Stop in for a cup of coffee

Morning everyone

general car question for you:

My 2008 Eclipse's HVAC system has a slight "scratching" sound to it when I turn it on. The best way to describe it is if you took a portable fan and ran it across a piece of paper. Like a "Thwapping" sound, literally sounds like something is running against it, but it happened over night, so I'm not sure.

I'm thinking either a resistor (common eclipse problem) or clogged blower motor, any ideas on this?