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The temperature sensor in the design of the washing machine is responsible for the correct heating of water according to the specified parameters and turning off the heater when necessary. And if the washing machine has stopped heating the water or overheats it, then the heat-sensitive element may be the culprit.
Checking and replacing the temperature sensor in the washing machine is the topic of our article. Useful tips, step-by-step instructions and recommendations are waiting for you.
What are the sensors
Any of three possible types of sensors can be provided in the SMA:
- gas-filled;
- bimetallic;
- thermistor.
Each of these types has its own principle of operation and its own features of performance testing and replacement.
Gas-filled sensor
Its design has 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 inside of the tank, in direct contact with water – this is how its temperature is measured. Inside such a sensor, a gas circulates, known to everyone as freon (used in refrigerators). When exposed to temperature, the gas contracts and expands, opening and closing the contacts connected to the heating element.
Bimetal sensor
This is a part of 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 heating when the set temperature is reached.
thermistor
Such a temperature sensor is installed in all the latest models of machines. If your CM is no more than 7 years old, it will most likely have the same element in it. It looks like a small cylinder with a diameter of up to 1 cm and a length of up to 3 cm. It is distinguished from the previous ones by the type of fastening – it is installed on the heater itself. The sensor does not work according to a mechanical principle, but due to resistance fluctuations during water heating.
How to check and replace the temperature sensor
Before you check the performance of the sensitive element, you need to slightly disassemble the body of the machine. Your task is to disassemble the housing and remove the thermostat from the heater: this way you will make it easier for yourself to check. In 4 machines out of 5, the heating element and the thermistor are located under the tank, so it is not difficult to get close to it. Before removing the sensor:
- Open the back of the washing machine by unscrewing the 4 or 5 bolts around the perimeter of the cover.
- Remove the wiring connecting the element to the control board. Take a photo or mark the wires so that you can reassemble everything as it was.
- Loosen the heater fixing – the retaining nut is exactly in the center.
Now remove the thermostat. After taking out the sensor, you need to check it with a multimeter and measure the resistance of the part. Before ringing the element, set up the tester: select the resistance measurement mode. Further:
- Attach the probes to the contacts. Standard indicators for a 20-degree temperature: 6000 ohms.
- Heat the element in hot water. Pull it out, reattach the probes and watch 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 suitable for the heating element of your model of the machine.
Important! The thermistor is beyond repair. Do not attempt to disassemble or repair it.
Get the gas-filled element
To remove the freon sensor, you need to unscrew not only the back cover, but also the front panel with the control unit. This will give you access to the outside of the thermostat.
Now act like this:
- You will find the wiring on the back of the washing machine body. Carefully pull off the insulation and, using a thin spike, pry the seal around the copper tube to remove it.
- Now press down a little on 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’re good to go.
The main failure 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 the components. Go to the nearest repair shop or order a temperature sensor (with a switch) via the Internet, install instead of the old one. The machine is assembled in reverse order.
Replace bimetal piece
Like the gas-filled one, the bimetal sensor requires access to the tank. After disassembling the body of the machine, disconnect the thermostat wiring and, using a tester, check the resistance. Warming up the sensor, monitor the indicators again. In the absence of significant fluctuations, a replacement is necessary.
Important! Bimetal sensors fail due to plate wear. But they are not repairable. Replacement is easy – purchase a suitable analogue and install instead of the old one.
What are the signs of a breakdown?
In order to understand without disassembling the CMA case that failures in its operation are associated with a temperature sensor, pay attention to the following signs:
- When choosing any program with any temperature mode, the water is heated to the maximum possible temperature (boils).
- When washing, the body of the washer heats up, and steam comes out of the open hatch.
You can’t delay! Failure of the sensor entails the failure of their heater system. Changing both the heating element and the sensor is more expensive and more difficult.
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.