The question about the number of thermostats in the refrigerator often arises among equipment owners who are faced with unstable temperatures or want to carry out diagnostics themselves. The answer to this is not unambiguous and depends on the specific model, year of manufacture and, most importantly, the defrosting system. In old Soviet units and simple modern models, one sensor is most often found, while complex No Frost systems can contain from two to four or more control elements.
Understanding this how many thermostats are in the refrigeratoris critical for correct diagnosis of faults. If you incorrectly determine the number of sensors, you may look for a breakdown in the wrong place, or you may not find the control you need at all. Modern refrigerators are complex electronic devices, where each sensor performs its own function, be it monitoring the operation of the compressor or controlling the defrost system.
In this article we will analyze in detail how thermoregulation systems are designed in various types of equipment. We will look at the difference between mechanical and electronic sensors, their location and impact on the operation of the unit. This will help you better understand the operating principle of your household appliance and competently approach the issue of its maintenance or repair.
Dependence of the number of sensors on the type of refrigerator
The main factor determining the number of thermostats is the design of the refrigeration circuit. In classic single-chamber models or two-chamber refrigerators with one compressor and a static evaporator, it is most often installed one main thermostat. It is responsible for turning the compressor on and off depending on the temperature in the refrigeration chamber.
However, the situation changes dramatically if we are talking about two-compressor technology. In such models, where the refrigerator and freezer compartments have independent cooling circuits, there are always two thermostats. Each of them controls its own compressor, ensuring autonomous operation of the departments. This allows you to set different temperature conditions independently of each other.
⚠️ Attention: When trying to replace the thermostat in a two-compressor refrigerator, make sure that you are changing the sensor in the exact chamber where the problem is observed. Sensors can have different capillary tube lengths and temperature ranges.
Models with the system deserve special attention. No Frost. The number of temperature control elements in them increases. In addition to the main thermostat that controls the compressor, there are defrost sensors. They monitor the temperature of the evaporator in order to turn on the heating element in time and melt the ice, preventing overheating or underheating.
Mechanical thermostats: classics of the genre
Traditional mechanical thermostats are a sealed system filled with gas or liquid. The principle of their operation is based on the change in the volume of the working fluid when the temperature changes. When the temperature in the chamber rises above the set one, the pressure in the capillary tube increases, closing the contacts and starting the compressor. Most old models and budget modern refrigerators use exactly this circuit. The sensor is usually located inside the fridge compartment, and its sensitive part (capillary tube) is fixed to the evaporator or in a special channel. The number of such regulators in simple models is one. compressor.
Most older models and budget modern refrigerators use exactly this design. The sensor is usually located inside the fridge compartment, and its sensitive part (capillary tube) is fixed to the evaporator or in a special channel. The number of such regulators in simple models is equal to one.
There are also models with mechanical control, but an electronic control system. In them, a mechanical switch on the panel sets the mode, but direct control occurs through electronic module. This is an intermediate option, where the user turns the knob, but complex logic works inside.
Electronic temperature sensors in modern systems
Modern refrigerators are increasingly equipped with electronic temperature sensors, which are thermistors. Their resistance changes depending on the ambient temperature. Such elements are much more compact than their mechanical counterparts and allow the implementation of more complex control algorithms.
In electronically controlled systems, the number of sensors can vary from two to five or more. One sensor monitors the air temperature in the refrigerator compartment, the second in the freezer. Additional sensors can be installed to control the temperature in the zone freshness, at the inlet to the evaporator or to monitor the operation of the system No Frost.
The main advantage of electronic systems is high accuracy and the ability to display the real temperature on the display. However, diagnosing such sensors requires the use of a multimeter and knowledge of the nominal resistance values at different temperatures. Simply “clicking” them like mechanical ones will not work.
| Sensor type | Principle of operation | Accuracy | Difficulty of replacement |
|---|---|---|---|
| Mechanical | Change in gas/liquid volume | Medium (±2-3°C) | Low |
| Electronic (NTC) | Change in resistance | High (±0.5-1°C) | Medium/High |
| Defrost timer | Mechanical/Electronic counter | By cycle time | Average |
Specifics of refrigerators with the No Frost system
Refrigerators with the system No Frost require more complex control of temperature conditions. Here it is important not only to maintain cold, but also to remove moisture in a timely manner so that it does not turn into an ice coat on the evaporator. Therefore, in such units the number of thermoregulating elements is always greater than in drip models.
A typical circuit includes a main thermostat (or air temperature sensor), an evaporator defrost sensor and sometimes an overheating sensor. The defrost sensor is a key element that tells the control module or timer that the ice on the evaporator has melted and the heating element can be turned off.
If your refrigerator No Frost stops freezing, but the compressor is working, the problem often lies in the defrost sensors. There can be two of them: one for turning on the heating element, the other for turning off. A malfunction of any of them leads either to freezing of the evaporator or to constant operation of the heating element, which causes defrosting of the products.
Why are there more sensors in No Frost?
In the No Frost system, air circulates forcibly. It is important to control the temperature not only in the chamber, but also in the air supply channel, so as not to freeze the food near the fan.
Two-compressor models and independent circuits
In refrigerators equipped with two compressors, the operating logic is simple: one circuit is responsible for the fridge compartment, the second for the freezer compartment. Consequently, there are two thermostats here. They are completely independent of each other.
This means that the failure of one thermostat will not affect the operation of the second circuit. If your freezer has stopped cooling, but everything is fine in the refrigerator compartment, then the problem is localized in the freezer circuit. This greatly simplifies troubleshooting.
When replacing the thermostat in a two-compressor refrigerator, it is important to pay attention to the markings. Sensors for the freezer compartment often have a different temperature range (lower) than sensors for the refrigerator compartment. Installing an unsuitable element will lead to incorrect operation of the compressor.
☑️ Diagnostics of a two-compressor refrigerator
Fresh zones and additional sensors
Premium models of refrigerators are often equipped with special freshness zones (Zero Zone, Fresh Box, etc.). To maintain ideal conditions in these zones (usually around 0°C and high humidity), separate temperature sensors are used.
Thus, in a three-compartment refrigerator (refrigerator, freezer, fresh zone) with one compressor, two or three thermostats can be installed. One controls the main circuit, the other controls the damper that regulates the flow of cold air into the freshness zone.
The presence of additional sensors increases energy efficiency and food safety, but complicates repairs. Failure of the freshness zone sensor can lead to the fact that the products in this compartment begin to freeze or, conversely, quickly deteriorate, while in the main chambers the temperature will be normal.
⚠️ Attention: In models with electronic control and a freshness zone, sensor calibration can only be done through the service menu. After replacing the sensor, a reset or manual calibration may be required.
How to determine a faulty thermostat
Understanding what how many thermostats is in your refrigerator helps in diagnosis. The main signs of a malfunction: the refrigerator does not turn on at all, it works without stopping, or the temperature in the chambers does not correspond to the set temperature. In the case of mechanical thermostats, there is often no characteristic click when turning the knob.
To check a mechanical thermostat, you can dismantle it and place the sensitive part in a container with water of a certain temperature (for example, with melting ice to check for openness). If the contacts do not click, the element is faulty. Electronic sensors are checked with a multimeter in resistance measurement mode (Ohm).
If you find that one of the sensors in the system No Frost is lying according to the readings, this may block the start of the compressor or defrost. The control module receives incorrect data and goes into emergency mode. In such cases, replacing the sensor is the only solution.
Frequently asked questions (FAQ)
Is it possible to install a thermostat from another model refrigerator?
In most cases this is not recommended. Thermostats have different temperature response ranges and different lengths of the capillary tube. Installing an unsuitable element can lead to improper operation of the compressor and spoilage of food.
Why are there two thermostats in my refrigerator, but one compressor?
This is typical for models with a system No Frost or the presence of a freshness zone. The second “thermostat” can be an evaporator defrost sensor or a temperature control sensor in a separate zone, which controls the damper, and not the compressor directly.
How often should the thermostat be changed?
The service life of the thermostat is not strictly limited by time, it depends on the number of on-off cycles and operating conditions. They usually last 5-10 years or more. Replacement is required only when signs of malfunction appear.
Does the number of thermostats affect energy consumption?
Indirectly. More accurate electronic sensors and the presence of separate circuits allow optimizing the operation of the compressor, avoiding unnecessary load. A faulty sensor always leads to excessive energy consumption due to incorrect operation of the system.