Dryer taking too long to dry clothes — San Francisco, California

When a dryer runs a full cycle but clothes come out still damp, the problem is almost always restricted airflow or a failing heat source. The most common culprit is a clogged vent duct: lint builds up beyond the lint trap — inside the duct, at the elbow, or at the exterior flap — and chokes exhaust flow. This is also a fire hazard: clogged dryer vents cause an estimated 2,900 house fires per year in the U.S. A kinked or crushed flexible duct behind the dryer has the same effect. On the mechanical side, a burned-out heating element (electric) or a faulty gas igniter/flame sensor (gas) means the drum tumbles but never reaches drying temperature. Worn felt drum seals can leak hot air out of the drum before it passes through the clothes. Overloading the drum is the simplest cause — too many items block airflow inside the drum. An appliance technician checks vent airflow at the exterior outlet, inspects the heating element or gas igniter, tests the thermal fuse and cycling thermostat, and examines drum seals. A vent-cleaning specialist snakes the full duct run and clears any blockage.