but not scalding. It is also worth inspecting the back wall of the refrigerator for swelling or oily stains, which may indicate depressurization of the system.
⚠️ Attention: If you find traces of oil around the compressor tubes or feel a specific burning smell, immediately disconnect the device from the network. Operation of such a device can lead to a fire or complete failure of the cooling system.
Sometimes the problem lies not in the engine itself, but in the starting relay or thermostat. Check if voltage is being supplied to the terminals. To do this, you can use a simple test lamp or a multimeter in AC voltage measurement mode. The lack of voltage at the inlet to the compressor while the thermostat is running will indicate a problem in the control circuit, and not in the pump itself.
Necessary tools and safety measures
To carry out high-quality diagnostics, you will need a minimum set of tools that most home craftsmen can find. The main device will be multimeter (tester), which allows you to measure the resistance of the windings and check the integrity of the circuit. Without this device, accurate diagnosis of the electrical part of the compressor is almost impossible, since visual signs are often misleading.
You will also need pliers, screwdrivers to remove the protective casing and, possibly, pliers to disconnect the terminals. If you are planning a more in-depth test with a starter relay replacement, make sure you have a suitable replacement with similar specifications. Work should only be carried out with the power supply completely disconnected from the mains.
☑️ Preparation for diagnostics
Remember that refrigerant circulates in the system, which under certain conditions can be flammable or toxic. Although the risk of leakage is minimal when simply checking the contacts, caution is a good idea. Do not try to cut through the tubes or drill into the compressor housing - this is a task for professionals with vacuum equipment.
Removing the casing and checking the start relay
To get to the electrical part, you need to remove the protective plastic or metal casing located at the lower rear of the refrigerator. It is usually secured with latches or screws. After removing the cover, you will see itself compressor black and a box attached to its terminals - this is the starting relay.
Carefully remove the relay from the contacts of the compressor. It can be held on by a bracket or simply sit tightly on the terminals. Inspect the inside of the relay: if you see blackening, melted plastic, or smell a burning smell, then most likely the problem is in this unit. In some cases, it is enough to replace the relay to engine work again.
Check the contacts on the compressor itself. They must be clean, free of oxidation and soot. If the terminals are oxidized, they can be carefully cleaned with fine sandpaper or a file, being careful not to damage the insulation of the suitable wires. Often, poor contact is the reason that the current does not pass to the windings.
How does the starting relay work?
When the refrigerator is turned on, the current passes through the starting winding, creating a magnetic field to start the rotor. As soon as the engine picks up speed, the relay opens the starting winding circuit, and the motor runs only on the working winding. If the relay sticks or does not open, the winding burns out.
Testing the windings with a multimeter
The most reliable way to determine the condition of the electric motor is to measure the resistance of its windings. There are usually three terminals on the compressor housing, forming a triangle. Two of them are responsible for the working winding, one is for the starting winding, and the common wire is zero. For accurate diagnostics, you need to know the connection diagram of your model, for example, Danfoss or Secop.
Switch the multimeter to resistance measurement mode (Ohm) to a limit of 2 kOhm. First, find the common wire (usually it has the least resistance relative to the others). Then measure the resistance between the common wire and the working terminal, as well as between the common and the starting terminal. Normal values may vary, but usually range from 10 to 30 Ohms for the operating winding and slightly higher for the starting winding.
| Measurement type | Normal value | Fault symptom | Probable cause |
|---|---|---|---|
| Working winding | 10 - 35 Ohm | Infinity (1) | Open circuit |
| Starting winding | 20 - 50 Ohm | Zero (0.00) | Short circuit |
| Case and windings | Infinity | Any value | Breakdown to the body |
| Between any terminals | Sum of resistance | Significantly below normal | Interturn short circuit |
If the multimeter shows infinity (one in the most significant digit), then it has occurred in the winding break. If the device shows zero or a value close to it, a short circuit has occurred. In both cases, the compressor must be replaced, since rewinding at home is impossible and economically unfeasible.
⚠️ Attention: When measuring resistance, never touch the metal probes with your hands. This may introduce an error in the measurement due to the resistance of your body, especially if you are checking for leakage to the housing.
Checking for housing breakdown (short to ground)
One of the most dangerous malfunctions is breakdown of winding insulation on the metal body of the compressor. In this case, the refrigerator may work, but touching it becomes deadly. The test is carried out by applying one multimeter probe to a cleaned area on the body (where there is no paint), and applying the second one to the contacts in turn.
With a working engine, the device should show infinite resistance. Any readings, even if the needle moves slightly or the numbers change, indicate a violation of the insulation. Such a compressor must be urgently removed from service. Breakdown on the housing often occurs due to overheating or aging of the varnish insulation of the wires inside the engine.
Sometimes breakdown appears only when heated. If the device shows the norm “in cold conditions”, but knocks out the machine in the panel after 10-15 minutes of operation, this also indicates thermal destruction of the insulation. In such cases, using the device without grounding is strictly prohibited.
Diagnostics of mechanical problems and jamming
The electrical part may be absolutely fine, all windings ring, but the compressor hums and does not start. This indicates a mechanical problem - jamming of the piston group. The reasons may be different: wear of parts, foreign objects entering the system, or thickened oil.
There is a “wedging” method, which sometimes helps to revive the unit. The essence of the method is to apply voltage directly to the working winding, bypassing the starting relay for a short time. This creates a powerful starting torque that can break a jammed piston out of place.
However, this method is risky and requires caution. If after several attempts (no more than 3-4 times for 3-5 seconds) the engine does not start, then the mechanical damage is too serious. Further attempts may lead to the final destruction of the connecting rod or shaft.
It is also worth checking the condition of the oil. If during dismantling you notice that the oil is black and has a burning smell, this indicates overheating and destruction of the rubbing pairs. In this state, the compressor will not work for a long time even after a successful start.
Specifics of diagnostics of inverter compressors
Modern refrigerators are increasingly equipped with inverter compressors that differ in the principle of operation and control. In such models, the engine does not turn off completely, but smoothly changes speed. Checking a conventional linear compressor will not work here, since control is carried out through a complex electronic unit.
Inverter diagnostics require a special tester or oscilloscope to check control signals. A simple continuity test of the windings with a multimeter often shows the norm, even if the compressor is faulty, since the problem may lie in the rotor position sensors or control board.
If you have a refrigerator with an inverter motor and it does not start, first check the connections and the absence of visible damage on the wires. Independent in-depth diagnostics of such systems is difficult without specialized equipment and knowledge of electronics.
⚠️ Attention: Technical characteristics and operating algorithms of inverter systems may differ between different manufacturers. Before intervention, check the technical documentation of the specific model, since incorrect diagnosis can damage the expensive control unit.
Frequently asked questions (FAQ)
Is it possible to replace the compressor yourself?
Theoretically, it is possible, but this requires special equipment: a vacuum pump, a gas station and scales The process includes bleeding out the old freon, soldering the pipes, evacuating the system and charging with new refrigerant. Without experience and tools, it is impossible to perform this work efficiently.
How much does a new compressor cost?
The price depends on the power, manufacturer and type of refrigerator. A regular linear compressor can cost from 3 to 8 thousand rubles. Inverter models are much more expensive - from 10 thousand rubles and above. To this amount you need to add the cost of installation and refueling.
Why does the compressor burn out?
The main reasons: voltage surges in the network, overheating due to contamination of the condenser (radiator at the rear), freon leak (the engine runs without stopping and overheats) or manufacturing defects. Regular cleaning of the rear grill helps prolong the life of the unit.
How to extend the life of the compressor?
Do not place the refrigerator close to the wall, ensure good ventilation at the back. Do not load hot food into the chamber. Make sure that the door seals are in good condition so that the motor does not work non-stop. It is also advisable to use a voltage stabilizer if there are surges in your network.