Failures in the operation of the cooling system often become an unpleasant surprise for owners of household appliances. If you notice that the food in the chamber has stopped freezing or, conversely, has turned into ice blocks, most likely the problem lies in the temperature sensor. In refrigerators of the brand Nord, which have proven themselves to be reliable and easy-to-maintain units, adjusting this unit often solves the problem without calling a technician.
The thermostat, or thermostat, is the “brain” of the cooling system, responsible for turning the compressor on and off. Incorrect setting can lead to increased energy consumption and reduction motor service life. Understanding the principles of its operation will allow you to independently eliminate many typical malfunctions.
In this article we will analyze in detail the design of thermostats used in various models Nordand provide a step-by-step algorithm for calibrating them. You will learn how to distinguish a sensor failure from a freon leak and when it is really necessary to replace a part.
The operating principle and design of a thermostat
A thermostat is a device that responds to changes in temperature inside the refrigerator or freezer. In classic models Nord, such as the DM or T series, mechanical sensors with a bellows are most often used. Bellows is a corrugated container filled with a temperature-sensitive gas or liquid, which contracts when cooled and expands when heated.
When the temperature in the chamber rises above the set value, the gas in the bellows expands, pressure is transferred to the membrane, which closes the electrical contacts. At this moment the compressor starts. As soon as the air cools to the desired level, the reverse process occurs and the circuit opens. Electronic thermostatsfound in newer models, use thermistors whose resistance changes depending on the heat, but the principle remains the same - control of the motor operating cycles.
It is important to understand what adjustment implies changing the tension force of the spring, which counteracts the pressure of the bellows. By turning the knob or calibration screw, you change the temperature range at which the contacts close. Setting accuracy directly affects the stability of the temperature regime.
What is the difference between a mechanical and electronic thermostat?
A mechanical thermostat is a simple electromechanical device that is not afraid of power surges. An electronic sensor (thermistor) transmits data to the control board, providing more accurate temperature maintenance, but requires stable power and is more difficult to diagnose without special equipment.
Diagnostics: when adjustment is needed
Before you start disassembling the unit, you need to make sure that the problem is in the thermostat. Users often confuse sensor failure with other malfunctions, such as capillary tube blockage or loss of compression. Symptoms may be similar, but treatment methods are radically different.
If the refrigerator Nord works non-stop, not turning off even with the minimum setting of the regulator, this is the first sign of a malfunction. It is also worth paying attention to the condition of the products: if they deteriorate in the refrigerator compartment, and the ice melts in the freezer, or vice versa - everything turns into ice, intervention is required.
However, there are signs that indicate that adjusting the thermostat will not help. For example, if the compressor does not start at all, but the light is on and the relay is clicking, the problem may be in the starting device. If the compressor is running, but there is no cold anywhere, and the tubes on the rear grille are cold, this is a sign of a refrigerant leak, and adjusting the sensor is pointless.
Preparation for setup and replacement
Any work related to the electrical components of the refrigerator requires compliance with safety precautions. Before starting the procedure, you must completely de-energize the unit by removing the plug from the socket. This is critically important, since the thermostat is energized at 220 volts.
To carry out the work, you will need a minimum set of tools. Phillips and flat-head screwdrivers, as well as pliers, are usually sufficient. If you plan to replace a part, it is better to purchase a new thermostat in advance that is compatible with your model Nord. The original part numbers are often indicated in the technical documentation.
Empty the refrigerator compartment of food and remove any shelves that interfere with access to the back wall or lampshade where the sensor is usually located. In some models, access to the thermostat is through the control panel on the top or side.
☑️ Preparation for repair
Step-by-step instructions for adjusting a mechanical thermostat
The setup process depends on the type of control. In mechanical models Nord adjustment is often carried out through a special hole in the thermostat housing or by turning the knob on the panel. If the knob turns, but the temperature does not change, the calibration screw pair inside may have come off.
For precise adjustments, you need to remove the regulator knob and find the locking screw or plastic rod. Carefully, with small turns (literally 1/8 or 1/4 turn), rotate the adjusting screw Remember the initial positionso that in case of failure you can return to it. After each change in the position of the screw, it is necessary to start the refrigerator and let it run a full cycle, which may take several hours.
If we are talking about internal adjustment of the spring tension (on some models of TAM or K-59 thermostats), then you need to remove the control unit itself. The thermostat body may have holes with sealing mastic. By carefully removing the mastic, you can gain access to the temperature range adjustment screws. One screw is responsible for the switching temperature, the other for the temperature difference (hysteresis).
Features of electronic thermostats
In modern refrigerators Nord with the No Frost system or electronic control, mechanical adjustment is impossible. Here all parameters are set via the control board. If the temperature does not correspond to the set one, most often it is necessary to replace the temperature sensor itself (thermistor), which has a certain resistance at a specific temperature.
The electronic sensor is checked using a multimeter in resistance measurement mode. The sensor is removed from the chamber, and its resistance is measured at room temperature, and then when placed in the cold (for example, in a refrigerator with a known temperature). Indications should change smoothly. If the resistance is infinite or zero, the sensor is faulty.
Sometimes a malfunction in the electronics can be resolved by rebooting the system. To do this, unplug the refrigerator for 15–20 minutes. If after switching on the error repeats and the sensor shows normal resistance, the problem may lie in the control board itself or the wiring.
Table of typical temperature conditions
When setting up, it is important to know target values. Below is a table that will help you figure out what temperature should be in different zones of the refrigerator Nord if the thermostat is working correctly.
| Storage area | Recommended temperature | Position regulator (conditionally) |
|---|---|---|
| Freezer compartment | -18°C and below | Maximum / 5-6 |