If your dryer needs two runs to finish a normal load, the machine is usually fine — the air leaving it is not.
A dryer does not really dry clothes with heat alone; it dries them by moving hot air through the drum and carrying the moisture outside. When that airflow is restricted, the heat stays in but the moisture does not leave, and cycle times double.
Symptoms of restricted airflow
- Clothes are hot but still damp at the end of a cycle.
- The laundry room feels humid or smells warm while the dryer runs.
- The outside vent flap barely moves when the dryer is on.
- Lint appears around the door seal or behind the machine.
- The dryer shuts off early on a thermal trip and restarts once it cools.
Where the restriction usually is
In order: the lint screen (clean it every load — fabric softener sheets leave a film that needs a wash under hot water every few months), the flexible transition hose behind the machine, the rigid duct running through the wall, and the exterior hood, where lint mats up behind the flap or a bird decides to nest.
“Every extra metre of duct and every 90-degree elbow costs you airflow. Short and straight dries faster and safer.”
The safety side of it
Restricted dryer venting is a recognised fire risk. Lint is highly combustible, and a dryer that repeatedly overheats will eventually trip its thermal fuse — the fuse is a safety device doing its job, and simply replacing it without fixing the airflow is how fires start.
If the vent is clear
Then look at the heating element or gas valve coils, the cycling thermostat, the thermal fuse and the moisture sensor bars inside the drum. Those are the parts we test on a service call, and most are same-visit repairs.