The ducting system may be too long, clogged, or kinked.
Check the diameter of the ducting system (if possible between 5" and 6" (125 and 150 mm) in diameter.
Check whether the ducting system can be shortened. Consult an expert if you have any questions.
Check if anything has blocked or obstructed the ducting system.
Check whether the ducting system is kinked at any point.
