Refrigerators ZIL are deservedly considered one of the most reliable and durable units in the post-Soviet space. Their simple design and high-quality materials allow them to work for decades, but even such equipment can break down. One of the most common causes of compressor failure is the failure of the start-up relay, which is responsible for starting the engine and protecting it from overloads.
If you notice that your refrigerator has stopped freezing, and the motor hums for several seconds and clicks, or is completely silent, the problem with a high degree of probability lies precisely in this node. Start relay is a small but critical element of the electrical circuit. Checking it does not require complex equipment and is within the capabilities of a home craftsman who is ready to follow the instructions.
In this article we will look in detail at how to correctly diagnose a malfunction, what tools will be needed and what to pay special attention to when working with electrical equipment of Soviet and Russian refrigerators. Timely replacement this inexpensive part can extend the life of your refrigerator for many more years.
Signs of a faulty start-up relay
Before disassembling the equipment and arming yourself with a multimeter, you should make sure of the diagnosis visually and audibly. The refrigerator compressor ZIL usually operates cyclically, but if the relay breaks down, the nature of its operation changes. Symptoms may be different, but they, as a rule, clearly indicate a problem in the starting circuit.
The most common symptom is a characteristic click, after which the engine either does not start at all or runs for several seconds and stalls. If you put your hand on the compressor housing at this moment, you can feel that it is heating up, but there is no cooling. This indicates that starting winding receives power, but the engine cannot switch to operating mode.
Sometimes the situation looks different: the refrigerator hums, but the start does not occur, and after a while the thermal protection is triggered and a shutdown click is heard. In rare cases, the relay may “stick” when turned on, which leads to constant operation of the compressor without stopping, which is fraught with overheating and combustion of the windings.
- 🔊 The compressor hums for 3-5 seconds, then a click is heard and silence sets in.
- 🔥 The motor housing gets very hot, but the cold is in does not appear in the camera.
- ⚡ When turned on, circuit breakers are knocked out or plugs burn out.
- ❄️ The refrigerator works non-stop, without turning off for rest.
⚠️ Attention: If after clicking and trying to start you smell burning or burning plastic, immediately unplug the refrigerator. Continuing operation in this condition may lead to a wiring fire or complete failure of the compressor.
It is important not to confuse a relay malfunction with a breakdown of the compressor itself. If the engine hums but does not start, and the relay is working properly, the problem may be a jammed piston group. However, in 80% of cases with refrigerators ZIL the relay is to blame, since it is a consumable item with a limited resource of on-off cycles.
Design and types of relays in ZIL refrigerators
To correctly check the part, you need to understand how it's arranged. Refrigerators ZIL most often installed relays of the series RT (for example, RT-X, RT-X-1, RT-X-2, RT-X-3) or more modern analogues of the series P3. These devices are combined, that is, they combine starting and thermal protection.
Structurally, the device is a dielectric housing, inside which there are two main elements. The first one is electromagnetic coil with a movable core, which is responsible for connecting the starting winding at the moment of start. The second element is a bimetallic plate, which opens the circuit when the current or temperature increases critically.
What is the difference between RT and P3?
Relays of the RT series have a vertical connection and were often installed on compressors KhKD, KhKD-25. Relays of the P3 series (P3-1, P3-2) are more universal, can be installed both vertically and horizontally (marking “U” means universal) and are suitable for a wide range of compressors.
The operating principle is based on the physics of processes. When the refrigerator is turned on, the current passing through the motor windings is large. The electromagnet draws in the core, closing the contacts of the starting winding. The motor accelerates, the current drops, the core drops, opening the starting circuit. If the current does not drop (the motor is jammed), the bimetallic plate heats up and opens the common circuit, saving the motor.
| Relay type | Approximate compressor power | Installation features | Compatibility |
|---|---|---|---|
| RT-X / RT-X-1 | up to 140 W | Vertical | ZIL, Biryusa (old models) |
| RT-X-2 / RT-X-3 | 140-220 W | Vertical | ZIL, Oka, Saratov |
| P3-1 / P3-2 | up to 180 W | Universal | Most ZIL models |
| R-1 | up to 100 W | Horizontal | Low-power models |
When selecting an analogue for replacement, it is important to pay attention not only to the series, but also to the rated current. Installing a relay with a cut-off current that is too low will lead to constant false shutdowns, and if it is too high, it will cause the compressor to burn out. Rated current usually stamped on the product body or indicated in the technical documentation.
Removing the relay for testing
Checking the relay is impossible without removing it from the refrigerator. This process does not require special skills, but requires compliance with safety precautions. Before starting any work, be sure to disconnect the refrigerator from the electrical network! Working with live electrical appliances is deadly.
Get to the compressor, which is usually located at the lower rear of the unit. The relay is placed directly on the output contacts (plugs) of the compressor and is covered with a plastic or metal casing. In refrigerators ZIL fastening is often carried out due to a tight fit and fixing brackets or screws.
☑️ Preparation for dismantling
Carefully remove the protective cover. If it is metal and secured with screws, use a screwdriver. If it is plastic, it can simply move down or sideways. After removing the casing, you will see wires going to the relay. They need to be disconnected. In older models, the wires can be soldered, in new ones they can be connected through connectors.
The relay itself is removed by gently rocking it from side to side. Do not use excessive force to avoid damaging the ceramic insulator or compressor contacts. If the relay is “stuck” due to oxidation or heating, you can carefully help yourself with a flat screwdriver, prying up the housing at the base, but trying not to damage the plastic elements.
⚠️ Attention: Before disconnecting the wires, be sure to remember or photograph their connection diagram. By mixing up the contacts during assembly, you can cause a short circuit or burn the new device. In relays marked 1, 2, 3, 4, 5, the numbering of contacts is strictly regulated.
After dismantling, inspect the relay body. If the plastic shows traces of melting, soot, holes from sparking, or a persistent burning smell is felt, further inspection may not be necessary - the part definitely requires replacement. However, to be completely sure, it is better to carry out instrumental diagnostics.
Visual inspection and primary diagnosis
The first stage of testing is a careful visual inspection. Often external signs can tell more about an internal problem than measurements. Shake the relay near your ear: if you hear a clear knock or ringing of parts coming off inside, it means the mechanism is destroyed.
Inspect the contact groups. If you can carefully open the case (some models allow you to do this by prying the latches), check the condition of the contacts inside. They must be clean, without carbon deposits and oxides. Blackened contacts indicate a poor connection and constant sparking, which increases resistance and heating.
Pay attention to the bimetallic strip. It should be smooth, without signs of severe overheating (blue or purple tint of the metal). If the plate is deformed or has cracks, the thermal protection will not work, which is dangerous for the compressor.
- 👀 Presence of cracks or chips on the housing.
- 🔥 Traces of plastic melting around the contacts.
- ⚫ Black carbon deposits on the terminals connections.
- 🔩 Loose seat on the compressor shaft.
It is also important to check the condition of the wires suitable for the relay. The insulation must not be melted or brittle. If the wires are damaged, they must be repaired or replaced before installing a new relay, otherwise the problem may recur.
Checking the relay with a multimeter (continuity)
The most accurate diagnostic method is to check the electrical resistance with a multimeter. You will need to switch the device to resistance measurement mode (usually indicated as Ω or 200 Ohm). If your tester has a “dialing” mode with a sound signal, this is even more convenient.
First, let's check the thermal protection. Locate the contacts that go from the input wire to the compressor contacts (usually the common wire). When cold, the circuit should ring (resistance is close to zero, a squeak is heard). If the multimeter shows one (infinity), it means that the thermal protection is broken and the relay is faulty.
Then we check the starting coil. The resistance between the contacts responsible for the starting winding should be several ohms (usually from 3 to 30 ohms, depending on the model). If the resistance is zero, there is a short circuit; if it is infinity, the coil is broken.
There is a nuance in checking the electromagnetic mechanism. In some types of relays (with a vertical core stroke), the contacts of the starting winding are closed only when the relay is turned upside down (as when working on a compressor). In a horizontal position they can be opened. Therefore, when testing, try turning the relay over and see if the readings change.
If you do not have a multimeter, you can use a test lamp (a socket with a light bulb and two wires) connected to a 220V network. However, this method is less safe and less accurate, since it does not show the amount of resistance, but only the presence of contact. Safety when working with mains voltage should be a priority.
⚠️ Attention: Never try to test a relay connected to the compressor while it is energized. unless you have electrician skills. A short circuit in the test circuit can damage the compressor or multimeter.
Replacement and installation of a new relay
If the diagnostics showed a malfunction, the relay must be replaced. It is best to purchase a new part by taking the old one with you to the store so that the mounting dimensions and diameter of the hole for the compressor plugs match. For refrigerators ZIL universal relays of the series P3 or RT with the appropriate current are often suitable.
Installation is carried out in the reverse order of dismantling. Place the new relay onto the compressor contacts. It should fit tightly, without play. If the relay hole is larger than the diameter of the plugs, you can carefully tighten the contacts inside the relay with pliers (de-energizing the device!), but it is better to choose an exact analogue.
Connect the wires according to the diagram or photograph made earlier. Make sure the connections are secure. If the wires were soldered, use a soldering iron and solder, after stripping the wires. In modern models, it is enough to insert the connectors until they click.
After installing all the components, return the protective casing to its place and secure it. Make sure that the relay does not touch the metal walls of the housing or the condenser tubes to avoid vibration and unnecessary noise. Secure the compressor group if you removed the mounting bolts.
Frequent questions and problems after replacement
After replacing the relay, the owner may encounter a situation where the refrigerator seems to be working, but behaves strangely. For example, the compressor may be louder than usual or run longer. This may be due to the fact that a relay with an inappropriate cut-off current has been selected.
If the new device is selected correctly, but the refrigerator still does not start, the problem may lie deeper. Perhaps the compressor itself is faulty (interturn short circuit or jamming), or there are problems with the wiring, thermostat or starting capacitor (if it is in the circuit).
- 🛑 The compressor hums and immediately turns off - perhaps the motor is jammed or the relay is selected with too low a current.
- 🔊 Strong vibration noise has appeared - check whether the relay is touching the housing or tubes.
- 🌡️ The compressor works non-stop - check the thermostat and the tightness of the system.
- 💡 The light in the apartment flashes when starting - a problem in the wiring or too much starting voltage current.
In some cases, especially with very old models ZIL, it may be necessary to install an additional starting capacitor if there is no standard one in the circuit or it has dried out. This helps to facilitate engine starting, reducing the load on the relay.
⚠️ Attention: Technical characteristics of compressors and relays may vary slightly in different modifications of ZIL refrigerators. Always check the markings on the nameplate of your unit with the passport data of the part being replaced.
If after replacing the relay and checking all contacts the problem does not disappear, you should not continue the experiments. Further diagnostics require professional equipment (for example, to check the pressure in the system or the tightness of the circuit). In this case, it is wiser to contact a service center.
Is it possible to repair an old relay if it is burnt out?
Theoretically, you can replace the burnt coil or clean the contacts, but in practice this is a temporary measure. The factory calibration of the bimetallic plate is violated, and the relay will either not turn off the motor when overloaded (risk of fire), or will trigger falsely. Considering the low cost of new relays, repairing old ones is impractical.
What current should the relay have for the ZIL-640?
For most models of ZIL refrigerators (for example, ZIL-640, ZIL-630) with HKD type compressors, relays with a cut-off current of 1.3A - 1.6A are suitable (for example, RT-X-1, RT-X-2 or P3-1). The exact value depends on the specific modification of the compressor indicated on the tag.
Why does the relay heat up during operation?
Slight heating of the relay housing (up to 50-60 degrees) is normal, since the operating current of the compressor passes through it. However, if the housing becomes so hot that it is impossible to touch it, or the plastic melts, this is a sign of a malfunction (poor contact, incorrectly selected relay, or compressor overload).
How often do you need to change the relay in the refrigerator?
The resource of the starting relay is designed for thousands of switching cycles. Under normal conditions, it lasts 5-10 years or more. However, frequent power surges in the network, overheating of the compressor or poor ventilation of the rear wall can significantly reduce the service life of the part.