I also have the same problem as Damon.. 2007 Impreza wagon first the blower would only work on the 4th position and then the fan started making horrible noises.
I've never done DIY repair and as its getting warmer I decide I should get it fixed before I need the AC, so I call up the dealer, and have them check it out. They lead me to believe its just 1 part, even though I am emphatic about there being an issue with the fan AND the switch. The switch part came in today and I get a call that they have to replace the fan as well.
Sounds like its going to be ~400 for them to replace both the fan and the resistor, can't even seem to find the fan for sale online if I wanted it