Owners of classic models of refrigerators of the 59 series are often faced with a situation when the equipment ceases to maintain the set temperature. The unit can work non-stop, becoming covered with an ice crust, or, conversely, turn on extremely rarely, allowing the food to defrost. In most cases, the root of the problem lies in a malfunction thermostat, which is responsible for the cyclic operation of the compressor. Replacing this element is a task that you can do yourself if you have basic skills in working with electrical circuits and follow safety precautions.
The replacement process requires care, since incorrect connection of contacts can lead to failure of the motor-compressor or even a short circuit. It is important to understand that a thermostat is not just a switch, but a complex device that responds to changes in the temperature of the evaporator. Before starting any work, you must completely de-energize the device by unplugging the plug from the socket, and prepare the necessary tools so as not to interrupt the process halfway.
In this article, we will analyze in detail the algorithm of actions that will help you successfully replace a failed sensor. We will look at the features of wire marking, methods for checking a new element and the nuances of setting that are specific to this series of equipment. A competent approach to repair will extend the life of your refrigerator and avoid an expensive service visit.
The principle of operation and diagnostics of thermostat malfunctions
A temperature regulator, or thermostat, is an electromechanical device that closes and opens an electrical circuit depending on the temperature of the sensing element. In Series 59 refrigerators, the sensor is usually mounted directly on the evaporator or in a special tube inside the chamber. When the temperature reaches the lower limit, the contacts open and the compressor switches off. As the temperature rises, the process is repeated in reverse order. If this cycle is disrupted, the food in the chamber deteriorates or an excessive layer of ice freezes.
The main sign of a breakdown is incorrect operation of the compressor. It may hum continuously, not turning off even at a clearly low temperature, or not start at all, remaining cold. It is also worth paying attention to the condition of the contacts. In older models of the 59 series, they could oxidize or burn, which leads to unstable operation. Diagnostics starts with a visual inspection and testing with a multimeter.
⚠️ Attention: Before taking any readings with a multimeter, make sure that the device is set to resistance measurement mode (Ohms), and the probes are working. Do not take measurements under voltage - this is dangerous to life and can damage the device.
To check, you need to remove the thermostat and immerse its sensitive tube in cold water with ice. If during cooling the resistance between the contacts changes (opens or closes depending on the type), then the sensor is working. If there is no reaction, the element must be replaced.
Necessary tools and preparation for work
High-quality preparation of the workplace and the availability of the right tools are the key to successful repairs. To replace the thermostat in a 59 series refrigerator, you will need a standard DIY kit. You should not use improvised means, as this can lead to damage to the plastic elements of the case or the insulation of the wires.
- 🔧 A set of screwdrivers (phillips and flat) for dismantling panels and fastening contacts.
- 🔌 Pliers or pliers for working with terminals and clips.
- 📏 Multimeter for checking circuit continuity and resistance.
- 🔪 A utility knife for carefully stripping the insulation if necessary.
- 📸 Smartphone for photographing the connection diagram before disassembling.
Particular attention should be paid to choosing a new thermostat. Models of the 59 series were often equipped with sensors marked TAM-112, TAM-133 or analogues from foreign manufacturers like Danfoss. It is important that the length of capillary tube the new sensor matches the original or is slightly longer (the excess can be carefully twisted). It is not recommended to buy a tube that is too long, as it is difficult to place in a limited space.
☑️ Preparing to replace the thermostat
Before starting work, the refrigerator must be completely defrosted and dried. Moisture inside the camera may cause a short circuit when first turned on. It is also recommended to cover the floor around the unit with a dry rag or towel to avoid damaging the floor covering and preventing slipping.
Removing the old thermostat
The process of removing the old sensor requires care so as not to damage the internal walls of the evaporator, especially if it is made of aluminum. In 59 series refrigerators, the thermostat is usually located at the top of the refrigerator compartment, often hidden by a plastic casing or control panel. First you need to remove the temperature regulator by pulling it towards you and unscrew the fastening screws under it.
After removing the decorative trim, access to the electrical part will open. It is important to act consistently here. First, the wires are disconnected from the contact group. In order not to confuse them during assembly, it is strongly recommended to take a photo or sketch a diagram. The color marking of the wires may differ depending on the year of manufacture and modification, so you cannot rely on color alone.
The next step is to remove the sensitive tube. It can be fixed in a special hole in the chamber wall or pressed with a bracket to the evaporator. Capillary tube very thin and fragile, so pulling it with force is prohibited. If the tube is inserted into the canal, it must be carefully loosened and pulled with forward movements. In some cases, you have to remove the back cover of the refrigerator from the outside to access the tube outlet.
What to do if the tube is stuck?
If the sensitive tube cannot be removed, try carefully warming the outlet with a hairdryer at a minimum temperature or use a lubricant like WD-40, but be extremely careful not to damage seals and insulation. Do not use force!
Connection diagram and wire marking
The most crucial moment is connecting a new thermostat. A mistake here could cost the life of the compressor. Contacts on thermostats are marked with letters or numbers. For domestic models of the 59 series, the most common designations are “3”, “4”, “6” or the letters “L”, “C”, “H”. Understanding the purpose of each contact is critical.
The contact designated as L (or "3") is usually the phase input from the mains. Contact C (or "4") goes to the compressor. The third contact, often designated as H (or "6"), is responsible for the light bulb or fan (if there is one). In two-contact models, the circuit is simpler: one input from the network, one output to the compressor. If your thermostat has three contacts, and the old one had two, the third may remain free or be used for indication, which requires studying the electrical circuit of a specific model.
| Marking | Purpose of contact | Where to connect |
|---|---|---|
| L (or 3) | Network input (Phase) | From the power cord / starting relay |
| C (or 4) | Output to the compressor | To the engine starting relay |
| H (or 6) | Lamp / Fan | To the refrigeration chamber lighting circuit |
When connecting wires, use the original terminals. If they are oxidized or broken, replace them with new ones, crimping them securely with pliers. Twists in the refrigerator's electrics are unacceptable, as they heat up and oxidize. After connecting, check that all connections are securely fixed by lightly tugging.
Installation and configuration of a new sensor
After the electrical connection, it is necessary to correctly install the sensitive tube of the new thermostat. It should fit tightly to the surface of the evaporator in the same place where the old one was located. For fixation, standard staples or special clamps are often used. If the new sensor comes with an insulating tube, put it on the free part of the capillary so that it does not respond to the air temperature inside the chamber, but only to the evaporator temperature.
Assemble the structure in reverse order: install the thermostat in its seat, secure the control panel, return the regulator knob. Make sure that the wires are not pinched by the housing and do not touch moving parts or hot elements (although there is little hot in the refrigerator compartment, friction with the metal will wear out the insulation over time).
The temperature is adjusted experimentally. After turning on, let the refrigerator run for several hours. If it turns off too early and the food is thawing, turn the knob to the colder side. If it freezes too much and the “fur coat” freezes, turn the knob towards lower values. The optimal temperature in the refrigerator compartment should be +4..+5°C.
Checking performance and typical errors
After assembly and first switching on, it is necessary to monitor the operation of the unit during the day. The compressor must turn on and off at regular intervals. Operating and idle time depends on the camera load, room temperature and the installed thermostat knob. Normally, the cycle is approximately 15-20 minutes of work and 20-30 minutes of rest.
A common mistake during repairs is ignoring the state of the start relay. If the thermostat is new and the compressor hums but doesn't start, or starts for a split second and clicks, the problem may be with the relay or the engine itself, not the temperature sensor. Also, beginners often forget to check the tightness of the system after manipulation, although when replacing the thermostat the circuit is usually not opened.
- ❌ Error: Incorrect connection of contacts (phase to the lamp instead of the compressor).
- ❌ Error: Poor contact of the sensitive tube with the evaporator (sensor "lies").
- ❌ Error: Using a thermostat with an inappropriate temperature range (for a freezer instead of a refrigerator).
If the refrigerator is operating normally, the repair can be considered complete. Regularly check the door seals and the cleanliness of the condenser at the back to reduce the load on the compressor and the new thermostat.
Can I use a thermostat from another refrigerator model?
You can use an analogue if the dimensions, length of the capillary tube and temperature response range are the same. However, it is better to select the original part number or its direct analogue, indicated in the manufacturers' correspondence tables.
Why does the new thermostat click, but the compressor does not turn on?
This may indicate a faulty start relay, motor protection, or an open circuit between the thermostat and the compressor. It is also possible for the contacts inside the newest but defective thermostat to stick.
Do you need to wait after installing a new thermostat before turning it on?
No special waiting is required if you did not use lubricant or water during installation. However, if defrosting was carried out, make sure that all the moisture has evaporated before connecting the unit to the network.