I had a issue where my blower only worked on the highest setting regardless of the position of the switch. I looked into the schematics and noticed the blower resistor pack wasn't used for the highest setting if memory serves, (it's been a while) It would be worth looking into, if you don't notice a change in sound or flow when rotating the blower speed switch.
http://www.irv2.com/forums/f115/blow...an-150607.html
Good luck, something is up because mine works pretty darn good.........