Restoring the functionality of refrigeration equipment often depends on correct diagnostics and installation thermostat. If your unit stops turning off or, on the contrary, does not want to start the compressor, the problem may lie precisely in the control circuit, where contact number 59 appears. This pin is often found on control boards or in relay wiring of domestic and imported models of previous years.
Incorrect connection of wires can lead to failure of the compressor or short circuit in the electrical network. In this material we will analyze in detail how to safely make a replacement, what tools you will need and what to pay special attention to when working with the electrical parts of household appliances.
Before you start disassembling, you need to make sure that you are dealing with a malfunction of the temperature sensor. Often the symptoms are similar to problems with the start relay or the compressor motor itself. However, if the continuity of the contacts shows a break or short circuit when the temperature changes, thermostat must be replaced.
Diagnostics of a thermostat malfunction
The first step should always be a visual and instrumental check. A thermostat is a mechanical or electronic device that opens a circuit when set parameters are reached. In older models that use contact markings with numbers (including 59), mechanical capillary thermostats are most often found. To check, you will need a multimeter. Switch the device to resistance measurement mode (Ohm) and ring the contacts. At room temperature the contacts should be closed (resistance close to zero). If you cool the sensitive element (capillary tube) to sub-zero temperature, the circuit should open. capillary thermostats.
To check you will need a multimeter. Switch the device to resistance measurement mode (Ohm) and ring the contacts. At room temperature the contacts should be closed (resistance close to zero). If you cool the sensing element (capillary tube) to sub-zero temperature, the circuit should open.
⚠️ Attention: Before any diagnostic work, be sure to disconnect the refrigerator from the power supply. Working with 220V voltage without the appropriate skills and tools is deadly.
If, when making a call, it turns out that the contacts are “stuck” in a closed state and do not open even with strong cooling, or vice versa - the circuit is constantly open, this is a direct sign of failure of the part. In such cases replacing the thermostat is the only correct solution to restore the operating cycle.
It is also important to check the condition of the insulation of the wires going to terminal 59. Often the problem lies not in the sensor itself, but in an oxidized contact or a frayed wire that shorts to the housing refrigerator.
Necessary tools and preparation
High-quality repairs are impossible without the right tools. To replace the thermostat and work with the contact group, you will need a minimum kit that any home craftsman can find. The main thing is to provide yourself with a comfortable workplace and good lighting.
The list of necessary equipment includes not only screwdrivers, but also specialized instruments for testing electrical circuits. Ignoring this step may result in damage to new parts or injury.
- 🔧 Set of screwdrivers (Phillips and flat head) for removing panels and terminal blocks.
- 🔌 Multimeter or tester for checking continuity and voltage.
- ✂️ Side cutters and a tool for stripping wire insulation (stripper).
- 🧤 Dielectric gloves to protect against accidental electric shock.
It is also recommended to prepare electrical tape or heat-shrinkable tubing. The contacts, especially in the evaporator area, are susceptible to moisture and condensation. High-quality insulation of connections will extend the service life of the new thermostat and prevent corrosion.
☑️ Preparation for repair
Connection diagram and contact markings
Having figured it out with the tools, let's move on to the electrical part. In most refrigerator circuits, the thermostat contacts have standard markings, but manufacturers can make their own adjustments. Contact "59" is often found in wiring running from the protection relay or starter to the control circuit.
A typical thermostat connection diagram includes three main terminals. The first is the phase input, the second is the output to the compressor, and the third can be responsible for the signal lamp or ground. In the context of your request, terminal 59 is most likely one of the power contacts or an output to the indicator.
| Contact number | Function | Wire color (standard) | Purpose |
|---|---|---|---|
| 3 | Input (L) | Brown/Red | Power supply |
| 4 | Output (Compressor) | Black/Blue | Start compressor |
| 6 | Lamp/Signal | Yellow/Green | Operation indication |
| 59 | Special. output/Grounding | Depends on the model | Add. control or housing |
It is important to understand that the color coding of wires does not always correspond to standards, especially if the refrigerator has been repaired previously. Therefore, you cannot rely only on the color of the insulation - you need to check with technical documentation or continuity of the circuit.
Why is accurate marking important?
Incorrect connection of contacts can lead to the fact that the refrigerator will work without stopping, ignoring the temperature settings, which threatens defrosting of food and overheating of the compressor.
If your thermostat has a contact marked 59, carefully examine where the wire goes from it. In some circuits, this may be the output on emergency sensor or the fan control circuit in No Frost systems.
Step-by-step instructions for replacing the thermostat
The replacement process requires accuracy and consistency of actions. First you need to gain access to the location where the thermostat is installed. In most models, it is located inside the refrigerator compartment, under a plastic cover, or in the engine compartment at the back.
Remove the old device by first photographing the position of the wires. This will help avoid confusion when connecting a new element. Disconnect the terminals, being careful not to jerk the wires sharply, so as not to damage them inside the insulation.
⚠️ Attention: The capillary tube of the new thermostat is very thin and fragile. When installing, avoid bending it at sharp angles and impacts, otherwise the refrigerant inside the tube will come out and the device will stop working.
Install the new thermostat in place of the old one. Secure it with standard fasteners. Connect the wires according to the photograph or diagram you took earlier. Pay special attention to pin 59 - make sure that it is connected to the appropriate terminal on the board or in the block.
After assembling all the components, you can begin testing. Plug in the refrigerator. If you did everything correctly, the compressor should start (or stop if the internal temperature is already low). Check the operation of the indication and the absence of sparking in the contact area.
Setting and calibrating the temperature
After replacing the thermostat, it may need to be adjusted. Factory settings are not always ideal for specific operating conditions. On the body of most mechanical thermostats there is an adjusting screw hidden under a seal or plug.
The rotation of this screw changes the pressure in the bellows, which shifts the temperature response threshold. Clockwise the temperature inside the chamber usually decreases (the unit works longer), counterclockwise it increases.
For accurate calibration, use an external thermometer placed in a glass of water in the center of the refrigerator compartment. Let the refrigerator set to normal (usually 5-6 hours) and compare the readings. If the difference is large, make (fine adjustments) with a screw.
- ❄️ Optimum temperature in the refrigerator compartment: +2...+4°C.
- 🥩 Temperature in the freezer: -18°C and below.
- ⏱ Interval between compressor starts: 10-15 minutes of operation, 20-30 minutes of rest.
You should not strive to set the minimum possible temperature. This leads to increased energy consumption and accelerated wear compressor. Electronic thermostats are calibrated through the control menu, if such a function is provided by the manufacturer.
Frequent installation errors
Even Experienced craftsmen sometimes make mistakes that can ruin all the work. One of the most common is poor contact in the terminal block. If the screw is loosely tightened, the connection will heat up, melt the plastic and eventually lead to a fire.
Another mistake is incorrect placement of the capillary tube. It should fit tightly to the surface of the evaporator along the entire length of the sensitive area. An air gap between the tube and the wall of the evaporator will lead to incorrect temperature readings and “floating” operating cycles.
They also often forget to check the condition of the insulation of the wires at the point where they exit the thermostat housing. Vibration during compressor operation can grind the insulation, which will cause a short circuit to the refrigerator body. This may be dangerous for the user.
⚠️ Attention: Never use aluminum wires to replace copper wires in the control circuit. Aluminum quickly oxidizes and loses contact, which will lead to unstable operation of the refrigerator.
Ignoring these nuances may lead to the new one thermostat burning out on the very first day of operation. Always check the quality of assembly before the final closing of the panels.
Questions and answers (FAQ)
Is it possible to temporarily close the thermostat contacts to make the refrigerator work?
Technically, you can close the contacts and the compressor will earn. However, the refrigerator will run continuously without turning off. This will lead to deep freezing of food, icing of the evaporator and, ultimately, to overheating and combustion of the compressor. Use this method only for a short-term check of the motor's performance.
What is the difference between the TAM-112 thermostat and the TAM-133?
The main difference is the response temperature range and the length of the capillary tube. TAM-112 is usually used for single-compartment refrigerators or double-compartment refrigerators, and TAM-133 is used for freezers. Installing an unsuitable model will lead to incorrect operation.
Why does the refrigerator click but does not turn on after replacing the thermostat?
The click indicates an attempt to start. If the compressor hums and clicks, but does not start, the problem may be in the start relay or the compressor itself (pistons are stuck). It is also possible that the new thermostat is faulty or incorrectly connected (there is no contact in the circuit).
How can I understand that pin 59 is really needed in my circuit?
If this contact was used in the original circuit, and you do not connect it, the indication, ventilation or overload protection may not work. Compare the number of contacts on the old and new device. If their number is different, look for a complete analogue or use a switching diagram for your refrigerator model.
Is it possible to repair an old thermostat rather than changing it?
Modern thermostats are non-separable devices. Attempts to repair them (flaring, cleaning contacts) are temporary and often lead to loss of bellows tightness. It is more reliable and safer to install a new certified analogue.