Modern two-chamber refrigerators operating in No Frostmode are complex thermodynamic systems where the circulation of refrigerant is strictly controlled electronically. One of the key elements of this system is the solenoid valve, which often causes unstable operation of the unit if it fails. Understanding exactly how this unit functions allows the owner of the equipment to independently diagnose the problem before calling a technician.
The main task of this component is to redirect the flow of freon between the evaporators of the freezer and refrigerator compartments. Depending on the temperature recorded by the sensors, the control module sends a signal to the solenoid, opening or closing the passage for the refrigerant. This ensures independent regulation of temperature conditions in different compartments, which is impossible in systems with a single evaporator without additional flow control.
In this article we will analyze in detail the design of the solenoid valve, consider typical scenarios for its failure and discuss methods for restoring the operation of the unit. You will learn why a refrigerator may stop freezing in one of the chambers, and how to distinguish a valve malfunction from a freon leak or compressor failure.
The purpose of the solenoid valve in the cooling system
In dual-circuit cooling systems solenoid valve performs the function of a switch. Without it, the refrigerant would circulate simultaneously through both evaporators, which would make it impossible to maintain different temperatures: the freezer should be about -18°C, and the refrigerator compartment should be +4°C. The solenoid physically closes one of the pipeline branches, directing the entire volume of freon to the desired circuit.
The principle of operation is based on the difference in the chambers' needs for cooling capacity. When the sensor in the freezer detects that the set temperature has been reached, the electronic module applies voltage to the valve coil. The magnetic field draws in the core, which opens the passage for freon into the second circuit (refrigerator compartment) or closes it, depending on the design of the system (normally closed or normally open).
It is important to note that there are systems with one compressor and one condenser, but two evaporators. It is in such models that the role solenoid is critically important. If your refrigerator has two compressors, then each circuit can use its own throttle or capillary tube, and control is carried out by turning the motor-compressors themselves on and off, although valves may also be present there for finer tuning.
- 🧊 Ensures independent operation of the temperature zones of the refrigerator.
- ⚙️ Controls the flow of refrigerant based on a signal from the electronic module.
- 🔄 Allows the use of one powerful compressor for two chambers.
Design features and device
Externally solenoid valve is a compact unit consisting of a housing, a solenoid coil and a movable core. The housing is usually made of brass or durable plastic that is resistant to refrigerants and oils. Inside the housing there are channels connecting the inlet pipe to the outlet pipes leading to different evaporators.
The central element is solenoid an electric coil, which, when voltage is applied, creates a magnetic field. This field acts on the ferromagnetic core (plunger), causing it to move. The movement of the core mechanically opens or closes the passage hole. The spring returns the core to its original position when the voltage is removed.
Modern models, such as LG or Samsung, often use valves with multiple outlets (two- or three-way). They may have complex internal channel geometries, which require precise orientation during installation. Incorrect installation can lead to freon going into the wrong circuit, or the system will operate with increased noise.
Is it possible to repair the valve without replacing it?
In 90% of cases, repairing the valve is impossible. If the coil winding is burned out or the plunger is jammed due to corrosion, the unit must only be replaced. Attempts to disassemble and clean it often lead to depressurization of the system.
Operating algorithm: from signal to cooling
The process of controlling the refrigerant flow is fully automated. The electronic module constantly polls temperature sensors (thermostats) located in each chamber. Based on the data obtained, a decision is made on the need to turn the solenoid on or off. The operation cycle is as follows: the refrigerator turns on, freon begins to circulate, cooling the priority chamber (usually the freezer).
As soon as the temperature in the freezer reaches the set value (for example, -18°C), the sensor sends a signal to the module. The module supplies voltage to solenoid valve. The plunger moves, redirecting the freon flow to the evaporator of the refrigeration chamber. The freezer at this point stops actively cooling and relies on maintaining cold thanks to thermal insulation.
When the temperature in the second chamber also reaches normal, the compressor turns off completely. When the temperature in any of the chambers increases, the cycle repeats. It is important to understand that the click that you can hear while the refrigerator is operating is precisely the switching sound solenoid. If there are no clicks and the temperature does not hold, there may be a problem in the control or the valve itself.
☑️ Diagnostics of valve operation
Typical malfunctions and their symptoms
The most common cause of failure solenoid valve is combustion of the coil winding. This can happen due to power surges or natural aging of the insulation. In this case, the valve stops responding to module commands and remains in one position (most often closed), which leads to defrosting of one of the chambers.
The second common problem is mechanical jamming of the plunger. A paraffin coating may form inside the system (especially if low-quality oil or freon with impurities was poured) or moisture may enter, causing corrosion. The plunger “freezes” and cannot move, even if the coil is working properly and a magnetic field is created.
Freon leakage through the valve seals is also common. Over time, the rubber gaskets lose their elasticity, and the refrigerant begins to leak out. This is accompanied by a decrease in the performance of the refrigerator as a whole. Visually, this can be seen by oily spots around the valve body or by a characteristic hissing, if you listen.
| Symptom | Probable cause | Test method |
|---|---|---|
| One chamber does not freeze | The plunger is jammed or the coil is burned out | Test with a multimeter, checking the voltage |
| The refrigerator runs non-stop | The valve does not switch flows | Comparison of temperatures in chambers |
| A hum is heard, but there is no cold | Partial blockage of the channel | Measurement of pressure in the system |
| Oil stains on the valve | Depressurization of the housing | Visual inspection and soap solution |
⚠️ Attention: If you find oily marks on the valve, under no circumstances continue to operate the refrigerator. This is a sign of a violation of the tightness of the circuit, which will lead to complete release of freon and combustion of the compressor due to lack of lubrication.
Diagnostics: how to check the serviceability of the unit
Primary diagnostics solenoid valve begins with a visual inspection and listening to the operation of the unit. If the refrigerator is humming, but one of the chambers is warm and the other is too cold (or vice versa), this is the first sign of a problem with switching flows. You need to make sure that the control module is sending a signal.
For a more accurate check, you will need a multimeter. The first step is to check the integrity of the coil winding. To do this, you need to remove the terminals from the valve contacts and measure the resistance. The normal value is usually from 1 to 3 kOhm (depending on the model, for example, for Indesit or Atlant values may differ). If the device shows an open circuit (infinity) or a short circuit (zero), the coil must be changed.
If the resistance is normal, you should check whether voltage is coming to the contacts at the moment when switching should occur. To do this, the refrigerator is connected to the network, and the multimeter probes (in AC voltage measurement mode) are connected to the wires coming from the module. At the moment of clicking, the arrow should deflect, indicating the presence of voltage (usually 220V). If there is voltage, but the valve does not click, it is mechanically faulty.
Replacing the solenoid valve with your own hands
Replacement solenoid valve is a procedure that requires special tools and skills in working with refrigeration equipment. Simply “unscrewing” the old one and “screwing on” the new one will not work, since the system is sealed and filled with freon. You will need a torch, solder, flux, a vacuum pump and a pressure gauge station.
The process begins by releasing the residual freon (if it has not yet escaped through the leak) and carefully unsoldering the tubes from the old valve. It is important not to overheat the new valve body itself when soldering, as the internal seals may melt. It is recommended to use a damp cloth to cool the case while soldering joints.
After installing a new unit, the system must be vacuumized for 15-20 minutes to remove moisture and air. Then the exact amount of refrigerant indicated on the refrigerator nameplate is charged. An error in the amount of freon will lead to incorrect operation of the entire system, regardless of the serviceability of the valve.
⚠️ Attention: Soldering and refilling with freon are classified as technically difficult. Improper soldering can lead to a fire, and moisture entering the system can lead to freezing of the capillary tube and costly repair of the compressor.
Frequently asked questions (FAQ)
Is it possible to temporarily block the valve in the open position?
Technically this is possible, but not recommended. If the valve is stuck in the “open” position for the freezer, the refrigerator compartment will stop cooling. If it is for a refrigerator, the freezer will defrost. This is a temporary measure that requires temperature control.
Why does the valve click but does not switch the flow?
Most likely, the coil is working and creates a magnetic field, but the plunger itself is jammed due to dirt or paraffin. It is also possible that the return spring inside the mechanism may be destroyed.
How much does it cost to replace an electromagnetic valve?
The cost consists of the price of the spare part itself (usually 1000-3000 rubles) and the cost of the technician's work (from 2000 rubles), including refilling with freon. The total amount depends on the model of the refrigerator.
Can the valve operate on 12 volts?
Domestic refrigerators use 220V valves. However, in car refrigerators or some industrial models, 12V or 24V solenoids may be found. Always check the markings on the coil before replacing.