Searching temperature switch (thermostat) in the refrigerator is often the first step in diagnosing problems with cooling. If your equipment has stopped freezing or, conversely, turns food into ice blocks, most likely this particular sensor has failed. Understanding where it is located will save you time and money when calling a technician.
In most modern models, this component is hidden from the user’s eyes, as manufacturers strive for aesthetics and protection of internal components. However thermostat always has a fixed mounting point associated with either the evaporator chamber or the control panel. The exact location directly depends on the type of refrigerator: it is single-compressor or double-compressor, with a No Frost system or drip defrosting.
Before proceeding with disassembly, it is necessary to turn off the power to the unit. This is a basic safety rule and, if ignored, may result in electrical shock or electronic failure. Next, we will look at the main areas where this important control element is hidden.
⚠️ Attention: Electronically controlled refrigerators may use an air sensor or a sensor built directly into the chamber wall instead of a mechanical relay. In such cases, simply replacing the “twist” is impossible without flashing the module or complex calibration.
The location of the element is also dictated by the design of the evaporator. If you are the owner of an old model where you can see a frozen “snowball” on the back wall, you need to look there. In systems No Frost the search logic is completely different, since the sensors are often recessed into the air ducts.
Classic arrangement in single-chamber models
In old and simple single-chamber refrigerators, such as Soviet ones ZIL or early models Indesit, the thermostat is usually located inside the refrigerator compartment. It is easy to recognize by its characteristic temperature control handle, which often protrudes into the chamber or is located on the outer wall.
The mechanical part of the device, including capillary tube, is mounted on the evaporator. To get to the mounting location, you often have to remove the plastic cover or completely dismantle the back wall of the camera. The tube is carefully inserted into a special groove or pressed with a bracket to a metal surface.
It is important not to damage the thin tube during dismantling, since it is filled with freon and is sensitive to deformation. If the tube bursts, the refrigerant will escape and repair will not be economically feasible. Carefully bend the mounting brackets to release the sensor.
Sometimes manufacturers hide the relay housing behind a decorative panel above the door or at the top of the chamber. In such cases, look for screws hidden under the plugs. Access to them often requires the use of a Phillips screwdriver and a spatula to remove the plastic.
Specifics of two-chamber refrigerators
In two-chamber units, the situation is complicated by the presence of two independent circuits or a more complex cold distribution system. Here thermostat most often it is located in the refrigerator compartment, even if the freezer is located below. This is due to the fact that it is in the plus chamber that the average temperature is controlled.
The installation location is often masked by a lampshade or a separate plastic casing on the ceiling of the chamber. To remove the guard, you may need to carefully pry it open with a flathead screwdriver. Under the casing you will see the relay block itself and the wires suitable for it.
- 🔍 Look for a square or round plastic box near the ceiling of the chamber.
- ❄️ The capillary tube can go deep into the wall or be attached to an open area of the evaporator.
- 🔌 The wires are often gathered into a bundle and secured with clips so as not to interfere with air movement.
In models with a system Low Frost or partial No Frost the sensor can be built into the back panel. To replace it, you will need to remove the entire rear wall of the refrigerator compartment, which is a more labor-intensive procedure. Be prepared for the fact that you will have to unscrew many screws around the perimeter.
Pay special attention to the tightness of the passage of the capillary tube through the wall. If you break the seal, moisture will begin to seep into the insulation, causing corrosion and loss of thermal capacity. After replacement, be sure to check the integrity of the seal.
Where to look for the sensor in the No Frost system
Refrigerators with the system No Frost are designed fundamentally differently. They do not have an open evaporator in the chambers, so the thermostat (or defrost sensor) is hidden in the technical compartment. Most often we are talking about a defrost sensor, which controls the defrosting of the evaporator, hidden behind the rear panel of the freezer.
To access it, you need to completely defrost the unit, remove all the shelves and drawers in the freezer, and then remove the rear plastic panel. It is behind it that the evaporator and fan are located. Temperature sensor in such models it is often built directly into the evaporator housing or embedded in aluminum fins.
Unlike mechanical relays, electronic resistance sensors are used here. They are smaller in size and connect via connectors. An error in diagnostics here can be costly, since often it is not the sensor itself that fails, but the control module or defrost heating element.
⚠️ Attention: In No Frost systems, it is critically important to correctly install the sensor in the seat. Poor contact with the surface of the evaporator will lead to incorrect readings and ice freezing on the fan.
Sometimes in the freezer No Frost there is also a main thermostat that turns off the compressor. It can be attached to the air duct leading from the freezer to the refrigerator compartment. Check the top of the chamber, where cold air flows down.
Why do No Frost sensors fail?
Frequent heating and cooling cycles lead to microcracks in the sensor housing. Moisture penetrates inside, changing the resistance and distorting the readings for the controller.
Electronic control and hidden sensors
In modern models with a display on the door (Smart Cooling, Multi Flow), there may be no mechanical temperature relay at all. An electronic module is responsible for climate control, receiving data from several temperature sensorsthermal sensors
Such sensors usually look like small plastic “bullets” or tablets attached to the inner walls, often in recesses. They do not have an adjustment knob, and all settings are made through the interface on the external panel of the refrigerator.
| Sensor type | Installation location | Function |
|---|---|---|
| Main sensor | Middle part chambers | General temperature control |
| Defrost sensor | Evaporator (behind the wall) | Defrost control |
| Fan sensor | Air duct | Protection against warm air blowing |
| Fresh zone sensor | Bottom drawer | Maintain 0°C |
Diagnostics of such systems requires a multimeter and knowledge of the nominal resistances for a specific model. Simply “twisting the knob” will not work here. Often the problem lies not in the sensor itself, but in the oxidation of the connector contacts.
If your refrigerator is controlled electronically, replacing the sensor may require entering the service menu to reset errors. Without this, the unit may continue to operate in emergency mode or not start the compressor.
☑️ Diagnostics of the electronic sensor
Dismantling and checking the serviceability of the relay
After you get to the relay, you need to remove it. To do this, disconnect the wires (after remembering their position) and unscrew the housing mounting screws. A mechanical thermostat is usually held on by two screws or latches.
Checking is carried out with a multimeter in dial mode. At room temperature the contacts should be closed (or open, depending on the type). If you put the sensor in the freezer for 15 minutes, the state of the contacts should change. Lack of response indicates a malfunction.
When installing a new relay, make sure that the capillary tube fits into the same groove as the old one. The length of the tube matters: if it is too long, you can carefully roll it into a ring, but in no case bend it at an acute angle.
Sensing element It should fit snugly to the surface. Use thermal paste or a special clamp if the design requires it. Poor thermal contact will cause the refrigerator to turn on too late or too early.
⚠️ Warning: Do not attempt to repair the mechanical thermostat housing. This is a sealed system filled with gas. Opening will result in immediate loss of performance. Complete replacement only.
Typical mistakes when replacing a thermostat
The most common mistake is incorrect installation of the capillary tube. If it does not touch the evaporator or is pressed weakly, the sensor will “lie” about the temperature in the chamber. This will lead to cyclic switching on and off of the compressor or its continuous operation.
The second mistake is ignoring the markings. Thermostats have different temperature response ranges. Installing a relay from a different model may cause food to spoil or freeze. Always check the part number.
- ⚡ Forgot to unplug the refrigerator before starting work.
- 🔩 Damaged the wire insulation during reassembly.
- 🌡️ Used a thermostat with the wrong temperature range.
They also often forget to check the condition of the door seal after repair. If you kept the door open for a long time during replacement, the rubber could be deformed, which would negate all efforts to adjust the temperature.
After assembly and switching on, let the refrigerator operate for several hours without loading food. This will allow the system to reach operating mode and stabilize the temperature background. Only after this can the effectiveness of the repairs be assessed.
Is it possible to temporarily do without a temperature relay?
Theoretically, you can close the contacts so that the compressor works constantly, but this will lead to defrosting of the evaporator and failure of the compressor due to overheating. This is an emergency measure only to drain products.
Why does the new relay click, but the cold does not come?
The click means the mechanics are working, but if the compressor does not start or hums and turns off, the problem may be in the compressor start relay, and not in the thermostat. There may also be a lack of freon.
How to understand that the thermostat is stuck?
If the refrigerator works without interruptions and does not turn off even with the minimum handle setting, or vice versa, is silent at maximum cold, most likely the thermostat contacts are stuck in one position.