A sudden increase in temperature in the main chamber or a complete lack of cold often causes panic among owners of household appliances. Before calling a technician or looking for a new unit, it is worth carrying out initial diagnostics to understand where exactly the problem lies. Heart of any refrigeration system there is a compressor, and it is its serviceability that determines whether your refrigerator will work.
If you notice that the motor is humming, but the cold is not coming out, or, conversely, silence in the room is accompanied by defrosting of food, it is necessary to exclude simple causes. In this article, we will look at how to independently determine whether engineis working, whether the starting relay is working properly and whether it is worth undertaking repairs at all.
Often owners confuse the symptoms, believing that the problem is in the refrigerant or thermostat, although in fact the motor could have burned out or the piston may have jammed group. Correct diagnosis at the initial stage will help save time and money, and will also protect you from electric shock during further manipulations.
Primary visual and auditory diagnostics
The first step in determining a malfunction is careful observation of behavior unit. Go to the refrigerator and listen: does it make a characteristic hum, clicks, or operates absolutely silently. The normal condition involves cyclical operation, when periods of silence are followed by the sound of the motor running. If you hear a humming sound, but no cold appears, this may indicate that the compressor is trying to start, but cannot. Often in such cases, a loud click is heard, after which the engine quiets down. This is a classic sign of a faulty start relay or problems with the windings. motor.
If you hear a humming noise but no cold appears, this may indicate that the compressor is trying to start but is unable to. Often in such cases, a loud click is heard, after which the engine quiets down. This is a classic sign of a bad start relay or winding problems.
⚠️ Warning: If you smell a burning smell or see sparking in the rear grille area, immediately unplug the appliance. Further operation may lead to a fire.
It is also worth inspecting the back of the refrigerator. When the compressor is running, the condenser grille (usually black) should heat up evenly. If the motor hums and the pipes remain cold, there may be a freon leak in the system, although the unit itself may be in good working order. clogging there is a freon leak in the system, although the unit itself may be in good working order.
Checking the electrical circuit and voltage
Before getting to the internal components, you need to make sure that The compressor actually receives electricity. To do this, you will need a multimeter configured to measure AC voltage. Be extremely careful, as the work will be carried out under voltage voltage.
Remove the protective cover from the compressor to gain access to the start relay terminals. Carefully disconnect the connector coming from the power cord and check for 220 Volts. If there is no voltage, the problem lies in the wiring, socket or thermostat, and not in the motor itself.
It is also important to check the integrity of the ground wire and the absence of visible damage to the insulation. Oxidized contacts can create high resistance, which is why starting current will be insufficient to start the engine.
Diagnostics of the starting relay and protection
The starting relay is a small block, which is put on the contacts of the compressor. It is he who supplies the impulse to start the winding and turns off the starting circuit after gaining speed. Often it is the failure of this element that simulates the breakdown of the compressor itself. Remove the relay and shake it next to your ear. If a ringing or knocking sound is heard inside, it means that the core or contacts have broken, and the part requires replacement. Also inspect the insides for burning or melting of the plastic. compressor.
Remove the relay and shake it near your ear. If a ringing or knocking sound is heard inside, it means that the core or contacts have broken, and the part requires replacement. Also inspect the insides for burning or melted plastic.
Checking the relay contacts with a multimeter in dial mode should show a short circuit on certain pairs of contacts depending on the position. If the circuit does not ring or, conversely, rings everywhere, the relay is faulty. Replacing this part is the most frequent and inexpensive repair.
☑️ Checking the start relay
Do not forget that in some models of refrigerators, especially old ones, a thermal protection relay is used. It can be triggered when the windings overheat. If it is faulty, it will open the circuit even when the engine is cold, preventing it from starting start.
Checking the compressor windings with a multimeter
If everything is in order with the relay and voltage, you need to check the integrity of the windings of the electric motor itself. To do this, remove the start relay and gain access to three contacts on the compressor housing. Usually they are arranged in a triangle.
Using a multimeter in resistance measurement mode (Ohm), we ring the pairs of contacts one by one. You need to find the starting, working winding and common wire. The resistance of the starting winding is always higher than the working winding, and between the common and working contacts it is minimal.
Below is a table with approximate resistance values for a working single-phase motor:
| Pair of contacts | Expected resistance | Diagnosis for deviation |
|---|---|---|
| Working - General | 10 - 30 Ohm | Open or short circuit winding |
| Starting - General | 30 - 90 Ohm | Open or short circuit of the winding |
| Working - Starting | Sum of the two above | Circuit malfunction |
| Case - Any contact | Infinity | Breakdown to the housing (dangerous) |
If the multimeter shows infinity (one on the left) on any of the windings, it means that breakhas occurred. If the resistance is close to zero, there is a short circuit. In both cases, the compressor must be replaced, since rewinding at home is impossible.
What is a breakdown to the housing?
A breakdown to the housing is a situation when an electric current passes through the motor winding to the metal casing of the compressor. This is deadly for humans, since touching the refrigerator body can result in an electric shock. The test is carried out with one probe on the contact, and the other on a stripped copper tube or body. The device should show infinite resistance.
Checking for interturn short circuit with current clamps
There are situations when the windings are intact, the relay is working properly, but the engine still does not start or the circuit breaker knocks out. This may indicate an interturn short circuit, which is difficult to detect with a conventional multimeter, since the resistance changes insignificantly.
For accurate diagnosis, current clamps are used. They are put on one of the power wires when trying to turn on the compressor. The starting current of a serviceable engine with a power of about 100-150 W should be from 1 to 2 Amperes, and a working one - about 0.5-0.7 Amperes.
If, upon startup, the clamps show a sharp jump to 10-20 Amperes and the protection is immediately activated, it means that there have been short circuit turns in the windings. The motor will jam or burn out completely if you continue to try to turn it on.
⚠️ Attention: Measure the current quickly, within 1-2 seconds. Holding the engine for a long time in the starting mode with a high current will lead to overheating and final failure of serviceable elements.
Mechanical blocking and jamming of the compressor
Sometimes the electrical part is fully operational, but the mechanical part does not allow the rotor to turn. This is called a "spell". This happens due to the production of rubbing steam, metal shavings getting into the cylinders, or oil solidifying during severe frosts (if the refrigerator was transported in winter).
There is a popular method of “wedging,” which sometimes helps to revive the unit. The essence of the method is to apply voltage directly to the starting and operating windings, bypassing the relay, in order to create maximum torque.
However, if after several attempts to “kick” the engine does not come to life, the valves or piston group are most likely damaged. In this case, the compressor will work, but will not create the necessary pressure in the system, or will simply hum uselessly.
Frequent questions and answers (FAQ)
Is it possible to replace the compressor yourself?
Theoretically it is possible, but this requires special equipment: a burner, a vacuum pump, a pressure gauge station and skills in soldering copper pipes. Refueling Freon of a certain brand and in a strict quantity is also required. Without experience, there is a high risk of completely ruining the refrigerator.
Why does the new compressor heat up more than the old one?
Modern engines often have a higher energy efficiency class and operate at higher housing temperatures. If the temperature does not exceed 90 degrees and the refrigerator freezes, this is normal. However, it is worth checking whether the starting one is selected correctly relay for the new model.
How much does it cost to diagnose a compressor in the service?
The cost of on-site diagnostics varies, but usually it includes checking the electrical circuit, measuring current and pressure. If you refuse repairs, you may be charged a separate fee for diagnostics. Exact prices depend on the region and policy service center.
Does the compressor hum if there is no freon in the system?
Yes, the engine will operate normally, since its task is to pump gas. The lack of refrigerant does not affect the rotation of the motor shaft, but the refrigerator will stop cooling, and the compressor itself may overheat due to the lack of cooling by freon vapor.