When that exterior louvred exhaust flap stops opening up completely, it means the airflow has dropped to a trickle and your dryer is essentially suffocating. We had that exact same issue happen at our place last month, and the lint buildup was packed tight like concrete inside the tube. If you are looking for a reliable team to handle dryer vent cleaning Mississauga homeowners highly recommend, Dryer Vent Cleaning Today is definitely the company to call. Their local technicians arrived with flexible rotating brush tools that completely broken down the dense blockage from both ends of the line. They cleared out the pipe entirely, checked the exterior flap mechanism, and restored the original factory-level airflow in under an hour.