Sudden silence of the refrigerator or, conversely, its loud clicks followed by decay often indicate problems in the electrical circuit of the motor. If the compressor tries to start, makes a hum, but turns off after a few seconds, most likely the culprit is Start Protection Relay. This small component plays a critical role in providing starting voltage to the motor winding and protecting it from overcurrent.
Diagnostics of this part does not require sophisticated equipment, but does require compliance with safety precautions and care. Start relay (often called RTP or RT) is responsible for a short-term connection of the starting winding, after which it should open the circuit. If the mechanism sticks or the contacts burn out, the motor cannot reach operating mode, which leads to its overheating and thermal protection. In this article we will look at how to independently identify the malfunction.
Before proceeding with disassembly, it is necessary to completely de-energize the household appliance. Unplug the power cord and move the refrigerator away from the wall to gain access to the rear panel. Remember that any work on electrical components should be carried out only when there is no voltage in the network, otherwise the risk of electric shock or short circuit becomes too high.
Principle of operation and symptoms of malfunction
To understand exactly how to carry out diagnostics, you need to briefly understand the structure of the unit. Inside the plastic case there is a coil, a movable core and contacts. When power is applied, current passes through the coil, creating a magnetic field that draws in the core and closes the contacts of the starting winding. As soon as the motor rotor picks up speed, the current drops, the magnetic field weakens, and the contacts open. If this cycle is disrupted, the refrigerator stops cooling.
The breakdown can be determined by characteristic signs that appear long before the unit stops completely. Most often, owners notice that the engine hums for 5-10 seconds, then there is a loud click, and there is silence. After some time, the cycle repeats. This is a classic picture of thermal relay cutting off the power due to increased current, and the starting mechanism does not operate correctly.
There are several main symptoms that indicate the need for inspection:
- 🔊 Compressor hums, but does not start, followed by a click.
- 🌡️ The motor housing gets very hot, although the refrigerator does not cool.
- ⚡ The automatic switches in the electrical panel are knocked out when the equipment is turned on.
- ❄️ The temperature in the chamber is higher than the set temperature, the food starts deteriorate.
Sometimes the problem may lie not in the relay itself, but in the interturn short circuit of the motor windings. However, statistics show that it is the trigger mechanism that fails most often, especially in models older than 7-10 years. It is important not to ignore the first signs, since constant attempts to start can lead to combustion of the compressor itself, the replacement of which is not economically feasible.
⚠️ Attention: If after the click you smell a burning smell or see sparking, immediately stop trying to plug in the refrigerator. Operation in this condition can lead to a fire.
Dismantling and visual inspection of the part
To carry out diagnostics, it is necessary to remove the relay from the seat. It is usually mounted on the side of the compressor and covered with a plastic casing or metal bracket. Remove the back panel of the refrigerator by unscrewing the mounting screws and find the black cylindrical or cubic element that contains the wires.
Carefully remove the terminal block with contacts. In some models, for example Indesit or Atlant, you may need to slightly pry the latches with a flat-head screwdriver. After removing the block, the relay itself can be easily removed from the compressor rod. Be careful: old plastic cases can be fragile and crumble from careless movement.
Initial visual inspection often provides the answer to the question of a malfunction. Pay attention to the following points:
- 👀 Presence of melting on the case or blackening in the contact area.
- 👃 The smell of burning or burning plastic when opening the casing.
- 🔩 Condition of the rod: if it dangles freely inside the case, the mechanism broken.
- 💥 Cracks in the case through which moisture or dust could get in.
If no visual defects are detected, this does not mean the device is working properly. The contacts inside could have oxidized or burned so that it is not noticeable from the outside. In such cases, a more in-depth check using measuring instruments is required. Never try to disassemble the sealed relay case if it is not intended for this - it is easier and more reliable to replace the entire assembly.
Diagnostics with a multimeter: step-by-step instructions
The most accurate way to check is to use a multimeter in resistance (Ohm) measurement mode. This method allows you to assess the integrity of internal circuits and the condition of contacts. Before starting work, make sure that the device is in working order and the probes are not damaged. Set the switch to position 200 Ohm or dialing mode.
First of all, we check the thermal protection. Find the contacts going to the bimetallic strip. When cold, the resistance should be close to zero (usually less than 1 ohm), indicating a closed circuit. If the multimeter shows one or infinity, it means that the circuit is open and the protection is not passing current. This indicates that thermal relay has failed and requires replacement.
Next we move on to checking the starting mechanism. Here the sequence of actions depends on the type of device:
- Connect the probes to the coil contacts. The resistance should be small, but not zero.
- Check the contacts that close during startup. In a quiet state, they should be open (the resistance is infinite).
- Shake the relay. If you hear a knock inside, the core or contacts may have fallen apart.
- Turn over the relay (simulation of operation) and check whether the contacts close. In an inverted position, the chain should ring.
It is important to understand that different models have different designs. For example, in a relay type RT (RTP) the contacts are open in the quiet position, but in a relay type P-1 (RKS) the circuit may be different. If you are not sure of the readings of the device, compare them with the data of a working analogue or technical documentation.
☑️ Check with a multimeter
Table of typical values and faults
For ease of diagnosis, you can use a summary table that displays typical instrument readings and corresponding diagnoses. This data is relevant for most household refrigerators using standard single-phase compressors.
| Test type | Instrument readings | Diagnosis | Action |
|---|---|---|---|
| Thermal protection | Infinity (1) | Open circuit protection | Relay replacement |
| Start contacts | 0 Ohm in any position | Contacts sticking | Relay replacement |
| Inductor coil | Infinity | Coil winding burnt out | Replacement relay |
| Mechanics | Knocking when shaking | Destruction of the core | Replacing the relay |
It is worth noting that the coil resistance may vary depending on the compressor power and the relay manufacturer. However, the key factor is not the exact value in Ohms, but the presence or absence of conductivity where it should not be, and vice versa. If the device readings are unstable (the numbers jump), this is a sure sign of poor contact inside the device.
In some cases, the malfunction may not be caused by the relay itself, but by problems with the wiring or terminal block. Oxidized contacts on the connector can create additional resistance that prevents normal starting. Therefore, before installing a new relay, be sure to clean the contacts on the wires and check the tightness of the terminals.
⚠️ Attention: The technical characteristics of the relay may vary depending on the compressor model. Always check the markings of the new part with the original before purchasing and installing.
Replacement and installation of a new relay
If diagnostics confirm a malfunction, the only correct solution is to replace the part. Repairing internal relay components at home is practically impossible and does not guarantee longevity. The new part must have identical markings or be a complete analogue in terms of electrical parameters.
The installation process is simple, but requires care. Place the new relay onto the three contact pins of the compressor. It should fit tightly and with little effort. Make sure that the UP (top) marking is positioned correctly - usually on the top of the housing. Incorrect orientation may result in the mechanism not working due to gravity.
Next, connect the terminal block with wires. Make sure that the wires are not stretched and do not touch hot parts of the compressor. Clamp the fixing bracket, if provided by the design. After assembly, visually check all connections again for any gaps or protruding wires.
After installing the new component, you can conduct a test run. Plug in the refrigerator and listen. The motor should start with a characteristic hum, after 1-2 seconds a quiet click will be heard (the starting winding is turned off), and the unit will return to normal operation. If the hum continues and there is no click, immediately turn off the device - the problem may be deeper.
What to do if the new relay did not help?
If after replacing the relay the compressor still hums and does not start, the compressor itself may have jammed or an inter-turn short circuit of the windings has occurred. In this case, professional diagnostics are required by measuring current consumption and winding resistance directly.
Frequently asked questions and answers (FAQ)
Is it possible to start a refrigerator without a relay?
Technically, you can start a compressor without a starting relay using a button or an external starting device, but you can do this It is strictly not recommended for continuous use. Without protection, the engine will quickly overheat and burn out, since the starting winding will remain switched on.
Why does a new relay burn out after a short time?
A common reason is unstable voltage in the network or problems with the compressor itself (stiff running, bearing wear). If the motor consumes increased current, the thermal protection of the relay will be activated constantly, which leads to its degradation. It is also worth checking the capacitor if it is in the circuit.
What is the difference between the RTP and RKS relays?
The main difference is in the principle of operation and design of the contacts. RTP (thermal) uses a bimetallic plate and is more often found in older models, and RKS (starter) has a more complex contact system. They are not always interchangeable, so it is important to select an analogue strictly according to the catalog.
How much does it cost to replace a relay in the service?
The cost consists of the price of the part itself (usually from 500 to 1500 rubles) and the work of a master. Self-replacement allows you to save on the visit of a specialist, since the procedure takes no more than 15-20 minutes and does not require special skills, except the ability to use a screwdriver.