You noticed that your refrigerator stopped turning off or, conversely, stopped freezing food? Often the cause of such malfunctions is the failure of the thermostat. This small element is responsible for maintaining the set temperature inside the chambers, and its failure can lead to spoilage of supplies or waste of electricity. In this article, we will look in detail at how to diagnose the problem and replace the thermostat yourself.
Replacing a part yourself requires a minimum set of tools and basic electrical skills. However, it is important to understand that ignoring safety rules when working with electrical appliances is unacceptable. If you are not confident in your abilities, it is better to turn to professionals, but for most models the procedure is quite doable at home.
Before you start disassembling, you need to make sure that the problem lies in the thermostat. Sometimes the symptoms may be similar to a freon leak or a compressor malfunction. An accurate diagnosis before purchasing a new part will save you time and money, since working electrical products often cannot be returned.
Signs of a malfunctioning thermostat
Understanding the symptoms is the first step to successful repair. A thermostat is mechanical or electronic sensorthat opens or closes the compressor power circuit depending on the temperature in the chamber. When it breaks, the circuit either remains permanently closed or opens forever.
In the first case, the refrigerator works without interruption, trying to catch up with non-existent cold, which leads to freezing of the walls and food. In the second, the compressor is silent, and the temperature inside gradually becomes equal to room temperature. It is also possible that the equipment turns on and off too often, without having time to reach operating mode.
- ❄️ The compressor hums continuously, without going into rest mode, and a thick ice crust forms on the back wall.
- 🌡️ Inside the chamber it has become too warm, the food is spoiling, although the light is on and the compressor is not starts.
- 🔌 The device turns on for 1-2 minutes, then a long pause follows, and the cycle is repeated without achieving the desired cold.
It is worth noting that in some modern electronically controlled models, the role of a thermostat is played by thermal sensor (NTC), which looks different and is checked with a multimeter. Mechanical regulators, which will be discussed below, have a long capillary tube going deep into the chamber.
Preparation of tools and safety measures
Before starting work, you must turn off the power to the device. Unplug the cord from the socket - this critically important rulethat cannot be ignored. Even if you only change the plastic handle, the risk of touching live parts inside the case remains high.
You will need a minimum DIY kit. Usually a flathead and Phillips screwdriver, as well as pliers, are sufficient. To check the functionality of the old part, you may need a multimeter, but if you are changing the part based on symptoms, you can do without it by purchasing an analogue.
⚠️ Attention: Never try to remove the thermostat capillary tube by force or with sharp objects. The thin tube is easily pinched or bursts, which will make the new part unsuitable for installation.
Prepare the work area in advance. You will need a table on which you can lay out the parts in the order they are removed. This will help you avoid losing anything and reassemble the refrigerator in reverse order. A container for small screws will also be useful so that they do not roll under the refrigerator.
☑️ Preparation for repair
Removing the old thermostat
The process of removing the part may vary depending on the brand and model of your unit. In most cases, the thermostat is located inside the refrigerator compartment, often hidden behind a plastic panel or plastic temperature control knob.
First remove the control knob. It can simply be removed by hand or can be secured with a locking screw that needs to be unscrewed. After removing the decorative part, access to the fastening elements of the thermostat itself will open. Carefully unscrew the screws holding the sensor housing.
The most delicate stage is removal capillary tube. It passes through the door seal or chamber wall and is fixed inside to the evaporator. Don't pull too hard! Gently pull out the tube, making sure that it comes out smoothly, without kinks.
When the tube is released, disconnect the electrical wires. Before doing this, it is advisable to photograph the connection diagram or mark the wires with a marker, since mixed up contacts can lead to a short circuit. Usually there are only two or three of them, including grounding.
Compatibility and markings table
When purchasing a new part, it is important to pay attention not only to the appearance, but also to the markings. Manufacturers use different codes, but many thermostats are interchangeable. Below is a table of correspondence between popular models.
| Original (Tam, Danfoss) | Analogue (K50, K59) | Application | Tube length |
|---|---|---|---|
| TAM 133 | K59-L1275 | Single chamber refrigerators | 0.75 m |
| TAM 132 | K50-L1275 | Freezers | 0.75 m |
| TAM 145 | K59-P1275 | Two-chamber (No Frost) | 0.75 m |
| TAM 135 | K57-L1275 | Refrigerators with a weeping wall | 0.75 m |
Pay attention to the length of the capillary tube. If the new part has a longer tube than the old one, the excess can be carefully wound into a ring inside the body, but under no circumstances cut or shorten it. A shortened tube will disrupt the operation of the system.
Is it possible to use a thermostat with a longer tube?
Yes, you can. The excess length is carefully wound into a ring with a diameter of at least 5 cm and placed inside the refrigerator body, without touching the moving parts and hot parts. The main thing is to avoid creases and bends at an acute angle.
Installation of a new thermostat and assembly
Installation is carried out in the reverse order of dismantling. First, connect the electrical wires to the terminals of the new thermostat. Make sure connections are tight and secure. If there are oxides on the wires, clean them before connecting.
Then carefully insert the capillary tube into the hole. Work slowly, pushing it into the chamber until the sensing element is in place (usually it is mounted in a special socket on the evaporator). The fixation should be secure, but without excessive pressure.
Secure the thermostat housing with screws and install the decorative panel or handle. After assembling the entire structure, you can proceed to testing. Turn on the refrigerator and set the regulator to the middle position.
Checking functionality and setting
After switching on, listen to the operation of the compressor. It should start in a few seconds or minutes. Let the refrigerator run for at least 30-40 minutes until it reaches normal operating conditions. At this time, do not open the door frequently.
Check the temperature inside the chamber. If you have a thermometer, place it in a glass of water in the center of the refrigerator. After a few hours, the temperature should stabilize around +4...+5°C. If the cold is too strong or weak, tighten the adjusting screw.
Some thermostats have a small adjusting screw on the housing. Turning it clockwise usually increases the shutdown temperature (the refrigerator will turn off earlier), and turning it counterclockwise usually decreases it (it will freeze more). Be careful, make turns literally half a turn.
⚠️ Attention: If after replacing the thermostat the refrigerator still does not turn off or does not freeze, the problem may not be in the sensor. There may be a freon leak or a malfunction of the compressor start relay, which requires more complex repairs.
Common mistakes when replacing yourself
Beginners often make mistakes that ruin all their efforts. One of the most common is damage to the insulation of the wires or the tube itself during installation. This may result in an electric shock or a refrigerant leak if the evaporator is damaged.
Another mistake is buying a thermostat “by eye” without taking into account the type of refrigerator. Thermostats for freezers and refrigerators with system No Frost have different response temperature ranges. Installing an unsuitable part will lead to incorrect operation.
It is also important not to forget about grounding. If your refrigerator had a third wire (yellow-green) connected to the thermostat housing, it must be returned to its place. This ensures the electrical safety of the device.
- 🔧 Using a screwdriver that is too long, which can damage the plastic case or adjacent parts.
- 🚫 Ignoring the markings of the wires, which leads to incorrect connection of the contacts.
- 🌡️ Trying to adjust the temperature without first exiting the refrigerator to the mode (you need to wait several hours).
Is it possible to temporarily close the thermostat contacts?
Technically, you can close the contacts, and the compressor will work continuously. But this is absolutely impossible to do for constant use. The refrigerator will freeze until it stops, turning the food into an ice ball, and the compressor will burn out from overload very quickly. This is only permissible for a couple of minutes to check the motor.
Why does the new thermostat click, but the refrigerator does not turn on?
If you hear a click, it means the mechanics are working, but the circuit is not closed. The reasons may be poor terminal contact, burnout of the thermostat itself (defective) or a malfunction of the start relay/compressor. Check the voltage at the contacts with a multimeter.
Where can you find the markings on an old thermostat?
The markings are usually applied to the metal case or plastic cover. To see it, you often have to completely remove the part from the refrigerator. Look for codes like TAM, K59, Ranco, Danfoss.
How long does it take to replace a thermostat?
For an experienced technician, the process takes 15-20 minutes. For a beginner, taking into account the search for tools and careful disassembly, this can take from 40 minutes to 1 hour. The main thing is not to rush with the capillary tube.