The failure of the refrigerator to keep cold often becomes an unpleasant surprise, especially when food in the chamber begins to spoil. In most cases, the cause of the breakdown is the failure of the thermostat, which controls the cycles of turning the compressor on and off. Replacing this element is a task available to a home craftsman, but requires strict adherence to the sequence of actions and safety measures.
Before you begin disassembling the unit, you must completely de-energize the device. Unplug the power cord and make sure there is no perishable food left in the compartment that requires freezing. Carelessness at the preparation stage can lead to electric shock or damage to fragile parts of the cooling system.
The thermal relay, or thermostat, is an electromechanical sensor that responds to changes in temperature inside the refrigeration chamber. It is he who gives the signal to the compressor to start cooling or stop when the specified parameters are reached. Understanding the operating principle of this unit will help you avoid mistakes when installing and configuring it.
Diagnostics of a faulty thermostat
Before ordering a new part, you should make sure that the problem lies in the thermostat. Symptoms can vary: from a complete absence of cold to continuous operation of the engine without stopping. Users often confuse a sensor failure with a freon leak or a compressor malfunction, which leads to unnecessary costs.
Pay attention to the nature of the refrigerator’s operation. If the motor hums constantly and does not turn off even when ice has already formed inside, this is a sure sign of sticking contacts or loss of sensitivity capillary tube. In the opposite situation, when the unit is silent and does not respond to turning the adjustment knob, the control circuit is most likely broken.
⚠️ Attention: If you hear clicks when the refrigerator is running, but the compressor does not start, the problem may not be in the thermal relay, but in the start-protection relay or the motor itself. Conduct a full diagnostic before purchasing spare parts.
There is a simple way to perform an initial check without a multimeter. Connect the contacts of the wire coming from the thermostat directly. If after this the compressor starts working, then the problem is definitely in the temperature sensor. However, this method requires caution, since the refrigerator will work without stopping until you open the circuit.
Necessary tools and preparation
To successfully replace the thermostat, you will need a minimum set of tools that most men have in their homes. The main thing is to prepare a workplace with good lighting, since some fastening elements may be located in hard-to-reach places.
You will need the following tools:
- 🔧 Screwdrivers (cross and flat) for removing panels and terminals.
- 🔌 Multimeter or a tester to check the integrity chains.
- ✂️ Pliers for careful removal of terminal clamps.
- 🧤 Gloves to protect hands from sharp metal edges.
It is important to choose an exact copy of the old thermostat. Models may differ in the length of the capillary tube, type of contacts and method of fastening. If you buy a device with a tube that is too short, it may not be enough to fit in the chamber, and a tube that is too long will have to be carefully laid, avoiding creases.
Before starting work, it is recommended to take a photograph of the wire connection diagram. Insulation colors can fade over time, and relying solely on memory can be risky. The photo will become your main guide during assembly.
Removing the old thermostat
The process of removing a faulty part begins with access to its installation site. In most refrigerator models, the thermostat is located inside the refrigerator compartment, under a plastic cover, or outside, in the upper part of the case.
Sequence of steps for dismantling:
- Remove the temperature control knob by carefully pulling it towards you.
- Unscrew the screws securing the protective panel or lamp shade lighting.
- Remove the thermostat from the seat, being careful not to damage the capillary tube.
- Disconnect the electrical wires from the contact group.
Pay special attention to the capillary tube. It is very thin and easily pinched. If there is refrigerant left inside the tube, its release into the atmosphere is not dangerous, but it is better to avoid sudden movements. In some models, the tube is secured with special clips that need to be carefully released.
What to do if the capillary tube breaks?
If the tube breaks at the base, restoration is impossible - the entire thermostat must be replaced. Soldering at home is not recommended, as it will disrupt the seal and calibration of the sensor.
After removing the device, inspect the mounting hole. There should be no moisture, dirt or signs of corrosion. If necessary, wipe the installation area with a dry cloth. Clean contact is important for the correct operation of the new element.
Connection diagram and installation of a new relay
Installation of a new thermal relay is carried out in the reverse order of dismantling. The key is to connect the wires to the pins correctly. An error here can lead to a short circuit or improper operation of the compressor.
Usually three wires go to the thermostat:
- 🟡 Grounding (yellow-green) - attached to the housing or a separate contact.
- 🔴 Phase (red, brown or black) - goes from the network to the thermostat.
- 🔵 Compressor (white, blue or other color) - goes from the thermostat to the engine.
The table below shows typical contact markings, but always check with instructions for your specific model refrigerator:
| Contact on the thermostat | Wire color (typical) | Purpose | Where to connect |
|---|---|---|---|
| 3 or L | Red / Brown | Power input | From mains / cord |
| 4 or T | White / Orange | Output to compressor | To start relay |
| 6 | Yellow-green | Ground | To housing |
When connecting wires, make sure that the contacts fit tightly onto the terminals. Poor contact will lead to heating and eventual melting of the insulation. If the terminals are oxidized, clean them with fine sandpaper before installation.
☑️ Check before turning on
Setting and calibrating the temperature
After installing the new thermostat, it is necessary to configure it. Factory settings may not correspond to your operating conditions or the characteristics of a particular refrigerator model. Adjustment is carried out using a special screw located on the relay body.
To access the adjustment screw, it is often necessary to remove the plastic handle or protective seal. Turning the screw clockwise usually increases the shut-off temperature (the refrigerator will turn off at a higher temperature), and counterclockwise turns it down.
⚠️ Attention: Do not turn the adjustment screw more than one full turn at a time. A sudden change in settings can lead to incorrect operation of the compressor or freezing of products.
The optimal temperature in the main chamber should be from +2 to +6 degrees Celsius. To check, use an external thermometer by placing it in a glass of water in the center of the chamber. Measurements should be taken after several hours of operation of the unit.
Checking the performance of the system
The final stage is testing the repaired refrigerator. Plug in the device and set the regulator to the middle position. During the first 10-15 minutes, listen to the operation of the motor: it should start confidently, without buzzing or vibration.
Pay attention to the operating cycle. The refrigerator should reach temperature and turn off. The operating time before the first shutdown depends on the initial temperature inside the chamber and the load of products, but usually ranges from 30 to 60 minutes.