I just moved into my first home, and the bathroom fan is 100% ineffective. I can hear the motor run when I turn it on, and I remember going into the attic with the home inspector and tracing a flexible duct from the fan fixture out to a port on the side of the house. The fan was installed when the previous owners renovated the bathroom three years ago, so it's unlikely it's worn out from age.
But when I turn it on, it has absolutely no effect on the moisture in the bathroom. Water collects on the ceiling and fogs up the mirror and window. The only way to dry the bathroom out after the shower has been used is to open the window or open the hall door – both of which are very slow.
If I hold up a piece of tissue to the fan fixture, it doesn't blow around at all.
What can I do to fix this? Do I simply need a new fan fixture?