The dryer also has a couple of safety features that help to prevent overheating. There are two temperature shut-off switches. When these switches reach certain preset temperatures, they break contact, which shuts the dryer off. The first switch is located near the lint screen.
The picture above shows the front of the dryer, with the front panel partially removed. The first temperature sensor is on the right. And to the left, you can see a set of six holes in the outer edge of the tumbler. These holes are only there to blow hot air on the sensor every time they go by. If the temperature in the tumbler gets too hot, this sensor cuts the power, shutting the dryer off.
But what happens if the belt breaks and the holes don't happen to be in front of the temperature sensor? Or if the fan gets clogged and no air is coming out of the tumbler? This is where the second temperature switch comes in.
The second sensor is located close to the heating elements. If airflow is shut off for any reason, the air near this sensor will quickly heat up to the temperature that triggers this sensor, and the sensor will shut off power.