When dryer vents are constructed of incorrect materials, such as vinyl or "metallic" flex hose, lint and moisture can accumulate to shut off the airflow to the dryer. This is a safety issue as well as an energy thief!

This video shows what this lint-moisture mixture looks like...and how to avoid it.

Dryer Vent Wizard of Middle Tennessee, Dryer Vent Cleaning, Clarksville, TN