--- title: "The moisture sensor and dryer sheets: why cycles end damp" description: "Softener film on two small metal strips can end an automatic cycle early; a wipe with alcohol usually fixes it." url: "https://dryerrepair.center/guides/moisture-sensor-and-dryer-sheets/" date_modified: "2026-09-25" --- Maintenance and prevention # The moisture sensor and dryer sheets: why cycles end damp A dryer moisture sensor is usually a pair of metal strips near the lint screen that read wetness when damp clothes touch them. Dryer sheets and softener leave a waxy film that insulates the strips, so sensor cycles end early with damp clothes. Wiping the bars with rubbing alcohol or mild soap every month or two usually restores normal drying. By [DryerRepair.center technical team](https://dryerrepair.center/authors/technical-team/) Published September 25, 2026 ## At a glance. Automatic cycles do not run on a timer. They stop when two small metal strips inside the drum stop feeling wet fabric, and the softener in a dryer sheet can coat those strips until the dryer believes a wet load is dry. Read the whole guide ### Where the strips are Inside the door opening, near the lint screen Two curved metal bars, sometimes on the rear drum wall instead. ### Main symptom of film Sensor cycles stop early, clothes still damp A timed cycle on the same load dries normally. ### Cleaner Rubbing alcohol or mild soap on a soft cloth Electrolux names alcohol; Samsung names mild soap. No abrasives. ### How often Every month or two with regular sheet use Less often if you use no sheets or softener. In this guide 1. How moisture sensing works 2. What dryer sheets leave behind 3. Cleaning the strips 4. When cleaning does not help 5. Less film going forward 6. Step by step 7. Questions ## How moisture sensing works Wet fabric conducts a small current; dry fabric barely does. Each time damp clothes tumble across the two strips, they bridge the gap, and the control counts those contacts. As the load dries, the contacts fade, and the dryer moves into its cool-down and ends. Samsung describes its sensor bars exactly this way, as strips inside the drum that stop the cycle once moisture is no longer detected. ENERGY STAR lists automatic termination among the features of certified dryers, because stopping on time saves energy and spares fabric from over-drying. LG calls the same part a humidity sensor and warns that a dirty one can lead to either too much or too little drying. ### Finding the strips on your dryer On most front-load dryers sold in the US, open the door and look at the lower front of the opening, just below or beside the lint screen: two curved, shiny strips set into the plastic. Some models mount them on the rear bulkhead at the back of the drum instead. On a stacked or compact dryer, a flashlight helps. ### Sensing on ventless dryers Heat-pump and condenser dryers use the same strips on many models, and some also read the humidity or temperature of the air leaving the drum. The film problem is the same on both designs, so the cleaning applies to ventless dryers too. Source: [Samsung — How to clean your Samsung dryer](https://www.samsung.com/us/support/answer/ANS10001019/) — Sensor Dry uses bars inside the drum that stop the cycle when moisture is no longer detected; clean them with a soft cloth and mild soap; [LG — How to clean the dryer humidity sensor](https://www.lg.com/us/support/help-library/lg-dryer-how-to-clean-the-humidity-sensor--20153089283667) — A contaminated humidity sensor can cause over-drying or incomplete drying; clean its surface regularly; [ENERGY STAR — Clothes dryers](https://www.energystar.gov/products/clothes_dryers) — Certified dryers use automatic termination; small loads can take longer to dry without the tumbling of a full load ## What dryer sheets leave behind A dryer sheet works by melting a thin layer of softening agent onto the load as it warms. Some of that coating lands on whatever else the clothes touch, including the drum, the lint screen and the sensor strips. Electrolux states that fabric softener sheets can leave a residue on the moisture sensor bars that keeps them from accurately sensing wet clothes. The film is nearly invisible. The strips may still look shiny, yet a fingertip drawn across them feels slightly greasy or tacky instead of clean metal. Liquid softener and heavy detergent carried over from the washer can add to the layer. - Loads come out damp after an automatic cycle but dry fine on a timed one. - Automatic cycles have become noticeably shorter than they used to be. - The display jumps to its cool-down stage a few minutes into a full load. - Heavy items, like jeans or towels, are dry on the surface but wet at the seams. Source: [Electrolux — Not drying and extended drying time](https://owner.electrolux.com/support-articles/article/1853008-my-dryer-takes-a-long-time-to-dry-a-load-of-clothes-can-i-do-anything-about-this-) — Softener sheets leave residue on the moisture sensor bars; wipe the bars with rubbing alcohol A hand wiping the two metal moisture sensor strips inside a dryer drum with a cloth. ## Cleaning the strips Manufacturers suggest slightly different cleaners. Electrolux says to wipe the bars with rubbing alcohol; Samsung says a soft cloth and mild soap, then dry them with a towel. Either works on ordinary film. Alcohol cuts heavy, waxy buildup faster, and it evaporates without leaving a trace. Scratches in the strips hold residue and speed the next buildup. Leave the door open for a while after using alcohol so the fumes clear before the dryer runs. A few things do more harm than good around the strips: - Scouring pads, steel wool or abrasive cleaning powder. - Spray cleaners that leave a scented or waxy coating of their own. - Soaking the area, since water can run down into the wiring below the strips. - Pliers or a screwdriver to pry at the strips, which are held by clips and wiring. Source: [Electrolux — Not drying and extended drying time](https://owner.electrolux.com/support-articles/article/1853008-my-dryer-takes-a-long-time-to-dry-a-load-of-clothes-can-i-do-anything-about-this-) — Softener sheets leave residue on the moisture sensor bars; wipe the bars with rubbing alcohol; [Samsung — How to clean your Samsung dryer](https://www.samsung.com/us/support/answer/ANS10001019/) — Sensor Dry uses bars inside the drum that stop the cycle when moisture is no longer detected; clean them with a soft cloth and mild soap ## When cleaning does not help Clean strips that still give short cycles, or cycles that never end, point somewhere else. ### Cycles that run far too long If an automatic cycle keeps going long after the clothes are dry, the strips are not the usual suspect. A blocked vent keeps the air in the drum humid; a wire from the strips that has broken or shorted can make the control read the load as permanently wet. Check the duct first, then book. ### Small loads fool it One shirt or a pair of socks rarely touches the strips, so the control has too little to go on. ENERGY STAR notes that small loads can take longer to dry without the tumbling effect of a full load. For a couple of items, a timed cycle is more reliable than a sensor cycle. ### The dryness setting Automatic cycles usually offer a dryness level, from damp through very dry. If someone set it to less dry, loads will feel damp with perfectly clean strips. Check the knob or the menu before assuming a part has failed. Source: [ENERGY STAR — Clothes dryers](https://www.energystar.gov/products/clothes_dryers) — Certified dryers use automatic termination; small loads can take longer to dry without the tumbling of a full load ## Less film going forward Using half a sheet, or a sheet only on synthetic loads where static is worst, cuts the buildup. Wool dryer balls soften without leaving a coating. Whatever you choose, pair it with a periodic wash of the lint screen, since the same residue closes up the mesh and slows airflow. A monthly wipe of the strips takes a minute, so it fits easily with the lint-screen wash. Households that use a sheet on every load are the ones most likely to see short cycles return within a couple of months. ## Where to stop Do not pull the front panel or unplug the sensor harness to chase a wiring problem: the harness shares space with the door switch and, on electric models, the heater wiring. If cleaned strips do not fix the cycle, leave the diagnosis to a technician with the dryer unplugged. Written by [DryerRepair.center technical team](https://dryerrepair.center/authors/technical-team/). The dryer technicians who handle the service appointments requested through this site. What they write starts with machines they have opened in laundry rooms and is set beside the manufacturer's installation and use instructions whenever those are available. Sources: [Electrolux — Not drying and extended drying time](https://owner.electrolux.com/support-articles/article/1853008-my-dryer-takes-a-long-time-to-dry-a-load-of-clothes-can-i-do-anything-about-this-) · [Samsung — How to clean your Samsung dryer](https://www.samsung.com/us/support/answer/ANS10001019/) · [LG — How to clean the dryer humidity sensor](https://www.lg.com/us/support/help-library/lg-dryer-how-to-clean-the-humidity-sensor--20153089283667) · [ENERGY STAR — Clothes dryers](https://www.energystar.gov/products/clothes_dryers) ## Step by step. Four steps, in the order worth doing them. 01 ### Unplug the dryer Unplug it or switch off the breaker, and let the drum cool if it has just run. 02 ### Find both strips Look at the lower front of the door opening near the lint screen, or at the rear wall of the drum. 03 ### Wipe with alcohol or soap Rub each strip firmly with a soft cloth dampened in rubbing alcohol, or in mild soap and water, until the metal feels clean. 04 ### Dry and air out Dry the strips with a towel, leave the door open for a while, then run a sensor cycle on a normal load. For the heart of your home. ## Questions owners ask. ### Are dryer sheets bad for my dryer? They do not harm the machine, but their residue coats the sensor strips and the lint screen. Clean both on a regular schedule if you use them. ### Can a dryer moisture sensor just wear out? The strips themselves rarely fail. Their wiring and the control that reads them can, and that shows up as cycles that end instantly or never end even after cleaning. ### Why do my clothes dry on the timed cycle but not on automatic? A timed cycle ignores the strips and simply runs for the set minutes. When only automatic cycles fall short, a coated sensor is the first thing to clean. ### Does fabric softener in the washer cause the same film? It can add to it, since some softener stays in the fabric and transfers in the dryer. Heavy use of either kind makes more frequent cleaning worthwhile. ## The problems behind it. Each has a page of its own: what it usually means and the causes in the order worth checking. [All 17 problems](https://dryerrepair.center/problems/) Problem ### Dryer Takes Too Long to Dry 5 causes, cheapest first Problem ### Dryer Stops Mid-Cycle 5 causes, cheapest first Problem ### Dryer Control Panel Not Responding 5 causes, cheapest first ## When it needs a technician. The repairs on the right are where this guide ends when the checks do not settle it. ### Controls and sensors A blank display, a panel that ignores buttons, codes, or cycles that end too soon or never end, traced to the board, timer or sensors. ### Diagnostic visit One visit that turns damp clothes, a silent drum or a hot smell into a named part and a price. ### Vent cleaning and inspection The visit that prevents most dryer fires and many of the repairs above it: the duct, the hood and the lint inside the cabinet. ## More in maintenance and prevention. The few habits that prevent most dryer calls, from the lint screen to the vent run, and how often each is worth doing. [The whole section](https://dryerrepair.center/guides/maintenance-and-prevention/) Keeping the dryer out of trouble ### Dryer vent cleaning schedule: screen, slot and duct Every load, every few months, once or twice a year, and the signs that mean the duct cannot wait for the calendar. Keeping the dryer out of trouble ### Belt and roller wear: what the thump and squeal mean The parts that carry and turn the drum wear by the hour, and each one makes a sound of its own before it quits. Guides ### All 18 guides Six sections, by what you are trying to find out. --- **[Read on the site: The moisture sensor and dryer sheets: why cycles end damp](https://dryerrepair.center/guides/moisture-sensor-and-dryer-sheets/)** **[Book a visit with DryerRepair.center](https://dryerrepair.center/schedule/)**