Do you know how to test dryer thermistor? From my experience, it’s one of the easiest ways to diagnose heating problems in your dryer. The thermistor is a small part with a big job—it tracks the heat inside your dryer and helps control the temperature.
Knowing how to test it can save you from longer drying times or even more serious issues. By using a multimeter to measure its resistance, you’ll quickly know if it’s working properly or needs to be replaced.
A Quick Look
A thermistor is a type of resistor whose resistance changes significantly with temperature. It’s commonly used in temperature sensing or control applications due to its high sensitivity to temperature changes.
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It works by changing resistance based on temperature. When the temperature goes up, the resistance drops, which tells the dryer to adjust the heat. In Whirlpool dryers, error codes like F-22 or F-23 often signal thermistor failure, so it’s important to check it right away.
Quick Fix: How to Test a Dryer Thermistor
Testing a dryer thermistor is simple and helps diagnose heating issues. First, unplug the dryer for safety and locate the thermistor near the blower housing. Use a multimeter set to resistance mode; at room temperature, it should read around 11,000 ohms.
Heat it gently, and the reading should drop to about 8,500 ohms at 100°F (38°C). If the readings are incorrect, the thermistor likely needs replacing. Following these steps can prevent longer drying times and costly repairs!
What are common signs of faulty thermistors?
If your dryer displays error codes like F-22 or F-23, experiences longer drying times (up to 30% more), or overheats, the thermistor may be malfunctioning. Inconsistent heating is another common sign.
To fix the issue, it’s important to know how to test a thermistor and check if it needs replacement.
Technical Considerations for Testing a Dryer Thermistor
If you want to learn how to test dryer thermistor, You must have to follow these important considerations;
- Turn Off Power: Disconnect the dryer from the power source for safety.
- Locate the Thermistor: Refer to the manual for its position, usually near the heating element.
- Use a Multimeter: Set it to the resistance (ohms) setting to measure the thermistor’s resistance.
- Check Resistance Values: Compare readings to the manufacturer’s specifications; resistance should decrease with temperature.
- Inspect for Damage: Look for signs of wear or corrosion on the thermistor and connections.
- Reinstall Carefully: Properly reinstall the thermistor and reconnect any wires before restoring power.
Tools You’ll Need
- Multimeter: Use a manual multimeter set to 20K ohms or an automatic one to check the thermistor’s resistance.
- Screwdriver: Needed to remove the back panel of the dryer and access the thermistor.
- Safety First: Always unplug the dryer before starting to avoid electrical shock.
- Replacement Thermistor: For dryers, check the thermistor part number such as WP8577274, and it works with several other brands too.
How to Test Dryer Thermistor| Step-by-Step Guide with a Multimeter
Step 1: Unplug the Dryer
First things first, always unplug your dryer to avoid any risk of electrical shock. Safety comes first whenever you’re working with electrical appliances.
Step 2: Locate the Thermistor
In most dryers, the thermistor is located near the blower housing or exhaust vent. To access it, you’ll need a screwdriver to remove 3-5 screws holding the back panel in place. Once you’ve removed the panel, you’ll spot the thermistor—it’s a small flat plate with two wires attached to it.
Step 3: Set Up Your Multimeter
Next, grab your multimeter. If you have a manual one, set it to 20K ohms to test resistance. If it’s an automatic multimeter, you don’t need to adjust any settings—it will auto-detect the proper range.
Step 4: Test the Thermistor at Room Temperature
With the multimeter probes in hand, place them on the thermistor’s two terminals. At room temperature (around 70°F or 21°C), the resistance should read roughly 11,000 ohms. If your reading is significantly higher or lower, the thermistor might be bad and may need replacement.
Troubleshooting Common Thermistor Testing Problems
Testing a dryer thermistor doesn’t always go smoothly, but don’t worry—there are a few common issues and easy fixes.
1- No Reading on the Multimeter
If your multimeter shows no reading at all, check that the probes are connected to the thermistor terminals properly. If everything is connected but still no reading, the thermistor is likely shorted or open-circuit and needs to be replaced.
2- Inconsistent Resistance Readings
Inconsistent readings can sometimes happen if the thermistor’s terminals are dirty. I’ve had success cleaning them with a bit of isopropyl alcohol. After cleaning, retest the thermistor to see if the reading stabilizes.
3. No Change in Resistance During Heat Test
When you heat the thermistor with a hairdryer and there’s no change in resistance (or the change is too small), it’s a clear sign that the thermistor is faulty. As mentioned earlier, the resistance should drop to about 8,500 ohms at 100°F (38°C).
If you run into these problems, don’t panic! It’s all part of the process, and replacing a faulty thermistor is a quick fix once identified.
How to Replace a Faulty Thermistor
If you’ve followed the steps on how to test dryer thermistor and confirmed it’s faulty, replacing it is actually pretty simple. Here’s how I do it:
Step 1: Buy the Right Thermistor
For dryers, you’ll need a part number such as WP8577274. Make sure you get the right one because using the wrong part can cause more problems. Most replacement thermistors cost around $20-$30, depending on the brand.
Step 2: Remove the Old Thermistor
First, unplug your dryer. Then, using a screwdriver, unscrew and remove the faulty thermistor. It’s usually attached with 2-3 screws. Disconnect the wires, making sure to note where they attach so you can connect the new one correctly.
Step 3: Install the New Thermistor
Attach the wires to the new thermistor and secure it in place with the screws you removed earlier. Double-check that everything is connected properly before putting the back panel on.
Step 4: Test the Dryer
Once the new thermistor is in place, plug in the dryer and run a short test cycle. If everything works correctly, your dryer should heat and run as expected without any error codes.
Replacing a thermistor is something you can do yourself with just a few tools, saving you both time and money.
Safety Guidelines for Testing and Replacing a Dryer Thermistor
When you’re learning how to test a dryer thermistor, safety should always be your first concern. Working with electrical appliances can be risky, but with these simple guidelines, you can stay safe.
- Unplug the Dryer
Always unplug the dryer before working on it. This is the most important safety step to prevent electric shock. - Wear Protective Gear
It’s a good idea to wear gloves and safety glasses. The thermistor is located near other components, and having protective gear can shield you from any loose parts or sharp edges. - Use a Multimeter Safely
Make sure your multimeter is set to the correct setting (usually 20K ohms) to avoid damaging the tool or getting inaccurate readings. - Handle Electrical Components Carefully
When disconnecting or reconnecting wires to the thermistor, always hold the wires by the connectors. Pulling on the wires themselves can damage them, which could cause more problems. - Avoid Working in Wet Conditions
Never work on your dryer in a damp or wet environment. Water and electricity don’t mix, and this could result in a serious shock.
By following these safety guidelines, you can safely test or replace your dryer thermistor without any issues.
Call to A Professional
If you’re unsure about the dryer thermistor or if you encounter issues, it’s best to consult a professional. A certified technician can accurately diagnose and fix any problems, ensuring your dryer operates safely and efficiently. Don’t hesitate to reach out for expert help!
Conclusion
Testing a dryer thermistor is simpler than it might seem. By following the proper steps, using the right tools like a multimeter, and keeping safety in mind, you can save yourself time and money. Whether it’s troubleshooting overheating issues or fixing error codes like F-22, having the knowledge on how to test dryer thermistors puts you in control of your dryer’s performance. With regular maintenance and these easy steps, your dryer will stay in great shape for years to come.
FAQ’s
- What causes a thermistor to fail?
From my experience, most thermistors fail due to overheating or lint buildup, which affects the airflow and makes the dryer work harder than necessary. - Can I bypass a faulty thermistor?
It’s not safe to bypass a thermistor. The thermistor is there to regulate heat, and bypassing it could lead to overheating, causing damage or even a fire hazard.
How often should I test the dryer thermistor?
It’s a good idea to test the dryer thermistor once a year or if you notice issues like longer drying times, overheating, or error codes like F-22 or F-23.
