How do I know if my Whirlpool dryer thermistor is bad?

Signs of a bad Whirlpool dryer thermistor include the dryer running but not heating, clothes remaining damp, or the dryer overheating. If your multimeter readings show infinite resistance (OL) or deviate significantly from expected values at room temperature, the thermistor is likely faulty.

Can I bypass a broken Whirlpool dryer thermistor?

No, you should never bypass a Whirlpool dryer thermistor. It is a critical safety component that regulates temperature to prevent overheating and potential fires. Bypassing it is dangerous and can lead to severe damage to the dryer or a fire hazard.

Where is the thermistor located on a Whirlpool dryer?

The thermistor is typically located near the heating element or the blower housing on a Whirlpool dryer. You may need to remove the back or front access panel to locate it. Refer to your specific model's manual for precise location details.

What is the resistance of a good Whirlpool dryer thermistor?

A good Whirlpool dryer thermistor will generally have a resistance value between 10 kΩ and 50 kΩ (10,000-50,000 Ohms) at room temperature (around 70°F/21°C). However, the exact resistance varies by model, so consult your dryer's service manual for precise specifications.

How much does it cost to replace a Whirlpool dryer thermistor?

The cost to replace a Whirlpool dryer thermistor typically involves the part itself, which can range from $10 to $30, plus labor if you hire a technician. DIY replacement is very affordable if you only pay for the part.

Whirlpool Dryer Thermistor: What It Is and Why It Fails

What is a Whirlpool Dryer Thermistor?

A Whirlpool dryer thermistor is a small, electronic component vital for controlling the drying cycle's temperature. Also known as a temperature sensor or thermal resistor, it accurately measures the air temperature inside the dryer drum and sends this information to the dryer's control board. This feedback loop ensures the heating element cycles on and off appropriately, preventing overheating and ensuring clothes dry efficiently without damage.

Regulates dryer temperature for efficient drying.
Monitors air temperature, sending data to the control board.
Prevents overheating and potential fabric damage.
Key component for proper heating element function.

Without a functioning thermistor, your Whirlpool clothes dryer might fail to heat at all, overheat excessively, or shut off prematurely. Recognizing its importance is the first step in diagnosing and resolving common drying problems, especially those related to inconsistent or absent heat.

These components are designed to react to temperature changes by altering their electrical resistance. In a Whirlpool dryer, this resistance change is interpreted by the main control unit, which then makes decisions about whether to activate or deactivate the heating element and fan. This dynamic adjustment is what allows for different heat settings and prevents the dryer from becoming a fire hazard.

Why Your Whirlpool Dryer Might Not Be Heating

When a Whirlpool dryer fails to heat, the thermistor is one of the prime suspects, often alongside the heating element itself, thermal fuses, or the cycling thermostat. A faulty thermistor can send incorrect temperature readings, tricking the control board into thinking the drum is already hot enough, or conversely, that it's too cold and needs continuous heating, leading to damage.

Symptoms of a failing Whirlpool dryer thermistor can vary. You might notice that the dryer runs but produces no heat, leading to damp clothes after a full cycle. Conversely, it might overheat, making the dryer excessively hot to the touch and potentially damaging delicate fabrics. Some thermistor failures cause the dryer to run for a short period and then shut off unexpectedly, or to cycle between heating and cooling erratically.

The thermistor is a critical gatekeeper for your dryer's heating system. If it fails to accurately report the drum's temperature, the control board cannot make informed decisions, leading to the exact opposite of what you want: clothes that are still wet or damaged.

Common Failure Scenarios for a Dryer Thermistor

Open Circuit: The thermistor stops conducting electricity entirely, telling the control board the temperature is always extremely high, thus preventing heat from engaging.
Short Circuit: The thermistor's resistance drops to near zero, signaling a very low temperature, which might cause the heating element to run constantly, leading to overheating.
Drifted Resistance: Over time, the thermistor's resistance value may drift outside its specified range, causing inaccurate temperature readings and unreliable heating cycles.

While the thermistor itself is generally robust, it can fail due to age, prolonged exposure to extreme temperatures, or electrical surges. It's important to test the thermistor, along with other heating circuit components, when troubleshooting a Whirlpool clothes dryer that's not heating correctly. This methodical approach ensures you replace only the faulty part.

How to Test a Whirlpool Dryer Thermistor

Before replacing parts, you must properly test the Whirlpool dryer thermistor to confirm it's the source of the problem. This process requires basic tools like a multimeter and a bit of technical understanding. Always disconnect power to the dryer before beginning any internal inspection or testing to avoid electrical shock.

Step-by-Step Testing Procedure

Access the Thermistor: Consult your dryer's service manual or look for online guides specific to your Whirlpool model (e.g., Whirlpool Cabrio dryer, Whirlpool Duet dryer) to locate the thermistor. It's typically found near the heating element or blower housing.
Disconnect Wires: Carefully remove the wires connected to the thermistor terminals. Note their positions or take a photo to ensure correct reattachment later.
Set Multimeter: Configure your multimeter to measure resistance (Ohms or Ω).
Test at Room Temperature: Place the multimeter probes onto the thermistor's terminals. At room temperature (around 70°F or 21°C), a good thermistor will typically show a resistance value between 10 kΩ and 50 kΩ (10,000 to 50,000 Ohms), but the exact value depends on the specific Whirlpool dryer model and the thermistor's specifications. Check your dryer's manual for the precise expected resistance.
Test with Heat (Optional but Recommended): To further verify, gently warm the thermistor with a hairdryer (do not overheat). As it warms, the resistance should decrease. If the resistance doesn't change or changes erratically, the thermistor is likely faulty.
Check for Continuity: Test for continuity by setting the multimeter to the lowest Ohm setting. A good thermistor should show resistance. If the multimeter reads infinite resistance (OL) at room temperature, it indicates an open circuit, meaning the thermistor is bad.

Test all components in the heating circuit, including thermal fuses and the cycling thermostat, as they can also cause a Whirlpool dryer not to heat.

If your multimeter readings are significantly different from the manufacturer's specifications or show no continuity (indicating an open circuit), the thermistor needs replacement. For models like the Whirlpool WED4815EW1 or the Whirlpool Duet Steam Dryer, this testing method is generally applicable.

Replacing a Whirlpool Dryer Thermistor

Replacing a faulty Whirlpool dryer thermistor is a manageable DIY repair if you are comfortable with basic appliance disassembly and electrical testing. The process involves accessing the component, removing the old one, and installing the new part. Always refer to your specific Whirlpool model's manual for exact instructions and part numbers.

Locating and Replacing the Part

Identify the Correct Replacement Part: Use your dryer's model number to find the precise OEM (Original Equipment Manufacturer) thermistor or a compatible aftermarket part. Online appliance parts retailers can assist with this, often requiring the model number for accuracy.
Gain Access: After unplugging the dryer, you'll need to remove panels to reach the thermistor. This might involve taking off the back panel, front panel, or sometimes accessing it from underneath.
Remove Old Thermistor: Once visible, detach any mounting screws or clips holding the thermistor in place. Carefully disconnect the wires attached to its terminals.
Install New Thermistor: Connect the wires to the new thermistor, ensuring they go to the correct terminals. Secure the new thermistor in its mounting position.
Reassemble Dryer: Replace all panels and screws, ensuring everything is secure.
Test the Repair: Plug the dryer back in and run a cycle to check if the heating issue is resolved.

Never attempt to bypass or omit the thermistor; doing so removes a critical safety feature and can lead to serious damage or fire hazards. If you're unsure about any step or uncomfortable working with electrical components, it's best to consult a qualified appliance repair technician.

For Whirlpool Estate Dryer models or older Whirlpool dryers, the general principles remain the same, though the exact panel removal and component location might differ. If comparing Maytag vs. Whirlpool dryer repairs, you'll find many internal components, including thermistors, are shared or function on similar principles due to common manufacturing. Always ensure you have the correct part number for your specific appliance.

When to Call a Professional

While replacing a Whirlpool dryer thermistor can be a DIY task, several situations warrant calling a professional appliance repair technician. If you're hesitant about performing the diagnostic tests, uncomfortable disassembling your appliance, or if the problem persists after replacing the thermistor, it's time to seek expert help.

Complex electrical issues, problems with the control board itself, or persistent heating problems that aren't resolved by replacing common components like the thermistor, heating element, or thermal fuse, often require specialized knowledge and tools. A technician can perform a more thorough diagnosis, check wiring diagrams for issues, and ensure all safety features are functioning correctly.

Consider professional service if your dryer is still under warranty, as DIY repairs might void it. Additionally, if you've performed the tests and are still unsure about the diagnosis, a technician can quickly pinpoint the issue and provide a reliable solution.

It's also worth noting that while appliance repair can be cost-effective compared to buying a new dryer, getting an estimate from a professional can help you weigh the repair cost against the appliance's age and overall condition. For older Whirlpool models or if you've experienced repeated issues, a professional can advise on the long-term viability of the repair.