Brand refrigerators Polyus, popular in past decades, are reliable, but time takes its toll, and the equipment begins to fail. The most common cause of compressor failure or incorrect operation is a failure of the start relay. It is this small unit that supplies the starting impulse to the motor winding, allowing it to start and enter operating mode.
If your unit stops cooling, hums, but does not start, or turns on for just a few seconds, the problem with a 90% probability lies in the starting system. Independent checking the relay allows you to save significant money on calling a technician and quickly bring the equipment back to life, since the procedure itself does not require complex equipment.
In this article we will analyze in detail the device of the trigger mechanism used in refrigerators Polyusand describe it step by step algorithm of actions to identify a defect. You will learn how to safely get to the node, what tools you will need and how to interpret the results of measurements with a multimeter.
Design features and principle of operation
In refrigerators Pole electromagnetic type starting relays were traditionally installed, although in later modifications they could also be found thermal protection of combined action. The main element here is an inductor mounted on a core and a moving contact. When voltage is applied, a high starting current passes through the stator winding of the compressor, which creates a magnetic field that draws in the core and short-circuits the starting winding of the motor.
As soon as the motor rotor reaches the required speed, the current drops, the magnetic field weakens, and the core is under the influence of gravity (or spring) returns to its original position, opening the starting winding circuit. In parallel with the starting one, it often operates thermal relay, which opens the circuit when the compressor overheats or when the rotor is jammed, protecting the engine from combustion.
The difference between the RTK relay and the RTP
The RTK Relay (Thermal Combination Relay) was installed on older models and had a vertical arrangement of contacts, while the RTP (Thermal Start Relay) is more compact and often has a horizontal installation with three contacts in a row.
It is important to understand that the malfunction may lie not only in the switch itself, but also in accompanying elements. For example, oxidation of the contacts or a break in the internal winding of the coil completely blocks the start. Visually, the relay housing may look intact, so internal diagnostics are mandatory.
Primary diagnostics without opening
Before proceeding with disassembly and testing with a multimeter, it is worth conducting an external inspection and audio diagnostics. Often the nature of the sound of a refrigerator working or trying to work can suggest the direction of the search. If you hear a click, followed by a hum, and then another click and silence, this is a classic symptom of trying to start.
Pay attention to the temperature of the compressor housing. If, after several attempts to start, it becomes hot, but no cold appears in the chamber, it means that the engine does not start, and the current flows only through the working winding or a jammed rotor. In this case starting relay either it does not open the circuit or does not close it at all.
It is also worth checking the integrity of the supply wires. Sometimes the problem is trivial: the terminals have oxidized or the wire has frayed at the point where it enters the relay housing. If there are no visual defects, we move on to a more in-depth analysis.
Rules for safe dismantling of the unit
Any work on the electrical components of the refrigerator should be carried out exclusively with the power disconnected from the mains. Unplug the cord from the outlet and make sure that there is no residual charge left on the capacitors or other elements, although this is rare in simple circuits. Allow the compressor to cool down if it has just been running. Pole this is rare. Allow the compressor to cool down if it has just been running.
The relay is usually located on the side of the compressor and is covered with a plastic or metal casing. To access it you need to:
- 🔌 Remove the rear protective panel of the refrigerator if it blocks access to the motor.
- 🔧 Carefully remove the fixing bracket or box holding the relay to the compressor terminals.
- ✋ Take a photo of the location of the wires before disconnecting it so that when assembly, do not mix up the contacts.
- 🧶 Disconnect the wires, having previously marked them with a marker according to the diagram.
Remove the relay from the compressor terminals with careful rocking movements. If it is tight, do not yank sharply to avoid damaging the fragile copper tubes or contacts. After removal, inspect the housing for melting, cracks or burnt marks.
Instrumental check with a multimeter
For For accurate diagnostics, you will need a multimeter (tester) switched to resistance measurement mode (Ohm). On old relays such as RTK or RTP, testing is carried out by checking the continuity of the coil and contacts. First, remove the relay cover to gain access to the internals.
Checking the inductor: connect the probes to the coil terminals. The resistance of a working coil is usually from 3 to 15 ohms, depending on the model. If the device shows one (infinity), it means that something has happened and the relay must be replaced. If zero, there is a short circuit of the turns. winding break, and the relay must be replaced. If zero, there is a short circuit of the turns.
Next, we check the moving contact. In a state of rest (the relay is turned over or lies on its side, as during operation), the contacts of the starting winding should be open. The resistance between them must be infinite. If the contacts are short-circuited in a quiet state, the mechanism is jammed and the engine will not be able to reach operating mode.
☑️ Test algorithm with a multimeter
Table of typical faults
For ease of data systematization, we have compiled a table that will help compare the device readings with the type of fault. This will allow you to quickly make a decision about repair or replacement of the part.
| Check parameter | Normal value | Fault symptom | Action |
|---|---|---|---|
| Coil resistance | 3–15 Ohm | Infinity (∞) | Replacing the relay |
| Contacts at rest | Open (∞) | Closed (0 Ohm) | Cleaning or replacement |
| Thermal protection | Closed (0 Ohm) | Open (∞) at cooling | Replacement of protection |
| Visual inspection | Clean contacts | Soot, soot, melting | Cleaning or replacement |
Special attention should be paid to the thermal relay if it is built into the case. When cold it should ring briefly. If the circuit is broken, it means that the protection has worked and has not returned to its original state, or the bimetallic element has burned out.
⚠️ Attention: If after replacing the relay the situation repeats (the new element burns out or the refrigerator does not start again), the problem may be in the compressor itself (turn-to-turn short circuit) or in low voltage in the network. Do not install new parts blindly without checking the voltage.
Replacement and final assembly
If the diagnostics showed a malfunction, the best solution would be to completely replace the unit with a similar one. For refrigerators Pole, relays of the RTK, RTP series or their modern analogues (for example, from Danfoss with a corresponding adapter) are often suitable. Select the part strictly according to the markings of the old one or the power of the compressor.
Installation of a new relay is carried out in the reverse order of removal. Make sure that the arrow on the relay body (if any) is facing up, as many models only work in a certain spatial position. Place the block tightly onto the compressor terminals until there is a characteristic click or stop.
After connecting the wires and installing the casing, you can perform a test run. Plug in the refrigerator. If after 3-5 seconds a click is heard and the compressor goes into quiet operation mode, the repair has been completed successfully. If the buzzing continues and a second shutdown click follows, the test must be repeated.
⚠️ Attention: Specifications and connection diagram may vary slightly depending on the year of manufacture of the specific Polus refrigerator model. Always check the technical documentation or the markings on the nameplate of your device before purchasing spare parts.
Frequently asked questions (FAQ)
Is it possible to repair an old relay rather than change it?
Theoretically, it is possible to clean the contacts from carbon deposits with fine powder sandpaper or a file if the problem is only oxidation. However, the resource of the restored element will be unpredictable, and there is a high risk of repeated failure in a short time. Replacing with a new one is a more reliable solution.
Why does the new relay buzz and click, but the refrigerator does not turn on?
This may indicate that the compressor itself is faulty (the piston group is jammed) or there are problems with the electrical circuit (a break in the motor winding). Also, the reason may be an incorrectly selected relay that does not correspond to the starting current of your motor.
Where can you find the relay markings on the Polus refrigerator?
The markings are usually applied to the side or top edge of the plastic relay case. Also, information about the type of starting device required can be found in the refrigerator passport or on the service sticker located inside the chamber or on the back wall.
Is it dangerous to operate a refrigerator with a faulty relay?
Yes, it is dangerous. If the relay does not open the start winding, the compressor will be overloaded, causing it to overheat, melt the insulation and possibly catch fire. In addition, this is guaranteed to put an expensive compressor out of action.