How to check the temperature sensor for serviceability in a washing machine

One possible cause of improperly heated water in your washing machine could be a malfunctioning temperature sensor. This tiny part is essential to regulating the water’s temperature during a washing cycle and guaranteeing that your clothes get a thorough cleaning.

The temperature sensor may deteriorate or stop working over time, resulting in problems like overheating or cold washes. It is possible to check the sensor yourself to see if it is still functional before bringing in a repair technician.

We’ll walk you through easy temperature sensor testing procedures in this guide, so you can assess whether the sensor needs to be replaced or if there’s another problem at hand.

Where is the thermostat located and how it works

The thermistor is situated in the heating element of the majority of washing machine models. It is cylindrical in shape and has a 10 mm circumference diameter.

The thermistor, which takes the shape of a tablet with a diameter of 25–30 mm, can be installed independently of the heater in certain washing machines and placed directly in the tank in the location designated by the design.

To measure the liquid’s current temperature, one portion of it comes into direct contact with the water in the tank. Wires that carry readings from the electronic component to the electronic unit are connected to the sensor’s second, external component.

Electronic temperature sensors send resistance readings, which vary based on the water’s heating level, as well as other data to the control unit. The processor manages the heater’s timely shutdown by converting the resistance readings from the sensors into temperature parameters.

Gas thermostats were used in older machines. They were constructed as a thin metal tube filled with gas, with a temperature regulator on one side and a tip in contact with water on the other.

A change in pressure during the heating of the water caused the power supply to the heating element in such a sensor to be disconnected. These thermostats were eventually superseded by their electronic equivalents, which are the least expensive and have a simpler design.

How to check the temperature sensor of the washing machine

If the washing machine begins to act strangely, specifically:

• It takes a long time to wash;
• When touched by hand during washing, the hatch glass remains cold or very hot (not according to the set temperature);
• The program fails, some error code appears on the display;
• After washing, poor quality of dirt removal is detected;
  then you need to check the thermostat for proper operation;
• To do this, you will need to determine where it is located. It is best to dismantle it from the installation site and check it outside the machine.

While the method varies amongst washing machine models, the general idea remains the same:

• LG machine. Remove the back cover of the product body. The temperature sensor in the LG washing machine is located either in the heater itself or in the tank to the left of the heating element. To remove it from the heating element, you need to loosen the spiral fastening nut, remove the wires from the thermostat and pull it towards you. Switch the multimeter to measure resistance on the 200 kOhm scale. Make measurements at room temperature. Touch the sensor contacts with the probes. The resistance should be approximately 50 kOhm.
• After this, do not remove the probes from the contacts, lower the sensor into preheated water. The resistance of the sensor should change smoothly without fragments of readings on the tester screen (readings should not disappear). If the readings disappear or are not there at all, then the sensor must be replaced with a new one;

• Indesit washing machine. Remove the back cover of the machine. The sensor is in the heater. Loosen the heating element fastening and remove the sensor from it, having previously disconnected the wiring from it.
• The readings of a serviceable sensor at room temperature are approximately 20 kOhm. When it is heated in hot water, the readings will decrease;
• Bosch washing machine.

To access the thermostat, you have to:

1. Remove the tray for powder, unscrew the self -tapping screw in its niche;
2. Then open the inspection window of the pump filter, unscrew the screw securing the false panel;
3. Move the false panel to the right and then towards you;
4. Unscrew 2-4 screws securing the front removable part of the housing underneath it;
5. Open the hatch and remove the outer clamp of the cuff, tuck the rubber itself inside the housing;
6. Take the lower part of the front panel away from the housing by a couple of centimeters and pull it down, it will come off the guides. All that remains is to disconnect the wires from the blocker lock;
7. The lower front part of the tank will show the heating element of the machine with a sensor inside;
8. Loosen the fastening of the heater and remove the thermistor. Its normal resistance will be equal to 6.2 vOhm. If the readings differ significantly from the nominal value, then the temperature sensor in the washing machine needs to be replaced;
9. Candy washing machine. The temperature sensor in products of this brand has the shape of a tablet and is located in the back of the tank outside the heater. Its normal resistance is 20 kOhm, when heated, the indications must be reduced;
10. Samsung products. In these washing machines, the sensor we are describing is located in the front of the machine, installed in the heating element.

The temperature controller itself, a freon-filled tube, and a limit switch are examples of obsolete sensors that can be examined in the manner described below:

• Set the controller to the "0" position;
• Heat the water, for example, to a temperature of 50 degrees;
• Move the controller to the 45-48 degree position and lower the sensor limit switch into the heated water.
• In this case, after a few seconds, a slight click will sound in the controller, and the heating element power supply circuit will be broken at the controller contacts.
• When checking, you can connect the tester probes to the controller contacts, and switch the multimeter itself to the "bell".

The washing machine temperature sensor still needs to be replaced even if it hasn’t failed entirely and just doesn’t match the required readings.

The control module’s processor regulates the water’s heating temperature while it is being washed by looking at its resistance values.

If you wash your items in cold water, incorrect thermistor readings will cause damage from increased heat treatment, or at the very least, poor stain removal.

A multimeter can be used to measure the resistance of the temperature sensor in a washing machine. When a sensor is operating correctly, it will display a particular resistance range that varies with temperature. The sensor may be defective and needs to be replaced if the readings are incorrect or don’t change with temperature.

How to ring a heating element with a multimeter

It is required to use a multimeter to examine the heating element if the temperature sensor readings were found to be accurate during the checkup and the washing machine is still using cold water. Using a tester to inspect the heating element is fairly simple; just disconnect the wires, turn on the multimeter to find the lowest resistance, and use the probes to ring the heater’s contacts.

The water heater’s resistance ought to be between 25 and 35 Ohm. Following that, it’s imperative to look for any potential case breakdowns.

To accomplish this, set the multimeter to the highest resistance measurement values, touch any part contact with one probe, and touch the part’s case with the other.

The resistance on the tester will be equal to one when the housing is intact. Before checking the heating element for case breakdown, it must be submerged in water for a while; otherwise, a dry heater may produce positive measurement results.

For the washing machine to function normally and to protect users from electric shock damage, a malfunctioning heater needs to be replaced. The majority of contemporary washing machines turn off the program when they detect a breakdown on the washing machine casing.

Additionally, in the event that the washing machine’s power supply circuit contains an RCD, this device will totally de-energize the socket at the first sign of an electrical failure on the product case. Using electrical appliances in poorly ventilated rooms or in environments with high humidity can also cause this.

By checking the temperature sensor in your washing machine, you can prevent more serious issues down the road by spotting malfunctions early on. The sensor is a good place to start if your washer isn’t heating water correctly or isn’t providing error codes.

You can find out if the sensor is operating as it should by doing a few easy steps, such as measuring the resistance of the sensor with a multimeter. Replacing the sensor is frequently a simple solution that can bring your machine back to optimal performance if the readings are off.

Maintaining the longevity and optimal performance of your washing machine is possible by routinely inspecting important parts such as the temperature sensor. A little work now can save a lot of money on frustration and repair expenses.

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