Outdoor dryer vent flap stuck closed

The outdoor hood is the last door on the exhaust path. If that flap stays shut, warm damp air backs up into the hose and the dryer. Clothes need longer cycles, the laundry room feels humid, and lint builds up faster behind the machine.

Unplug the dryer before you disconnect any indoor duct. For a gas dryer, if you smell gas, stop and call your gas utility or a qualified technician.

What a healthy flap looks like

With a load running (or an empty timed cycle), stand outside at the hood:

The flap should lift open and stay open while air flows.
You should feel a steady stream of warm, moist air — not a weak puff.
When the dryer stops, the flap should fall closed so pests and cold air stay out.

If the flap never moves, or opens only a crack, treat the hood as the first place to clean.

Clear lint and debris at the hood

Turn the dryer off so you are not working in a blast of air and lint.
From outside, pull out loose lint with your fingers or a soft brush. A vacuum hose helps on a screen or grille if your cap has one.
Check that the flap hinge is free — dried lint, paint, or a bent pin can glue it shut.
Remove twigs, leaves, or nesting material. Wipe the flap so it swings freely by hand.

Do not run the dryer with the outdoor hood removed “for more airflow.” That dumps lint onto the siding and can invite pests into the duct.

Weak air after the flap moves

If the flap opens easily by hand but only a faint puff comes out during a cycle, the clog is likely farther in. Work through the indoor side of the two-cycle vent checklist — lint screen, hose shape, and whether you can see both ends of the run.

After cleaning, run a short empty cycle and watch the flap again from outside. Lint in a dryer vent is a fire risk; keeping the outdoor flap free is ordinary maintenance.

Outdoor dryer vent flap stuck closed

What a healthy flap looks like

Clear lint and debris at the hood

Weak air after the flap moves

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