What is a Thermistor in a Dryer? (Explained)

A thermistor is a temperature-sensitive resistor that is used to measure the temperature in a clothes dryer. It works by signaling the dryer to make more or less heat based on how hot the air inside the drum is. So, it’s simply a heat sensor that monitors and regulates the air temperature inside the dryer.

Key Takeaways

  • A thermistor is a disk-shaped device usually located near the heating element and is used in many electronic devices, including clothes dryers.
  • It is used to monitor and regulate the air temperature inside the dryer drum.
  • If the air temperature gets too high, the thermistor will turn off the dryer to prevent the clothes from getting too hot.

Where is a thermistor located in a clothes dryer?

Most dryer models have a thermistor located in the air duct near the heating element or the blower assembly.

It checks the temperature of the air going through the duct and adjusts the heating element so that the temperature stays consistent.

The thermistor controls how much power goes to the heating element if the temperature becomes unstable or uneven.

For instance, if the element gets too hot, the thermistor will shut off the power to prevent the dryer from overheating.

The electrical wires running through the thermistors are connected to the main board or the control panel of the dryer on the other end.

How does the thermistor wear out?

Lint and dust can accumulate on the thermistor, causing premature wear-out.

Furthermore, clothes dryers use a lot of heat to dry your clothes, and the heat can eventually cause a thermistor to fail.

What happens if the thermistor wears out?

If the thermistor wears out, it may no longer be able to accurately monitor the air temperature inside the dryer, which can lead to overheating and cause damage to other components.

Additionally, this can damage your clothes and shorten the lifespan of your dryer

If a thermistor has worn out or has failed, you may need to replace it.

How to prevent thermistors from early wear-outs?

There are many variables that can affect the lifespan of your dryer’s thermistor, including how often and for how long you use it.

However, you can do a few things to prevent a premature thermistor failure in your dryer.

  • Make sure that the dryer is properly ventilated as it can have a big impact not only on the thermistors but also on other components of the dryer.
  • Always keep the lint screen clean and free of debris, doing this will prevent buildups in the venting system.
  • Additionally, you should inspect and clear any debris or lint from around the dryer’s heating element.
  • Do not overuse your dryer or run multiple cycles for a longer duration.

Keeping these simple tips in mind will help prevent thermistor failure in your dryer and keep most of the components running smoothly.

How to test a dryer thermistor?

In order to test a dryer thermistor, you will require a multimeter.

Once you have the multimeter handy you will need to set it to measure resistance.

Here’s how you can test the dryer thermistor.

Step 1: Disconnect from the power outlet 

Start by disconnecting the dryer from the power outlet and locating the thermistor.

It is most commonly located around the heating element or in the air ducts (check the user manual to confirm its exact location).

Step 2: Test it with Multimeter 

Grab a multimeter and touch one probe of the multimeter to one terminal of the thermistor and the second probe to the other terminal.

Next, make a note of the resistance reading on the multimeter.

While testing for faults, it’s important to note that most thermistors have a high Ohm value, which means they won’t register on the continuity test that easily.

So, it’s crucial that you compare the resistance reading to the thermistor’s specification.

The resistance reading should be within the stated range. If it is not, the thermistor may be defective and must be changed.

As long as the resistance readings fall within the prescribed range, the thermistor is working as it should.

How to replace a thermistor in the dryer?

To replace a broken or faulty thermistor, make sure to look at the user manual for your dryer’s type and model.

This will help you locate the thermistor and determine the correct part to replace (if you are replacing one).

Once you have read the manual and know where the thermistor is located, you can follow the below steps.

Step 1: Unplug the dryer

Start by unplugging the dryer from power, and you should do it as the first step before beginning.

Step 2: Remove the access panels

You may have to remove several outer panels of the dryer, such as the top, front, and back panels.

Accordingly, unscrew or unbolt to remove the panels and keep them aside.

Keep in mind that in order to remove the top panel, you must first remove the control panel.

As you remove the control panel, you may come across several electrical wires running through it.

Make sure to disconnect the wires carefully and label them accordingly, or simply take a picture of the fixtures.

Doing this will make it easy to reattach them later.

Also, you will need to gently pull the wire harness off the door switch to detach it.

Step 3: Remove the dryer’s drum

Once the access panels have been taken off, you can get to the dryer’s inside parts.

Most dryers have the thermistor at the bottom of the drum near the heating element.

It will require you to detach the duct housing and remove the drum first.

Start by taking out the screws that hold the mounting bracket to the blower assembly and the duct housing.

To take out the dryer’s drum, gently push the idler pulley until the dryer belt is no longer tight.

Now, carefully pull the belt off of the motor pulley to lift out the drum.

Step 4: Locate the thermistor to remove

Now, you will have access to the thermistor, which will be either a diamond-like or small disk-shaped device near the heating element.

Start by pressing the tabs to release the wire connector of the thermistor and taking out the mounting screw. You will now be able to pull the old thermistor out.

Step 5: Install the replacement thermistor

Place the new thermistor on the blower housing in the place where it should go. Now, secure it with the mounting screws and connect the wire harness.

Step 6: Reassemble the dryer

Finally, reassemble the dryer by reversing the steps. But be careful when you move the drum and connect the wires back to where they belong.

It is also a good idea to replace the worn-out or weaker screws that hold the dryer cabinets or access panels.

Additionally, as you reassemble the dryer, clean the internal areas.

Step 7: Plug in the dryer to run a test cycle

After you’ve finished taking the dryer apart and putting it back together, just plug it in and test it to make sure everything works.

Simply place a few damp garments in the dryer drum and run a test cycle to check if it is working like before.

Final Thoughts

The thermistor is a small sensor that monitors the air temperature inside the clothes dryer.

The dryer’s control panel uses the information from the thermistor to adjust the heating element so that the air inside the dryer stays at the correct temperature.

If a thermistor fails, your dryer may stop mid-cycle, necessitating replacement.

And if you are about to replace a broken thermistor, check the user manual for your dryer’s type and model.

Lastly, and most importantly, if you don’t know how to change the thermistor in your dryer, you can just call a service technician.

Manish Singh is an expert in electrical engineering with a Diploma in the field. With over 12 years of experience, he specializes in repairing music systems, washing machines, dryers, and other laundry-related appliances. His in-depth knowledge in electrical repairs and decent knowledge about garment care makes him a trusted authority in the field of appliance repair and laundry related topics. If you have any questions or need assistance with your appliances, you can reach out to Manish through email: manish.singh (at) portablelaundry.com