Airflow restricted
The dryer measured the air not moving through the drum the way it should — a vent that is long, kinked, crushed or full of lint, or a lint screen caked with softener film.
- The lint screen is clean and water runs straight through it; a screen that holds water is scrubbed with dish soap and a brush.
- Pull the dryer out and look at the duct behind it: not crushed flat against the wall, not a sagging foil hose full of lint, no more than two bends between the dryer and the wall.
- Outside, the vent hood opens when the dryer runs and the flap is not stuck shut with lint, paint or a bird's nest; air should push out hard enough to feel at arm's length.
- The run is short enough: about 35 feet of rigid metal duct at most, with each 90° elbow counting as 5 feet and each 45° as 2.5 — a long run through the attic is over before the lint even starts.
- The test that settles it: with the dryer pulled out, take the duct off the back and run Air Fluff for a minute. Strong air at the back and the warning gone means the duct is the problem, not the dryer.
Clean the duct end to end (a dryer-vent brush kit from the hardware store does it from the outside), straighten or shorten the run, replace foil hose with rigid or semi-rigid metal, and clear the hood. A Check Vent that stays on with the duct off the back and the screen clean is the blower wheel or the vent sensor — a part, and on a machine under warranty a warranty call.
Check Vent that stays lit with the duct disconnected is a service call. A dryer that runs hot with no airflow is what its thermal fuses are there to stop, so leave it off until it is looked at.
