Is your gas or electric dryer not drying clothes as expected, often leaving a load damp even after a full cycle? This common frustration might stem from a small but critical component: the moisture sensor. At Repair Clinic, we provide straightforward troubleshooting steps to check whether your moisture sensor is functioning optimally, along with testing methods to ensure it’s operational. Before diving into these steps, let’s understand how the moisture sensor should work and why it’s essential for your dryer’s performance. If you discover that you need a replacement, browse our extensive selection of dryer parts tailored to fit your specific model.
How does a dryer moisture sensor work?
A dryer moisture sensor, also known as a dryer humidity sensor, is a component that measures the level of moisture or humidity inside the dryer drum. The sensor affects dryer operation by determining when the laundry inside the dryer is sufficiently dry and to signal the appliance to stop the drying cycle. A dryer moisture sensor detects the level of moisture in the clothes during a drying cycle by measuring the electrical conductivity of the clothes. Wet clothes conduct electricity better than dry ones, and this change in conductivity influences the dryer’s drying cycle. While the dryer moisture sensor location and exact implementation of a moisture sensor may vary depending on the dryer model, the underlying principle of how it works is generally the same.
Where is the dryer moisture sensor located in my dryer?
The moisture sensor is typically located on the lint filter housing grille or the rear bulkhead of the dryer. This positioning allows the tumbling laundry to make regular contact with the sensor, facilitating accurate moisture detection. A dryer moisture sensor looks like a pair of metallic bars mounted in a plastic housing. This positioning allows the tumbling laundry to make regular contact with the sensor, facilitating accurate moisture detection.
Wet clothes conduct electricity better than dry clothes
The moisture sensor relies on the fact that wet clothes conduct electricity better than dry clothes. When wet clothes come into contact with the sensor, they create a conductive path between the two sensor elements (the metallic bars). The moisture sensor periodically sends a small electrical current across its sensor elements. If the clothes are wet, the current will flow through the clothes, completing the circuit and allowing the electricity to pass through.
The moisture sensor measures the resistance of the electrical circuit
The moisture sensor measures the resistance of the electrical circuit formed by the wet clothes and the sensor elements. Wet clothes have lower resistance, as they provide a better conductive path, whereas dry clothes have higher resistance. The moisture sensor compares the measured resistance to a predetermined threshold value. The threshold represents the desired moisture level in the clothes. If the resistance is above the threshold, it indicates that the clothes are dry or nearing dryness, and the drying cycle can be stopped.
The sensor assists the control in determining if the drying cycle should continue or stop
Based on the moisture sensor’s readings, the dryer’s control system determines whether to continue the drying cycle or to stop it. If the measured resistance falls below the threshold, indicating that the laundry is still wet, the dryer will continue the drying process. However, if the resistance remains above the threshold, the dryer will stop the cycle, assuming the laundry is sufficiently dry. By using a moisture sensor, the dryer can automatically adjust the drying time based on the actual moisture content of the laundry. This ensures the clothes, towels, or linens are adequately dried, but it also helps prevent over-drying, which can damage the fabric and waste energy.
How do you know if your dryer moisture sensor is bad?
If your laundry is consistently damp after a full drying cycle, or if the dryer stops before clothes are dry, the moisture sensor might be malfunctioning. Testing the sensor with a multimeter or checking for visible residue or damage can confirm if the sensor is not working correctly.
Have you been finding the laundry is not drying efficiently? The moisture sensor may be unable to accurately detect the amount of moisture in the load. This can happen when residue builds up on the sensor bars, something that can happen over time if dryer sheets are used regularly to eliminate static cling and add a fresh scent. One or both of the sensor bars could be broken as well, or a wire connection could be damaged or loose.
If the dryer isn’t stopping when expected, it’s possible the sensor bars have shorted by coming into contact with each other. There is a simple test you can perform using a multimeter that will help you troubleshoot a moisture sensor to determine if the part is malfunctioning or not.
What should I do if my dryer moisture sensor is not working?
If the dryer sensor is not working, first try cleaning the sensor bars with a light vinegar solution to remove any residue. If the sensor still fails the multimeter test after cleaning, it may need to be replaced. Detailed instructions for replacing the sensor can often be found in your dryer’s manual or manufacturer’s website.
How can I test a dryer moisture sensor with a multimeter?
You won’t need the dryer to be running to perform the test, so make sure the appliance is turned off and there’s no laundry in the drum. Now, here’s how you can check the moisture sensor:
- To test the dryer moisture sensor with a multimeter, set the multimeter to measure ohms of resistance at a high setting (the high setting is required to get an electrical continuity reading for most moisture sensors).
- Place one meter lead on each of the sensor bars. Contact the black meter lead to one of the sensor bars and the red lead to the other bar. If the meter display shows that ohms of resistance are present, you’ll know the sensor has shorted and the component will need to be replaced.
- Keeping the meter leads on the bars, apply a wet cloth across both bars. The meter display should show the ohms of resistance changing. A change in resistance when a wet cloth is applied to the sensor bars indicates the sensor is functioning properly.
- If the resistance doesn’t change, the sensor might need cleaning or replacement. It’s possible the bars have become coated with dryer sheet residue and are unable to accurately detect the moisture. Clean the bars with a light vinegar solution and repeat the test. If the resistance doesn’t change, the sensor might need cleaning or replacement.
More dryer repair help from Repair Clinic
Need to know the correct way to install a new moisture sensor on an LG electric dryer (model DLEX4000B)? What about replacing a single moisture sensor bar on the model DV405ETPAWR Samsung electric dryer? Repair Clinic has model-specific part replacement videos to take you through the entire procedure step-by-step. You’ll find these, plus hundreds of other gas and electric dryer repair videos, guides, and schematics in the “Videos & Articles” section of the Repair Clinic website. This is another way Repair Clinic supports technicians and DIYers alike with the necessary know-how to repair all major home appliances, outdoor power equipment, and heating and cooling systems.
Repair Clinic has the right moisture sensor for your dryer
Once you know how to replace that moisture sensor, you’re going to want to make sure you’re installing the right sensor that’s compatible with the dryer model. Repair Clinic makes this part easy. Just enter the full model number of the dryer in the Repair Clinic website search bar, choose “Sensor & Thermistor” using the “Part Category” navigation filter followed by “Moisture Sensor” using the “Part Title” navigation filter. You’ll be shown the exact original manufacturer equipment moisture sensor that works with the dryer you’re fixing, including those built by Whirlpool, Electrolux, Kenmore, GE, Maytag, LG, and Samsung. With Repair Clinic as your repair partner, you’ll save both time and money with every repair.