How to check the temperature sensor of the washing machine

A temperature sensor is an internal element of a washing machine, which is responsible for heating water to a certain temperature and turning off the heating element. And if at one fine moment, the machine heats the water too much or does not do it at all, then the cause of the breakdown may be in the temperature sensor. How to test it for operability and replace if necessary, will be discussed further.

Varieties of sensors

One of three types of sensors can be installed in the automatic washing machine:

• gas filled;
• bimetallic or
• thermistor.

Each of them differs in the device, the principle of operation, which means it has its own characteristics when replacing and checking.

A gas-filled thermostat consists of two parts, the first is a metal tablet, the diameter of which is from 20 to 30 mm, and the height is up to 30 mm. This metal tablet is located inside the tank of the machine, so that it comes in contact with water to measure its temperature. The second part of the sensor has the shape of a tube made of copper, it is connected to an external temperature controller located on the control panel of the machine. Inside these parts of the sensor is pumped gas - freon. Under the influence of water temperature, freon expands or contracts, which leads to the closure and opening of the contacts going to the heating element.

The bimetallic temperature regulator also has the form of a tablet with a diameter of 20 to 30 mm and a height of 10 mm. Inside the tablet is a small bimetallic plate. When the water is heated to the selected temperature, the plate bends, which leads to the closure of the contacts, the heating of the water stops.

In the latest models of washing machines, a thermistor is installed as a temperature sensor. It is a metal cylinder with a diameter of about 10 mm and a length of 30 mm. Such a temperature sensor is fixed on the heating element itself. The principle of its operation is not based on the mechanical operation of the elements, but on the change in resistance when the water is heated to the desired temperature.

Checking the performance of the sensor and its replacement

In order to check whether the thermostat of the washing machine is working, you need to get to it. And for what the first thing we turn off the machine from the electrical network. Now you need to disassemble the car itself. The easiest way to “remove” the thermistor from the machine, because it is inside Ten. In most machine models, the heating element is located at the bottom of the washing machine.

To remove a thermistor, you must:

1. Open the back cover of the washing machine.
2. Disconnect the wires from the sensor to the external temperature controller.
3. Loosen the screw holding the Ten.
   
4. Get a thermistor from Ten.

Now when the sensor is removed, you need to take a multimeter and measure the resistance. We perform the following actions:

• configure the multimeter to measure resistance;
• hook the multimeter probes to the sensor contacts. At a temperature of 20⁰With a sensor resistance of about 6000 ohms.
• we lower the sensor in hot water and look at the change in the readings on the multimeter, when the temperature of the sensor changes. If the sensor is working, then the resistance will fall, and at a temperature of about 50⁰With it it will be equal 1350 Ohms.

If the thermostat is not working, then it must be replaced with a new one. It is not subject to repair. We collect the machine in the reverse order.

To get to the gas-filled sensor, in addition to opening the back wall of the washing machine, you will have to remove the front control panel. This is necessary in order to disconnect the external part of the sensor, as shown in the photo.

Returning to the back of the automatic machine, we find an output with wires on the tank body. Carefully in order not to damage the copper tube of the sensor we tighten the rubber insulation.Using a thin awl, gently poke the sealing gum around the copper tube and tighten it. Press lightly on the base of the sensor inward so that it pops out of the groove. After that, we pull out the temperature sensor through the hole in the tank. We disconnect the wire from the sensor and check it for operability.

The main malfunction in such sensors is a breakdown of the copper tube from which the freon. As a result, the performance of the sensor is disrupted. To replace it, we buy a temperature sensor complete with a switch and install it in place, performing all the collection actions in the reverse order.

As for the bimetallic sensor, to get it out of the washing machine, as in the previous case, you need to get to the tank. And then disconnect the thermostat from the wires. Now we connect the sensor contacts to the probes of the multimeter and look at the resistance readings. Next, we heat the sensor in hot water to a certain temperature and see how the resistance has changed, if it has fallen significantly, then the sensor is working, otherwise it will not.

The main reason for the breakdown of the bimetal sensor is wear on the plate. Replacing the sensor is quite easy, buy a new similar thermostat and install in place of the former.

Signs of sensor failure: major malfunctions

The normal operation of the washing machine depends on the health of the temperature sensor. External signs of failure of this part of the machine can be called the following:

• at any washing mode and at any selected temperature, the machine heats the water to boiling;
• during washing, the housing of the washing machine becomes very hot, and hot steam comes out of the drum door.

Such a breakdown requires immediate repair, otherwise it can lead to the burning of the heating element. BUT Tan's replacement will cost much more than replacing a temperature sensor.

Doing it yourself is quite possible. The most important thing is to remove the old temperature sensor and buy exactly the same in the store. Have a good repair!