A sudden cessation of cooling or, conversely, endless operation of the compressor often indicates a failure of the temperature sensor. In brand refrigerators Biryusa this unit is one of the most vulnerable elements of the electrical circuit that controls the climate in the chambers. Replacing a thermostat is a procedure that can be done independently if you have basic skills in working with tools and understand the principles of operation of household appliances.
Before you start disassembling, you need to make sure that the problem lies in the relay. If the compressor does not start at all, but when you close the contacts manually it starts to work, then the circuit inside the thermostat is broken. Also a sign of a malfunction is the absence of a characteristic click when changing the position of the adjustment knob. Thermoregulator responsible for opening and closing the compressor power supply circuit depending on the temperature of the evaporator.
In this article we will analyze in detail the diagnostic process, dismantling the old sensor and installing a new component. You will learn how to choose the right analogue if the original part is no longer in production, and how to avoid common mistakes during assembly. It is important to observe safety precautions, since the work will be carried out with an electrical appliance connected to the network, although we will do the replacement itself with the power turned off.
Diagnostics of a thermostat malfunction
The first step should always be a thorough check of the symptoms. If your refrigerator Biryusa stops turning off and works around the clock, while forming a “snow coat” on the back wall, this is a classic sign of sticking contacts in a closed state. In this case, the refrigerant circulates constantly, which leads to freezing of food and increased energy consumption. Thermostat in this situation, it simply does not receive a signal that the lower temperature limit has been reached or is physically unable to break the circuit.
Reverse the situation when the unit is silent and does not respond to turns of the regulator is also often caused by a break inside the sensor. The capillary tube, which is filled with a sensitive gas or liquid, may have become damaged or the contacts have oxidized to the point of impedance. To confirm the diagnosis, you can perform a simple test: remove the casing, disconnect the wires from the thermostat and connect them directly (being careful). If the compressor starts working, the problem is definitely in the relay.
⚠️ Attention: Carry out electrical tests only if you are sure of the integrity of the wire insulation. A short-circuit of live wires can cause sparking.
For accurate diagnostics, it is also useful to know the model of your device, since refrigerators Biryusa of different years of manufacture can be equipped with different types of sensors. Some models have electronic control, where instead of a mechanical relay a thermistor is used, which is tested with a multimeter. Mechanical devices are checked visually and by the method of exclusion.
Selecting a suitable thermostat model
Selecting a spare part is a critical stage, since not all thermostats are interchangeable. The main difference lies in the length capillary tube and temperature range of operation. If you install a relay with a shorter tube, it may simply not reach the measurement zone or, conversely, curl up into a ball, which will lead to incorrect temperature readings. The standard length for most models Biryusa is from 2.5 to 3 meters, but it is better to measure the old part.
It is also important to pay attention to the presence of a third contact on the body. In refrigerators with No Frost or drip defrost function, this contact controls the fan or defrost heater. If you install a two-pin thermostat instead of a three-pin one, the defrosting system will stop working, which will lead to ice fouling on the evaporator and eventual breakdown of the compressor. The marking on the case usually contains the manufacturer's code, for example TAM, K, RANCO or DANFOSS.
The following is a table of correspondence between popular models of thermostats used in Biryusa refrigerators:
| Original / Analog | Tube length | Number of contacts | Note |
|---|---|---|---|
| TAM-133 | 2.5 m | 3 | The most common option |
| K-59 L1102 | 2.5 m | 3 | Complete analogue of TAM-133 |
| TAM-125 | 1.3 m | 3 | For freezers |
| K-50 L1158 | 2.5 m | 2 | For single-chamber models |
When purchasing, pay attention to the quality of the adjustment knob rod. Cheap Chinese analogues may have play or crack at the first turn. Make sure that the thread for the fastening nut on the new thermostat matches the seat in your refrigerator, although in 90% of cases it is standard.
Necessary tools and preparation
For a successful replacement, you do not need complex professional tools, a standard home craftsman’s kit is enough. The main difficulty is access to the node, which is organized differently in different models. In older models, access can be through the lampshade, in new ones - through a plastic cover in the corner of the chamber. Prepare your work area and provide good lighting, since the insides of the refrigerator are often hidden in the shadows. Turk organized differently. In older models, access can be through the lampshade, in new ones - through a plastic cover in the corner of the chamber. Prepare your work area and provide good lighting, as the inside of the refrigerator is often hidden in the shadows.
List of necessary tools:
- 🛠️ Screwdrivers: cross and flat (different sizes for housing screws and terminals).
- 🔧 Pliers or round nose pliers: for carefully removing the tube and working with the terminals.
- 🔦 Flashlight: for inspecting the depth of the niche and the condition of the tube.
- 🧤 Gloves: preferably fabric with a rubberized palm, so as not to cut yourself on the sharp edges of the metal.
- 🧼 Dishwashing liquid: for cleaning the installation site from possible condensation or dirt.
Before starting work, be sure to defrost the refrigerator completely if there is ice in it. Water may get on the electrical contacts or inside the new thermostat, causing a short circuit. This will also make it easier to access the evaporator, next to which the sensitive tube passes.
☑️ Preparation for repair
Removing the old thermostat
The removal process begins by disconnecting the device from the power supply. Find the thermostat; in refrigerators Biryusa it is most often located inside the refrigerator compartment in a plastic box at the top right or left, next to the lamp shade. Remove the temperature control knob by pulling it towards you. There may be a screw underneath that secures the plastic cover, which needs to be unscrewed.
Carefully remove the plastic casing. Below it you will see a metal or plastic plate that presses the thermostat housing to the chamber wall. Unscrew the mounting screws. Now the most important thing is extraction capillary tube. It passes through a special hole in the wall of the refrigerator to the evaporator. It must be pulled very carefully, without jerking, so as not to damage the thin copper tube and not to break the tightness of the system.
⚠️ Attention: The capillary tube is filled with freon under pressure. If you damage it, the refrigerant will escape and repair will not be economically feasible. Proceed delicately.
After freeing the tube, disconnect the electrical wires. Before doing this, it is advisable to photograph the connection diagram or mark the wires with a marker so as not to confuse them when installing a new element. Usually the wires are simply removed from the terminals, but sometimes they can be secured with a clamp. Remember which wire is connected where, especially if you have a three-pin model.
What to do if the tube is stuck?
If the capillary tube is frozen to the evaporator, do not pull it by force under any circumstances. Turn on the defrost mode for a few more hours or carefully pour warm water from a syringe over the mounting area to melt the ice.
Installation of a new thermostat and configuration
Installation is carried out in the reverse order of dismantling. Insert the sensitive tube of the new thermostat into the hole until it stops, monitoring the process visually. The tube should fit tightly to the evaporator at the same point where the old one was attached. For fixation, a special bracket or clamp is often used, which provides thermal contact. Without a tight fit, the sensor will operate with a long delay.
Connect the wires to the terminals according to the diagram or photograph made earlier. Make sure the connections are secure and the wires are not loose. Reinstall the thermostat housing and secure it with screws. Replace the plastic trim and adjustment knob. At this stage, the mechanical part of the replacement is completed.
Setting the temperature is the final stage. After turning on the refrigerator, set the control knob to the middle position. Let the unit operate for several hours to allow the temperature to stabilize. If your refrigerator turns off too early and spoils food, or runs nonstop, an adjustment may be needed. On some models there is an adjusting screw under the handle, rotation of which (usually half a turn) changes the response temperature.
Typical errors and checking the result
One of the most common mistakes is incorrect orientation of the tube inside the chamber. If it touches the food or lies freely in the air and not on the evaporator wall, the thermostat will “lie.” They also often forget to tighten the housing mounting screw, which causes the sensor to dangle and not sense the real wall temperature.
The result is checked by cyclic operation of the compressor. In normal mode, the refrigerator Biryusa should turn on and off at intervals depending on the load and temperature in the room. Typically the cycle is 15-20 minutes of work and 15-20 minutes of rest. If the compressor hums continuously for more than 40 minutes, and the temperature in the chamber is already low, the sensor may not turn off the circuit.
- ❄️ Check for excess ice on the back wall after the first cycle.
- 🔊 Listen for a characteristic click when turning off compressor.
- 🌡️ Use an external thermometer to monitor the actual temperature inside the chamber.
If the situation has not changed after replacement, the problem may not lie in the thermostat, but in the compressor start relay or freon leak. In this case, it is better to stop independent repairs and contact specialists.
Is it possible to use a thermostat from another refrigerator?
Yes, if the mounting dimensions, capillary tube length and temperature range match. The main thing is that the contacts close and open at the same temperatures as the original. Universal models are often suitable, but require checking.
Why does the new thermostat click, but the compressor does not start?
This may indicate a malfunction of the compressor start relay or the motor itself. In this case, the thermostat is working (it clicks, which means the contacts are working), but the circuit breaks further along the circuit. Also check for voltage at the compressor inlet.
Do you need to evacuate the system when replacing the thermostat?
No, if you are only changing the electrical part and have not damaged the cooling system tubes. The thermostat is an external sensor, and its replacement does not require opening the freon circuit, so refilling or vacuuming is not necessary.
How long does a new thermostat last?
The average service life of a high-quality mechanical thermostat is 5-7 years during normal use. The resource depends on the number of on-off cycles and humidity conditions in the chamber.