Most people clean the lint screen and figure the job is done. It isn't. The lint screen catches maybe 60 percent of what comes off your clothes. The rest packs into the duct that runs from the back of the dryer to the wall, and from there out of the house. That hidden buildup is why the U.S. Fire Administration ties clothes dryers to roughly 2,900 home fires a year, with the single biggest cause listed as failure to clean. June is the right month to deal with it, before the summer heat has your dryer working against a warm, humid garage or laundry room.
The warning signs you already have a problem
You don't need a meter to know your vent is clogging. The dryer tells you. Clothes that used to dry in one cycle now need two. The machine and the laundry are hot to the touch at the end of a load. There's a musty smell, or the top of the dryer feels warmer than it should. Outside, the vent flap barely opens when the dryer runs, or you can't feel much air pushing out of it. Any one of those means lint is choking the airflow, and a dryer that can't exhaust heat is a dryer running far hotter than its designers intended.
The 20-minute cleanout, start to finish
Unplug the dryer first. If it's gas, shut off the gas valve behind it too. Pull it a couple of feet from the wall — most of the slack in the cord and duct is there for exactly this. Loosen the clamp on the flexible duct where it meets the dryer, then where it meets the wall. If you still have the white plastic or thin foil accordion duct, this is the moment to replace it with rigid or semi-rigid metal; the ridged plastic kind traps lint and is flagged in the IRC for a reason. A 4-inch semi-rigid metal kit at Home Depot or Lowe's runs about $15 to $25.
Now clear the line. A dryer vent brush kit — a long flexible rod with a round brush on the end, around $20 — pushes through the duct and out the exterior vent. Run it from both ends. You'll be surprised, and a little disgusted, by what comes out. Vacuum the lint trap housing while you're in there; a crevice tool reaches most of it, and a $30 shop vac does the rest. Check the exterior flap last. If it's painted shut, cracked, or jammed with a bird's nest — that happens more than you'd think — replace the wall cap. Reconnect both clamps snugly, push the dryer back leaving a few inches of breathing room so the metal duct isn't crushed flat, and run a 10-minute cycle on heat to confirm strong airflow at the outside vent.
Why this shows up on your power bill
A blocked vent doesn't just risk a fire. It forces the dryer to run longer and hotter to do the same work, and that's energy you're paying for. Department of Energy figures put a typical electric dryer at roughly $100 to $130 a year to run; a badly clogged vent can add 20 to 30 percent on top of that without you noticing, because the increase creeps in load by load. In a summer where you're already fighting your AC, a dryer dumping extra heat into the house from longer cycles makes the cooling bill worse too. Clearing the line is one of the few maintenance jobs that pays you back the same month.
What to leave to a pro
If your laundry is on a second floor or in a finished basement with a long, twisting duct run — anything past about 25 feet, or with several elbows — the brush kit won't reach the middle, and you can pack lint tighter instead of clearing it. That's the case for a professional cleaning, which runs about $100 to $170 in most US metros and includes a camera check. Same goes if you smell gas at any point near a gas dryer: stop, leave it, and call the gas company. For everyone else with a standard wall vent, this is a Saturday-morning job that costs less than a single restaurant dinner and takes one risk off the table for good.
Put it on the calendar for the same week every June. Lint never stops, and a dryer is the one appliance in the house that quietly stockpiles its own kindling.