The AFG SMT-3.0 features a 10-speed ECM motor that automatically changes speed based on temperature and humidity conditions within the attic.
Sometimes this automatic speed change can cause a slight, tinny vibration sound on certain gable vents when the fan is switching down to the lower speed ranges.
To prevent this, please follow the steps below.
1. Purchase general silicon caulking from any hardware store.
2. Caulk over the steel mesh that touches the horizontal slats of the gable vent.