Why your dryer's moisture sensor fails in summer—and how to restore it

What a moisture sensor does (and why summer breaks it)

Modern dryers use moisture sensors instead of timers to detect when clothes are actually dry. Two metal bars inside the drum touch your laundry; when moisture evaporates, electrical resistance changes and the dryer stops. In theory, this saves energy and prevents over-drying.

But in Metro Vancouver's humid summers, lint and mineral deposits build up on those sensor bars. Once coated, they can't sense moisture accurately—so your dryer thinks clothes are still wet when they're bone-dry. The result: cycles that run 20, 30, even 45 minutes longer than necessary.

Port Coquitlam residents notice this most in August, when outdoor humidity peaks and laundry days get busier.

How to find and inspect your sensors

Moisture sensors are almost always located inside the dryer drum, near the front. On most machines, you'll see two small metal bars protruding slightly into the drum—they look like little rails or tabs.

Unplug the dryer and open the door. Look for these bars on either the right or left side of the drum's interior (the exact location varies by brand). Run your fingernail gently across them. If they feel rough, gritty, or have a chalky film, they need cleaning.

The simple fix: clean the sensors

Unplug the dryer and let it cool for 15 minutes. Use a soft, lint-free cloth—microfibre works well—and gently wipe each sensor bar. Wipe lengthwise along the bar, not across it. This removes loose lint and dust.

For stubborn mineral deposits (common in Lower Mainland water), dampen the cloth with white vinegar and wipe again. Let the vinegar dry completely before plugging the dryer back in. This usually takes 10–15 minutes.

Run a test cycle on a damp hand towel. If the dryer shuts off when the towel is still slightly damp, the sensors are working again. If cycles still run long, the sensor bars may be damaged or the sensor circuit may have failed.

When cleaning isn't enough

If you've cleaned the sensors and drying times haven't improved, the sensor itself may be faulty. Moisture sensors typically cost $80–$200 to replace, depending on your dryer model. A technician can test the sensor's electrical resistance to confirm failure.

In the meantime, you can use your dryer's timed-dry setting on low heat for delicate fabrics, though you'll need to monitor cycles manually. Most Port Coquitlam homes with older dryers benefit from a professional inspection every 2–3 years, especially if they run loads frequently during summer.

Prevention in humid months

During August and early September, inspect sensors monthly. Wipe them dry after every 10–15 loads. Clean the lint trap before each cycle—a clogged trap reduces airflow and makes sensors work harder to detect moisture.

If your dryer vents to the outside, check that the exterior vent hood isn't blocked by dust or insects. Restricted venting forces the dryer to run longer, and sensors become less reliable under stress.