A sudden increase in temperature in the refrigerator compartment or, conversely, the formation of an ice coat on the back wall often indicates a failure thermostat. This small unit is responsible for maintaining the set temperature by opening and closing the electrical circuit of the compressor. If you notice that your Biryusa refrigerator works without stopping or turns on too rarely, the first thing you need to do is check the serviceability of this component.
Self-diagnosis allows you to avoid calling a technician and save your budget, since the procedure testing is quite simple and does not require complex equipment. A basic set of tools and an understanding of how electrical circuits work is enough. In this article, we will analyze in detail the algorithm of actions, the necessary safety measures and methods for identifying malfunctions.
Symptoms of a thermostat malfunction
Before you start disassembling the unit, you need to make sure that the problem lies in the thermostat, and not in a freon leak or a compressor malfunction. The main sign of a breakdown is a violation of the cyclical operation of the motor. The compressor may hum continuously, trying to cool the chamber to impossible values, or be silent for days, allowing the food to defrost.
Pay attention to the condition of the food and the inner walls. If the refrigerator compartment is warm, but the ice in the freezer is melting, this is a clear signal. It is also worth listening to the clicks: if you turn the adjustment knob, but there is no characteristic sound of the contacts opening, thermostat jammed.
⚠️ Attention: If the compressor is hot to the touch, but does not start, or starts for a few seconds and stalls with a click, the problem may be in the starting relay or the motor itself, and not in the temperature sensor.
Sometimes the malfunction manifests itself in the form of condensation on the outer surface of the case or swelling of the doors, which indicates constant freezing of the moisture removal channel due to incorrect operation of the automation.
Preparation for diagnostics and safety measures
Any work related to the electrical components of the refrigerator requires strict adherence to electrical safety rules. The first and most important step is to completely disconnect the device from the power supply. Unplug the plug from the socket and make sure that there is no damage to the cord.
To carry out high-quality diagnostics, you will need multimeter (a tester) capable of measuring resistance (Ohm) and checking the integrity of the circuit (continuity). Also prepare a flat and Phillips screwdriver for removing panels, as well as a container with warm water to check the sensitivity of the sensor.
☑️ Preparing for testing
Free up space around the refrigerator to provide easy access to the back wall or inner chamber, depending on the model Biryusa. Remove all products if long-term defrosting or access through the door is required.
Access to the thermostat in different models
The location of the thermostat in refrigerators Biryusa depends on the year of manufacture and the specific series. In older models with mechanical control, the sensor is often located inside the refrigerator compartment, under a plastic cover or directly behind the control knob.
In more modern models, especially with the No Frost system or improved insulation, the thermostat can be moved outside, into a black plastic box on the back wall of the unit, next to the compressor. This makes access easier, but requires removal of the rear metal panel.
To remove the interior panel, carefully pry up the plastic latches with a screwdriver, being careful not to damage the fragile plastic, which becomes brittle in the cold. If access is through the handle, then it is usually removed with a slight tug towards you after unscrewing the hidden screw.
Features of dismantling in old models
In very old Biryusa refrigerators, the capillary tube of the thermostat can be glued to the evaporator. Tear it off very carefully so as not to damage the thin walls of the tube, otherwise the refrigerant inside the sensor will evaporate and the device will have to be replaced.
After gaining access, you will see a device with wires suitable for it. Remember or photograph the connection diagram so that during assembly you do not mix up the contacts, which can lead to a short circuit.
Visual inspection and initial check
Before using the devices, conduct a thorough visual inspection. Look for signs of oxidation on the contacts, blackening of the plastic, melted wire insulation, or moisture inside the thermostat housing. Any mechanical damage indicates the need for replacement.
Check the condition of the capillary tube, which goes deep into the chamber or evaporator. There should be no creases, cracks or swelling on it. If the tube is damaged, thermostat will not respond correctly to temperature changes.
Often the cause of the malfunction is not the sensor itself, but an oxidized contact in the block. Try carefully cleaning the contacts with alcohol or an eraser if plaque is visually visible, and check the operation again.
Checking the thermostat with a multimeter
The most reliable diagnostic method is checking the electrical resistance. Disconnect the wires from the thermostat terminals. Switch the multimeter to resistance measurement mode (Ohm) or continuity mode.
Touch the thermostat contacts with the probes. If the device is working properly and the ambient temperature is higher than the set one (for example, +20°C), the circuit should be closed and the device will show zero or a value close to it, and also emit a sound signal.
For a complete check, place the sensitive part of the thermostat (capillary tube with a cylinder) in a container with warm water (about 30-35°C). After a few minutes, the contacts should blur, and the resistance on the multimeter will rush to infinity (one on the screen). If this does not happen, the unit is faulty.
| State | Multimeter readings | Action |
|---|---|---|
| Normal (heat) | 0 Ohm (Sound) | Good |
| Normal (cold) | ∞ Ohm (No sound) | Good |
| Open circuit | ∞ Ohm in any case | Replacement |
| Short circuit | 0 Ohm in any case | Replacement |
Its check is usually not required for basic diagnostics, but it should not short to body.
Typical errors in diagnostics
Often amateur repairmen mistakenly blame the thermostat when the problem lies in a refrigerant leak. If there is no freon in the system, the temperature sensor will never receive a signal that the cold has reached and will keep the compressor on forever. In this case, replacing thermostat will not help.
Another mistake is ignoring the condition of the wires. A broken wire going to the thermostat will create the illusion that the sensor itself is broken. Always “check” the integrity of the wires to the terminals.
⚠️ Attention: Do not attempt to repair the internal mechanics of the thermostat. This is a sealed unit, and any violation of its integrity will lead to a final loss of functionality. Complete replacement only.
Also, you should not check the thermostat without waiting for the refrigerator to defrost. An ice crust on the sensor will distort the readings, and you can throw away a working part.
Replacement and adjustment of a new unit
If diagnostics confirm a malfunction, you must purchase a similar part. There is an article number stamped on the thermostat body (for example, TAM-133, K-59, etc.) by which you need to look for a replacement. For refrigerators Biryusa Universal models with a similar capillary tube length are often suitable.
Install the new thermostat in the reverse order. Pay special attention to the fastening of the capillary tube: it must fit tightly to the evaporator or be in a special channel in order to correctly read the temperature.
After installation, turn on the refrigerator and set the regulator to the middle position. Within 1-2 hours, check the operation: the compressor should periodically turn on and off, and the temperature in the chamber should drop to the set values.
Frequently asked questions (FAQ)
Is it possible to temporarily do without a thermostat?
Technically, you can close the contacts so that the compressor works constantly, but this will lead to deep freezing of food and possible failure of the compressor due to overheating. This solution is only for emergency transportation.
Which thermostat is best to buy to replace Biryusa?
Original spare parts are ideal, but often more expensive. Italian Danfoss (now Secop) and Polish Zanussihave proven themselves well. The main thing is that the parameters and length of the tube match.
Why doesn’t the new thermostat click?
If the temperature in the chamber has not yet reached the shutdown threshold, there will be no click. There are also possible options: a defective part, incorrect installation of the tube, or an adjustment screw that is not fully tightened.
Does it need to defrost the refrigerator before replacing?
Yes, complete defrosting (at least 24 hours) is required. This will allow you to remove excess moisture, check the system for the presence of ice in the channels and work safely with electricians.