Yep..............as 287cc stated, it can be a sign that the fan motor is going.
Don't go to the stealership for this. E-bay has them far cheaper and they are excellent quality.
However if this is a pre 06 vehicle, the fan shroud isn't a modified version. That, also along with a modified fan motor and also a wiring pigtail.
What can happen in the early designs of these fan shrouds is, when it's cold enough for ice, if a pool of water has formed at the bottom of the fan shroud this water freezes and stops the fan blade from turning as the blades are frozen fast in the ice.
This blows the fan fuse and can also destroy the fan motor.
What I did, was drill a few holes into the bottom of the fan shroud to let the water drain away.
Check to see if this is what's happening to your ac fan assy.
Hope this helps?