A dryer that runs a full cycle and leaves clothes damp is the most common call we get. It is also the most misdiagnosed, because the obvious conclusion is that the dryer stopped making heat, and most of the time that is not what happened.

Work through these in order. The first few cost nothing and solve a real share of cases.

Start with the load itself

Two loading mistakes produce damp clothes on a perfectly healthy dryer.

Too full. Air has to move through the laundry, not around it. A drum packed past about three-quarters of capacity does not allow that, and this is the single most common cause on the list.

Too empty, on a sensor dryer. This one surprises people. Automatic cycles end when moisture sensor bars stop detecting wet fabric. A very small load may not brush against those bars often enough, so the dryer decides it is finished early. Adding a few more items fixes it.

Mixed fabric weights cause the same thing. Towels and t-shirts together means the cycle ends when the light items are dry and the heavy ones are still wet.

Clean the lint screen properly

Pulling the visible lint off is not enough if you use dryer sheets. Fabric softener leaves a film that blocks airflow while the screen still looks perfectly clear.

Test it. Run water over the screen — if the water beads and sits on top instead of passing straight through, it is filmed over. Scrub both sides with hot water, a little liquid detergent and a nylon brush, then rinse and dry it.

Then look underneath. Lint gets past the screen and collects in the housing it sits in, and a clean screen in a packed housing still restricts air.

Check the vent, because this is usually the answer

A dryer works by moving heated air through the clothes and pushing the moisture outside. If the air cannot get out, the moisture stays in the drum. The dryer heats perfectly well and the clothes still come out wet.

The test costs nothing. Run the dryer and go look at the exterior vent hood. You should feel strong steady air and see the damper flap pushed open. Weak air, or a flap that barely moves, means a restriction somewhere in the run.

While you are behind the dryer, look at the transition duct. Crushed flat against the wall, kinked, or made of ribbed foil — any of those alone can be the problem.

Some dryers tell you outright. LG models with airflow sensing display a code beginning with d, and the number after it is the percentage of blockage measured. Samsung lists a clogged lint screen or vent as the most common cause of its heating and temperature codes. See dryer error codes by brand.

Check the breaker if it tumbles but never heats

An electric dryer runs on 240 volts, delivered as two legs of 120. One leg powers the motor and controls. The other powers the heating element.

If one leg trips or fails, the drum turns, the timer counts down, the machine sounds completely normal — and no heat is ever produced. People replace heating elements over this.

Reset the double breaker fully, off then back on. If the dryer heats afterwards, that was it.

Try a timed cycle

If timed dry works fine and the automatic cycle does not, the moisture sensor is misreading. Fabric softener residue coats the sensor strips so they read dry when the clothes are not, and the machine shuts off early.

The strips are usually two metal bars just inside the drum opening. Wiping them with rubbing alcohol sometimes restores them.

When it is genuinely the dryer

If airflow at the hood is strong, the screen is clean, the load is right and timed dry still leaves clothes damp, the fault is in the machine.

A partially failed heating element. On electric dryers the element can fail in stages rather than all at once, so the dryer warms but never reaches temperature.

A tripped thermostat or thermal fuse. These are safety devices and they trip for a reason. That reason is nearly always overheating caused by restricted airflow, which is why replacing a blown thermal fuse without fixing the vent means replacing it again.

Gas supply problems. On a gas dryer a weak igniter or failing flame sensor produces short heat cycles or none at all.

A failing blower wheel. Less common, but a cracked or lint-packed blower moves less air even behind a clear duct.

Reading the symptom

• Clothes hot but damp → airflow, almost every time
• Clothes cool and damp → heating element, thermostat, or a lost breaker leg
• Timed dry works, auto does not → moisture sensor
• Cycle stops early and the dryer is hot → overheating on a restricted vent
• Got worse gradually over months → lint building in the duct
• Happened suddenly → a component failed, or a breaker tripped

If the vent is the restriction, cleaning it fixes the drying. If the dryer is at fault, it needs a diagnosis. We check both, because replacing a part on a machine with a blocked duct fixes nothing and the part fails again.