The temperature sensor in the design of the washing machine is responsible for the correct heating of water according to the specified parameters and the heater is turned off when necessary. And if the washer has stopped heating the water or overheating it, then the culprit may be precisely the heat-sensitive element.
Checking and replacing the temperature sensor in the washing machine is the topic of our article. You will find useful tips, step-by-step instructions and recommendations.
What are the sensors
In the AGR, any of three possible types of sensors can be provided:
- gas filled;
- bimetallic;
- thermistor.
Each of these types has its own principle of operation and its own features of operability testing and replacement.
Gas filled sensor
Its design provides for two parts. The first is a metal “tablet” with a diameter of 2 to 3 cm and a height of up to 3 cm. The second part of the element is made in the form of a copper tube, which is connected to an external regulator on the CM control unit. The part is located in the inner part of the tank, in direct contact with water - this is how its temperature is measured. A gas known to everyone as freon (used in refrigerators) circulates inside such a sensor. When exposed to temperature, the gas contracts and expands, opening and closing the contacts connected to the heater.
Bimetal sensor
This part is the same shape as the previous one, with a difference only in height - up to 1 cm. There is a bimetallic plate inside the part. During heating of water, this plate bends, closing the contacts. As a result, the water stops warming when the set temperature is reached.
Thermistor
Such a temperature sensor is installed in all the latest models of cars. If your SM is no more than 7 years old, with a high probability it will have the same element. It looks like a cylinder of small dimensions with a diameter of up to 1 cm and a length of up to 3 cm. It differs from the previous ones by the type of fastening - it is installed on the heater itself. The sensor does not work according to the mechanical principle, but due to fluctuations in resistance during water heating.
How to check and replace the temperature sensor
Before checking the performance of the sensitive element, you need to slightly disassemble the machine body. Your task is to disassemble the case and get the thermostat out of the heater: this way you make it easier for yourself to check. In 4 machines out of 5, the heating elements and the thermistor are located under the tank, so it is not difficult to get to it. Before removing the sensor:
- Open the back of the washing machine by unscrewing 4 or 5 bolts around the perimeter of the lid.
- Remove the wiring connecting the element to the control board. Take a picture or mark the wires, so that later you can collect everything as it was.
- Loosen the heater mount - the retaining nut is centered exactly.
Now remove the thermostat. Having taken out the sensor, it must be checked with a multimeter and measure the resistance of the part. Before you ring the element, configure the tester: select the resistance measurement mode. Further:
- Attach the probes to the contacts. Standard values for a 20-degree temperature: 6000 Ohms.
- Heat the item in hot water. Pull it out, re-attach the probes and follow the changes on the tester screen. If everything is in order with the sensor, then the indicator at a 50-degree temperature will drop to about 1350 Ohms.
If you find a breakdown, then the part must be replaced. Choose a sensor that is suitable for the heater for your model of machine.
Important! The thermistor is not repairable. Do not attempt to disassemble or repair it.
Get gas-filled item
To remove the sensor with freon, you need to unscrew not only the back cover, but also the front panel with the control unit. This way you will have access to the outside of the thermostat.
Now proceed as follows:
- At the back of the washing machine housing you will find wiring. Carefully pull off the insulation and, using a thin spike, pick up the gasket covering the copper pipe to remove it.
- Now slightly press down the place of the base of the element so that it easily comes off the groove. A special hole is provided in the tank - remove the part through it.
- Remove the wire, and you can do the verification.
The main breakdown of sensors of this type is the failure of the tube with freon. A leak begins, and the element does not cope with its functions. If you find signs of leakage, you need to change accessories. Go to the nearest repair shop or order via the Internet a thermal sensor (with a switch), install instead of the old one. The assembly of the machine is carried out in the reverse way.
Replace bimetal part
Like a gas-filled, bimetallic sensor requires access to the tank. Having disassembled the body of the machine, disconnect the thermostat wiring and, using the tester, check the resistance. Warming up the sensor, follow the indicators again. In the absence of significant fluctuations, a replacement is needed.
Important! Bimetal sensors fail due to wear on the plate. But they are not subject to repair. Replacement is easy - get a suitable analogue and install instead of the old one.
What signs indicate a breakdown
In order to understand without understanding the SMA case that failures in its operation are associated with a temperature sensor, pay attention to the following symptoms:
- When choosing any program with any temperature regime, the water is heated to the maximum possible temperature (boils).
- When washing, the washer’s body heats up, and steam falls from the open hatch.
You can not delay! Damage to the sensor entails the output of their system heater. Changing both the heater and the sensor is more expensive and more complicated.
Replacing a thermostat of any type is quite possible with your own hands and without calling a wizard. The main thing is to correctly remove the part, find a high-quality and original analogue and connect it correctly.