We get called out for "the dryer isn't working right" more than almost any other complaint, and a genuine mechanical fault turns out to be the cause less than half the time. Far more often, the vent run — the ducting that carries hot, humid air from the dryer to the outside — is restricted, and the dryer is doing exactly what it's supposed to against too much resistance.
Clothes take two or more cycles to dry
This is the single most common sign. A dryer venting properly should dry a normal load in one cycle. If you're routinely running a second or third cycle for the same load, restricted airflow is the first thing worth checking, well before assuming the heating element has failed.
The outside of the dryer feels unusually hot
Heat that should be venting outside is instead building up around the cabinet because it has nowhere to go. This is also the early stage of a genuine fire risk, not just an inconvenience.
You can smell something burning, faintly
Lint accumulating on the heating element or the exhaust duct itself starts to smell as it heats repeatedly. This is worth acting on immediately rather than running another load and hoping it clears.
The laundry room feels more humid than it should
If moist air is escaping back into the room instead of venting outside, that's a direct sign the exhaust path is blocked somewhere along its length.
It's been over a year, or the run has bends and length
Even without obvious symptoms, a vent that terminates through the roof, has multiple bends, or runs longer than about twenty-five feet collects lint faster than a short, straight wall vent. Annual cleaning is the standard recommendation, and longer or more complex runs sometimes need it more often.
Why this matters beyond drying time: according to fire safety data tracked over many years, dryer lint buildup remains one of the leading causes of home appliance fires. A vent that takes two cycles to dry a load isn't just an efficiency problem.
What a proper cleaning involves
A thorough job means clearing the full run from the dryer connection to the exterior termination point, not just the flexible section behind the machine. If you've had the flexible duct cleaned before but never the rigid run through the wall or roof, that's often where the real blockage sits. If the dryer itself is also making noise or running cold even after a clean vent, our dryer repair page covers the more likely mechanical causes.