The situation when the refrigerator stops turning off or, conversely, does not start the compressor at all, often confuses the owner. In most cases, the cause is a failure of the thermostat (thermostat). This small device is responsible for maintaining a set temperature inside the chambers, opening and closing the electrical circuit depending on the sensor readings.
Many people immediately call a specialist, believing that repairing refrigeration equipment is the lot of professionals with highly specialized tools. However, replacing a thermostat is one of the few operations that can be done independently if you have basic skills and accuracy. This allows you to significantly save your budget and restore the functionality of the equipment in the shortest possible time.
Before starting disassembly, it is important to understand the principle of operation of the unit. Thermoregulator receives a signal from a capillary tube filled with refrigerant, which responds to changes in thermal conditions. If the mechanism is stuck or the contacts are burnt, the cooling cycle is disrupted. In this article, we will analyze in detail the diagnostic process, dismantling the old element and installing a new one, paying attention to the intricacies of setting.
Diagnostics of a thermostat malfunction
The first step should always be accurate identification of the problem. Do not rush to buy spare parts until you are sure that the culprit is thermostatand not the starting relay or the compressor itself. Characteristic signs of a breakdown of the temperature controller are continuous operation of the motor without shutting down or a complete lack of response to turning the control knob.
There is a simple method of initial testing that does not require complete disassembly of the unit. If your refrigerator is a two-compartment refrigerator and everything in the freezer is frozen, but everything in the refrigerator compartment is warm, and the motor is constantly humming, this is almost guaranteed to be a problem with the sensor. In the opposite situation, when the equipment is silent, but the light is on, you need to rule out problems with the electrics.
- 🔍 Check if there is a click when turning the thermostat knob counterclockwise all the way.
- 🔍 Listen to the operation of the compressor: the cyclic switching must be observed.
- 🔍 Assess the temperature of the evaporator: if it is evenly covered with snow, but does not turn off, the sensor is “lying.”
For deeper diagnostics, you will need a multimeter. It is necessary to ring the thermostat contacts in cold and warm states. If the device shows an open circuit in both cases or, conversely, constantly rings regardless of the temperature, thermostat requires replacement.
Necessary tools and preparation
The success of the operation is 90% dependent on proper preparation of the workplace and the availability of the necessary tools. You don't need complex industrial equipment, but the set should be complete. The main requirement is safety, since the work is carried out with electrical appliances that have a metal body.
Prepare in advance a set of screwdrivers (phillips and flathead of different sizes), pliers with narrow jaws and side cutters. To work with wires, you may need an insulation stripper and electrical tape. If you plan not only to replace, but also to test a new element, a hairdryer or a container with warm water will be useful to heat the sensitive tube.
☑️ Preparation for repair
The critically important step is de-energizing device. Unplug the cord and gain access to the back wall or inside of the refrigerator compartment, depending on the design of your model. It is also recommended to defrost the unit a day before repair to avoid water flows during operation.
⚠️ Attention: Before starting any work inside the chamber, make sure that there are no glass jars or products left on the shelves that could fall if moved carelessly. Free up space in advance.
Access to the thermostat in different models
The location of the thermostat directly depends on the brand and year of manufacture of the refrigerator. In old Soviet-made models, such as ZIL or Saratov, as well as in modern ones Atlantakh, the regulator is often located inside the refrigerator compartment. Usually this is a plastic box on the wall into which the capillary tube goes.
In more modern units, for example, Indesit, Ariston or Stinol, the thermostat can be hidden behind the decorative panel of the chamber ceiling or built into the No Frost control system. In such cases, access is through the upper part of the internal volume, which requires careful removal of plastic plugs and screws.
There is also an option for location outside, on the rear wall of the housing, next to the compressor. This is typical for some models of built-in appliances or industrial refrigerators. In this case, you will have to remove the back metal cover to get to the electrical panel.
| Refrigerator model | Thermostat location | Access type | Features |
|---|---|---|---|
| Atlant, Minsk | Inside the chamber, on the left | Removing the lamp shade | Simple design |
| Indesit, Ariston | Behind the control panel | Removing the visor | Necessary remove the handle |
| Stinol (No Frost) | Inside, under the panel | Removing the plastic cover | Two sensors |
| Biryusa | Outside, rear | Removing the back cover | Access through the engine compartment |
Determine the exact modification of your device by checking the technical documentation. Incorrect determination of the installation location can lead to damage to the plastic interior elements when trying to dismantle the wrong panels.
The process of dismantling the old regulator
After access to the unit is obtained, it is necessary to fix the wiring diagram. This is the most important point: if the contacts are mixed up, the refrigerator may not start or, worse, the compressor may burn out. Take a photo of the connection or sketch out the color markings of the wires suitable for the terminals.
Carefully disconnect the block with the wires. If the contacts are oxidized, do not pull sharply - use pliers to loosen the connection. Then loosen the thermostat itself. Depending on the model, this may be a nut on a threaded sleeve or screws that secure the device body to the wall.
What to do if the wire comes off?
If during dismantling you accidentally damaged the wiring, do not panic. Strip the ends, twist them and solder them, then carefully insulate them with heat shrink. However, it is better to avoid such situations and act slowly.
The most delicate stage is extraction of the capillary tube. It passes through a hole in the wall of the refrigerator and is fixed inside the evaporator. It is strictly forbidden to pull it by force: thin copper easily bursts, and restoring the tightness of the system will require calling a technician with a vacuum pump. Carefully pull out the tube, helping yourself with pliers, but holding on to the insulated part.
⚠️ Attention: The capillary tube inside the evaporator is often secured with Velcro or staples. When pulling out the old thermostat, act smoothly, without jerking, so as not to damage the internal cooling circuit.
Installing and connecting a new thermostat
The new thermostat must be a complete analogue of the old one in terms of fit dimensions and the length of the capillary tube. If the tube is longer, you can carefully twist it into a ring, but in no case bend it or cut it. Shortening the tube will lead to a change in the volume of the working fluid and incorrect operation.
Insert the sensing element into the hole until it stops, controlling the force. Then secure the device body in its original place. Now let's move on to the electrical part. Using the photographs you took earlier, connect the wires to the appropriate terminals. For reliability, you can lightly pinch the contacts with pliers if they have become loose over time.
Pay special attention to grounding. If there is a separate screw for the “ground” on the thermostat housing (usually a yellow-green wire), its connection is required. This will ensure safe operation and correct operation of the electronics, if present in the circuit.
After assembling the electrical part, conduct a visual inspection. Make sure that no wires touch moving parts (if there is a fan) or hot surfaces. Reassemble the decorative panels and lampshades in the reverse order.
Configuration and performance testing
The final stage is testing the system. Plug in the refrigerator. The compressor should start immediately (if the chamber is warm). Allow the unit to operate until the first automatic shutdown. This may take from 30 minutes to several hours, depending on the load and ambient temperature.
If the refrigerator does not turn off for a long time, adjustment may be required. Many thermostats have an adjustment screw hidden under a seal or plastic plug. Turning clockwise usually increases the shutdown temperature (the refrigerator will turn off at a higher temperature), and counterclockwise turns it down.
- 🌡️ Normal operating cycle: 10-15 minutes of work, 20-30 minutes of rest.
- 🌡️ The temperature in the main chamber should stabilize at level +4..+6°C.
- 🌡️ In the freezer (-18°C), food should be stored without thawing.
During the initial startup, noisier operation or a prolonged hum may be observed. This is normal, as the system is returning to operating mode. However, if the motor runs continuously for more than 2-3 hours without a pause, it is necessary to repeat the diagnosis.
Is it possible to use a thermostat from another refrigerator model?
The use of analogues is possible, but only if the temperature range and the length of the capillary tube coincide. Different models are designed for different refrigerants and chamber volumes. Installing the wrong regulator will lead to incorrect temperature conditions.
Why does the new thermostat click, but the refrigerator does not turn on?
This indicates a problem not in the thermostat, but in the start relay or the compressor itself. It is also possible that there is an open circuit in the wiring between the regulator and the motor. It is necessary to test the circuit with a multimeter.
Is it necessary to evacuate the system when replacing the thermostat?
No, unless you damaged the capillary tube and did not release freon. The thermostat is located in the control circuit and not in the refrigeration circuit. Replacement is carried out without violating the tightness of the cooling system.