A sudden stop of the compressor or, conversely, its continuous hum often indicates a malfunction of the temperature control system. It is thermostat (or the thermostat) that is responsible for turning the motor on and off depending on the temperature in the chamber. If this element fails, the refrigerator ceases to maintain the set mode, which can lead to food spoilage or defrosting.
Before calling a technician or buying a new part, it is worth conducting independent diagnostics. Understanding how this unit works will save you time and money. In most cases, you can check thermostat at home, using a minimal set of tools.
Let's consider the main methods for identifying a malfunction, starting with visual inspection and ending with precise measurements of electrical parameters. It is important to act consistently and follow safety precautions when working with electrical appliances.
Main signs of a malfunctioning thermostat
The first step to understanding the problem is to analyze the behavior of the refrigerator. Symptoms may vary depending on the type of failure: the contacts could be “stuck” in a closed or open state. In the first case, the equipment will work without interruption, trying to cool the chamber to impossible values.
In the second case, the compressor simply will not start, and the temperature in the chamber will begin to rise. There may also be disruptions in the cyclicity of work when pauses become too short or excessively long. This is a direct signal that temperature sensor transmits incorrect data.
- 🔊 The compressor operates continuously without going into rest mode, even at minimum settings.
- ❄️ Ice forms in the refrigerator compartment, food freeze or, on the contrary, quickly deteriorate.
- 🔌 Complete lack of motor response when turning the control knob and turning it on.
- ⚡ Spontaneous switching on and off of the unit at chaotic intervals.
⚠️ Attention: If the refrigerator makes clicks, but does not start, The problem may be not only in the thermostat, but also in the start relay or the compressor itself. Do not rush to change parts at random.
Sometimes the cause of incorrect operation is mechanical damage to the capillary tube or loss of tightness of the bellows. In such cases, the refrigerant inside the tube evaporates and pressure on the contacts ceases to be created. Checking the integrity of the tube is an important diagnostic step.
Visual inspection and search for external defects
Before disassembling and using measuring instruments, it is necessary to conduct a thorough external inspection. Often the reason lies in obvious things that are easy to overlook. Inspect the regulator handle: it should sit tightly on the rod and rotate freely, without spinning idly.
If the thermostat is placed outside, check to see if there are any traces of melting, soot or sparking on it. For internal thermostats located inside the chamber, it is important to evaluate the condition of the capillary tube. It should not have kinks, creases or traces of corrosion.
Pay special attention to the place where the temperature-sensitive element is attached. In modern models Indesit or Atlant the tube can be secured with special clips. If the fastening is loose, the sensor does not read the real air temperature, but reacts to random changes, which confuses the operating algorithm.
Removing the thermostat for diagnostics
For an accurate check, the device must be removed from the housing. The dismantling process depends on the design of the refrigerator. In models with a top freezer, the thermostat is often located inside the refrigerator compartment, hidden by a plastic panel.
First unplug the appliance from the power supply. Then remove the regulator handle and unscrew the mounting screws holding the plastic trim. Carefully remove the thermostat housing, being careful not to damage the capillary tube that may be attached to the evaporator.
In some models, such as older Samsung or LG, access may be difficult. You will have to partially disassemble the inner lining. The main thing is not to apply excessive force to the tube, as damage to it will require refilling the refrigerator with freon.
☑️ Preparation for dismantling
After removing the device, disconnect the wires. There are usually three or four of them, and they are connected through a block. Remember or write down which wire is connected where. To check, we only need the contacts coming from the network and to the compressor.
Checking the thermostat with a multimeter (continuity test)
The most reliable diagnostic method is to use multimeter. Switch the device to resistance measurement mode (Ohm) or continuity mode. If you have an analog tester, make sure that it is working and the needle is at zero.
Connect the multimeter probes to the thermostat contacts. Under normal conditions at room temperature, the contacts should be closed and the device will display a resistance close to zero (or emit a beep). If the device shows infinity, it means the circuit is broken.
For a deeper check, you can place the thermostat sensitive element in a container with cold water (about 0°C) or, conversely, heat it with a hairdryer. When the temperature changes, the contacts should open or close, which will be reflected in the readings of the device.
| Contact state | Multimeter readings | Actions |
|---|---|---|
| Normal (heat) | 0 Ohm (Sound) | Thermostat is OK |
| Open circuit | 1 (Infinity) | Replacement part |
| Short circuit | 0 Ohm (constant) | Replacement of part |
| Unstable contact | Jumping values | Cleaning or replacement |
⚠️ Attention: Before taking any measurements, make sure that the refrigerator is completely unplugged from the outlet. Applying voltage to the multimeter probes in resistance mode will cause it to burn out.
If after “dialing” it turns out that the contacts do not respond to temperature changes or are constantly open, the part must be replaced. It is not economically feasible to repair modern sealed thermostats.
Is it possible to temporarily start a refrigerator without a thermostat?
Technically, you can short the wires directly to make the compressor work. However, this will lead to continuous operation of the motor and deep freezing of food. Use this method only for short-term testing of the compressor.
Alternative testing methods without a multimeter
What to do if you don’t have a tester at hand? There is a less accurate, but working method of checking using direct voltage. To do this, you will need a piece of wire with a plug or jumper. Be extremely careful: you are working with a mains voltage of 220V.
Connect the input wire (from the mains) to the output wire (going to the compressor), bypassing the thermostat contacts. If the compressor starts working after being plugged into the outlet, it means that the motor circuit is intact, and the problem is most likely in the regulator.
This method eliminates damage to the motor itself or the starting relay. However, it does not provide a 100% guarantee that the thermostat is working, since it does not test its ability to open the circuit when the desired temperature is reached.
Replacing and setting up a new thermostat
If diagnostics confirm a malfunction, you need to install a new one thermostat. When purchasing, pay attention to the marking: it must match the original or be a complete analogue in terms of the temperature range and the length of the capillary tube.
Install the new part in the reverse order: secure the tube, connect the wires according to the photos taken earlier, assemble the panel. After turning on the refrigerator, adjustment may be required.
Adjustment is made using a special screw located on the thermostat housing (often under the seal). Turning the screw clockwise usually increases the shutdown temperature, and counterclockwise usually decreases it. It is not recommended to turn the screw more than half a turn at a time.
⚠️ Attention: The characteristics of thermostats may vary depending on the refrigerator model and year of manufacture. Before installation, check the parameters of the new part with the manufacturer's technical documentation.
After replacement, let the refrigerator run for several hours in idle mode to ensure that the on and off cycles are correct. The temperature in the main chamber should stabilize within +2...+5°C.
Frequently asked questions (FAQ)
Is it possible to operate a refrigerator with a faulty thermostat?
Short-term - yes, if you manually control the temperature and turn off the device from sockets However, prolonged operation in this mode will lead to overload of the compressor, freezing of the evaporator and spoilage of food.
Why does the new thermostat click, but the refrigerator does not turn on?
The click indicates the contacts are working, but if the motor does not start, the problem may be in the start relay, the compressor itself, or the lack of voltage in the network. It is also possible that the new thermostat does not fit the parameters.
How often should the thermostat be changed?
The service life of the thermostat is usually 5-10 years. It does not require scheduled replacement if it performs its functions properly. Replacement is made only when signs of malfunction appear.
Does the length of the capillary tube affect the operation?
Yes, the length and diameter of the tube affect the response speed of the sensor. When replacing, it is important to use a part with similar geometric parameters, otherwise the temperature regime will be disrupted.