Modern refrigerators are considered reliable household appliances. They practically do not have complex electronics, therefore, at least parts that fail. The most common breakdown of the refrigerator is the failure of the thermostat. In the mechanical control scheme of the refrigerator, he participates in the operation of the engine-compressor. The temperature regulator is mounted in the chamber or on the front panel of the unit.
In the latest generation refrigerators, the thermostat replaced the thermistor. This device more accurately copes with its responsibilities. In this article we will try to figure out how to check the thermostat of the refrigerator.
The general scheme of the refrigeration unit
As you know, refrigerators and freezers work on freon. So far, this is the only gas that is not dangerous and, due to special properties, is capable of changing the state of aggregation. He is moving along the cooling system with the help of a motor-compressor. First, increased pressure is created on the rear wall of the unit, while a low pressure is formed on the evaporator. As a result, the freon located on the back of the cooler liquefies, and evaporation begins on the evaporator, which is confirmed by the refrigerator circuit attached to the instructions.
The device of the temperature control device
The thermostat is a fairly simple device. Even in modern cold rooms and refrigerators, this is a simple contact group. It is controlled by a gauge with a capillary tube, the end of which is in the chamber and measures the temperature. Today, there are two types of temperature controllers in refrigerators: mechanical and electronic.
A modern temperature controller has two main elements. This is a box in which there are control and actuating mechanisms, and a capillary extended into a tube. A box is a bellows (hermetically sealed tubular spring). The accuracy of the determined indicators depends on its tightness. The bellows compresses and stretches the spring, optimizing it with pressure indicators. Modern mechanical temperature controllers can have several springs. It depends on the destination: a refrigerator or a freezer.
More reliable and allowing you to smoothly adjust the operation of the entire refrigeration system - an electronic temperature controller for the refrigerator. The price of this device is much higher than mechanical and ranges from two thousand rubles (while a mechanical one costs up to a thousand). In an electronic thermal relay, a thyristor, sometimes a resistor, is responsible for the sensitivity.
In refrigerators with high energy consumption, such thermostats quickly fail. In “A +” class cooling units with linear compressors, electronic temperature controllers require replacement much less frequently. Therefore, most manufacturers of such equipment are switching to linear compressors with electronic temperature controllers today.
The principle of operation of the device
The direct purpose of the thermostat in the refrigeration unit is to maintain the temperature set by the consumer. In compression refrigeration devices, the temperature regulator turns the compressor motor on and off, and in absorption refrigerators, the heater. The device that controls the temperature in the cooling chambers is classified as gauge structures. This means that the operation of the unit depends on the instability of the pressure of its filler (usually gas) when the temperature fluctuates.
A mechanical temperature regulator is a lever device in which there is a power lever and a contact circuit. The elastic element (tubular bellows) of the temperature control system and the spring act on the power lever. The electrical part of the device is separated from the mechanical by an insulating gasket.
Working conditions for freon - concentrated steam, the pressure of which depends on temperature conditions. At the end of the tube, liquid gas already accumulates. A segment of the tube in which the separation of vaporous freon and liquid occurs, responds to temperature fluctuations. This segment is located in the cooling zone.
Thermostat location
The temperature controller is always connected to a knob that switches the temperature modes. In models of generations of past years, the thermal relay is located under a plastic cover inside the refrigerator. To replace it, you need to pick up the mode switch with a flat screwdriver, remove it, then dismantle the plastic cover.
In the models of recent years, from the attached instructions (scheme of the refrigerator), you can find out where the thermostat is located in the refrigerator. Most often, it is placed above the door. To get to it, you need to dismantle the mode switch and the plastic structure that covers the thermal relay.
Probable problems
There may be several breakdowns with the temperature controller. For example, the refrigerator freezes, but very weakly. In this case, you should try to adjust the temperature controller or replace it. Before checking the temperature regulator of the refrigerator, you need to make sure that the door closes tightly enough, and that the compressor operates at a given power.
It happens that the device began to leak or the compressor runs without stopping. It is not necessary that in each of these cases the temperature regulator fails. It is likely that the reason may be different, but the temperature regulator must be checked first.
Possible damage to the temperature controller
The most common cause of failure of the thermostat is physical wear. Why it happens? Faults in the temperature control of the refrigerator may be associated with loss of tightness, bloating, or oxidation. Cases of defective devices are known, but this is rare. Therefore, repairing such a system does not make sense. Replacing the thermostat in the refrigerator will cost less.
How to check the temperature controller yourself
There are several ways to check the temperature regulator of the refrigerator:
- The most reliable, experts say, is to conduct a test with a tester. He will show if there is resistance. To do this, the temperature controller is dismantled (after turning off the refrigerator from the network). You can find his location in the instructions that came with the refrigerator. But almost always it is under the temperature switch. If the tester is analog, you need to put it into the mode that measures resistance, and set the starting point. Then carry out a calibration (connect the probes and at the same time set the arrow to “zero”). The digital tester must be moved to the “200” or “chain ringing” position. Before making a measurement, you must first withstand the temperature controller in ice water. So the indicators will be accurate.
- How to check the thermostat of the refrigerator using an easier way? It is necessary to turn off the unit. It is necessary to remove the terminals from the thermostat and directly short-circuit the wires with a small length of wire. Next, turn on the refrigerator and listen to whether the compressor has started. Then everything is simple: if the compressor is silent, then you need to continue troubleshooting. Perhaps these are problems with the starting mechanism or the compressor itself. If the latter worked, it means that you need to replace the thermostat in the refrigerator.
The malfunction of the temperature controller in the refrigerator "Stinol"
This brand of refrigerators is very popular in our country. Almost the only drawback of such units is that the temperature regulator becomes very faulty (after 5-6 years of operation). The cause of the failure is the small working life of this device, supplied by the German company RANCO (5 years). The temperature control of the bellows, which is sensitive to temperature fluctuations, is broken in the thermostat.
Defects indicating that the refrigerator temperature regulator is faulty:
- “Stinol” does not start when you turn the switch to the “off” label (no click).
- The temperature in the refrigerator is higher than normal even with the position of the regulator "maximum".
- The compressor of the device works without stopping, even when the regulator knob is in the “off” position.
At home, it is impossible to accurately determine the malfunction of the temperature controller of the Stinol refrigerator. But if the compressor turns on when the contacts are closed by a jumper, it means that there is a high probability that the temperature controller is faulty, and therefore it is necessary to contact the company that makes urgent repairs of refrigerators.
Urgent troubleshooting
Damage to the refrigerator due to the failure of the thermostat, especially in the hot season, looks like the end of the world. Products disappear, there is no way to cool drinks, there may be a leak that will damage the flooring. Naturally, you must call the wizard.
It should be noted that urgent repair of refrigerators is always carried out at home. But a professional master with extensive experience will easily identify the malfunction by the named symptoms and come to the call with the necessary set of spare parts.
You can adjust the thermostat yourself
After replacing the temperature controller or during long-term operation, slight changes may occur in the operation of the refrigerator. There may be several reasons, but most often it is not a fully regulated temperature regulator. How to fix it?
Setting the thermostat of the refrigerator is a laborious and lengthy process. The time spent depends on the duration of the cycles between turning this device on and off. If time is limited, you can debug the thermostat by measuring the temperature in the freezer or refrigerator. In this case, there is no necessary correction for the ambient temperature.
Fundamentals of debugging a temperature controller
Adjustment consists in tensioning or loosening the power spring. To do this, find out where the power spring screw is located, in which direction the rotation will weaken the temperature, and in which it will increase for a particular refrigerator model. Typically, turning the screw on the spring clockwise increases the temperature, and counterclockwise decreases the temperature (one revolution is approximately 5-6 ° C).
Before starting work, you need to remove the gasket between the bellows and the chamber wall (after adjustment is complete, the gasket must return exactly in place). Then the temperature on the evaporator shelf is measured with the motor-compressor running and the average temperature regime. After 3-3.5 hours, the temperature is measured again. After comparing the initial and final temperatures, it is necessary to relax or tighten the power spring (after disconnecting the refrigerator from the mains).