If your refrigerator suddenly stops freezing or starts making strange clicking sounds, do not rush to call a technician. Often the problem lies in a small but critical detail - relay. This component is responsible for starting and protecting the compressor, without which refrigerant circulation in the system is impossible. Understanding what a relay in a refrigerator means will help you save significant money on expensive repairs or replacement of equipment.
Inside this small device there is hidden complex mechanics, which is subjected to high loads every day. Starting relay gives a powerful impulse to start the engine, and thermal monitors monitors the temperature of the windings, preventing overheating. Failure of any of these elements leads to a complete stop of the unit. Let's figure out how this unit works, why it breaks and whether it is possible to repair it yourself.
The main functions and operating principle of the starting mechanism
The relay in refrigeration technology serves as an automatic switch. When the compressor is connected to the network, it requires a significant starting current, 3-5 times higher than the operating current. It is starting relay that provides this short-term voltage surge to the starting winding of the electric motor. As soon as the rotor reaches the required speed (usually in a split second), the device opens the starting winding circuit, and the motor continues to operate on the main winding.
In parallel with this process, thermal protection relaycomes into operation. It is a bimetallic plate that bends under the influence of temperature. If the compressor overheats due to prolonged operation or power surges, the plate opens the contacts, completely de-energizing the unit. This prevents the burning of an expensive motor-compressor. Overload protection is a key function that prolongs the life of the equipment.
Why does the relay click?
When Normal operation of the relay makes a quiet click when starting. If you hear frequent clicks every 10-15 seconds, this means that the compressor is trying to start, but the relay is opening the circuit due to lack of rotation of the rotor or overheating.
There are two main types of designs that can be found in modern and old models of refrigerators:
- 🔹 Electromagnetic relays: use an inductor to open the contacts when a certain current is reached; often found in older models.
- 🔹 Posistor (PTC) relays: modern devices where the role of a switch is performed by a ceramic element (posistor), which sharply increases the resistance when heated.
Typical symptoms of a relay malfunction startup
You can determine that the problem lies in the relay by characteristic signs that appear long before the refrigerator completely stops. An attentive owner will notice changes in the sound background and operating mode of the unit. Diagnostics begins with an analysis of the behavior of the equipment in the first minutes after switching on.
The most obvious sign is that the compressor hums, but does not start. You hear the strained hum of the motor, which lasts for several seconds, after which there is a loud click and silence falls. After some time (from 10 seconds to several minutes), the cycle repeats. This means that the starting relay is trying to start the engine, but does not cope with the task, and thermal protection emergency shuts off the power.
Other symptoms may be less obvious, but also indicate a malfunction:
- ❄️ Lack of cold: food in the chamber begins to deteriorate, although the indicators are on, but there is light.
- ⚡ Knocking out plugs: when the refrigerator is turned on, a short circuit occurs and the machine in the control panel is activated.
- 🔥 Housing heating: the rear grille or side walls of the compressor become excessive hot to the touch.
Visual inspection and initial diagnostics
Before proceeding with complex measurements with a multimeter, it is necessary to conduct a thorough external examination. The relay is located directly on the compressor housing, often covered with a plastic casing. To access it, you will need to remove the back panel of the refrigerator. Safety —the first rule: be sure to disconnect the device from the power supply!
After removing the casing, you will see a box placed on the compressor rod. Carefully remove it. If inside you find traces of burning, melted plastic, blackened contacts, or smell burnt insulation, the diagnosis is obvious. Mechanical damage case or contacts require immediate replacement of the part. Repair in this case is impractical.
Pay special attention to the posistor (if you have a modern model). It must be intact, without cracks or chips. If the ceramic element has become crumbled or blackened, it will no longer be able to perform its function as a switch. In electromagnetic relays, check the mobility of the core and the condition of the spring. They should not be rusted or jammed.
Checking the relay with a multimeter: step-by-step instructions
If a visual inspection does not reveal obvious defects, you need to “ring” the device with a multimeter. This will determine the integrity of electrical circuits. Switch the device to resistance measurement mode (Ohms). First, check the circuit between the contacts responsible for the starting winding. The resistance should be minimal (close to zero), which indicates a closed circuit.
Then check the thermal protection. In a cold state, the resistance between the input and output of the thermal relay should also be minimal. If the device shows one (infinity), then the circuit is broken and the relay is faulty. It is also important to check the posistor: its cold resistance is usually 3-15 Ohms. When heated (you can gently warm it up with a hairdryer), the resistance should increase sharply.
The table below will help you navigate the device readings during diagnostics:
| Test type | Normal reading | Malfunction sign | Action |
|---|---|---|---|
| Starting winding circuit | 0 - 5 Ohm | Infinity (1) | Relay replacement |
| Thermal protection (cold). Ohm | 0 - 1 Ohm | Infinity (1) | Relay replacement |
| PTC resistor (cold) | 3 - 15 Ohm | 0 Ohm or Infinity | Relay relay |
| Insulation resistance | Infinity | Any value | Replacing the relay (breakdown) |
Oxidation of the contacts can distort the readings, so before checking, clean them with fine sandpaper or a blade.
Do-it-yourself relay replacement algorithm
If the diagnostics confirmed a malfunction, the part must be replaced. Fortunately, the relay is a consumable item, and replacing it does not require special skills or soldering (in 95% of cases). The main thing is to choose an analogue with identical characteristics. The marking is usually applied to the body or indicated in the technical documentation for the refrigerator.
The replacement process is as follows: first remove the old relay, remembering or photographing the position of the wires. Then install the new device, pressing it tightly onto the contacts of the compressor. Make sure it sits straight and doesn't wobble. When installing, it is important to observe the orientation: often there is an arrow on the case indicating the “Up” direction, since some relays only work in a certain position.
☑️ Checklist before turning on
⚠️ Attention! Never attempt to operate a refrigerator with a faulty or removed relay by connecting the compressor directly. This is guaranteed to lead to burning of the motor windings and a fire hazard.
Nuances of selecting analogues and compatibility
When looking for a replacement, it is important to take into account not only the model of the refrigerator, but also the power of the compressor. The relay is designed for a certain range of currents. If you install a device with a lower rating, it will constantly overheat and shut down. If it is large, the starting circuit may not open in time, which is also dangerous.
Universal relays often come complete with a set of adapters for different types of compressors. This makes it easier to find a spare part if the original is no longer in production. However, for modern inverter systems universal solutions may not be suitable, since there the motor is controlled by an electronic unit, and not by a classic mechanical relay.
Pay attention to the number of contacts. There may be two, three or four. The connection diagram must completely match the original. If you are not confident in your abilities, it is better to contact a service center, where specialists will select and install a part with a guarantee.
Frequently asked questions and answers (FAQ)
How much does it cost to replace a relay at a service center?
The cost consists of the price of the spare part and the work of the technician. On average, replacement costs from 1,500 to 3,500 rubles, depending on the region and model of the refrigerator. Buying a relay yourself will cost much less.
Why does a new relay burn out after a short time?
This may indicate problems with the compressor itself (interturn short circuit, jammed pistons) or unstable voltage in the network. In such cases, a simple relay will not help, diagnostics of the motor is required and, possibly, installation of a voltage stabilizer.
Is it possible to temporarily start a refrigerator without a relay?
Theoretically, you can start the motor by applying voltage directly to the starting winding, but this is absolutely impossible to do without professional skills and equipment. This is dangerous to life and equipment. The lack of thermal protection will lead to rapid combustion of the compressor.
Where can I find the relay markings?
The marking is usually applied to the side or top edge of the plastic relay case. Also, the part number can be found in the refrigerator service book or on the manufacturer’s website for the unit model.