1993 cutlass ciera heater problem

When I turn my heater on to 1 everything is fine a heat lightly shoots out the vents. When I put it to position 2 ot higher it makes a terrible noise and doesn't work. I want to change the motor that shoots the heat out but before doing so I want to make sure I know what I'm doing.
Where exactly is it located and would anyone have any helpful advice (or pictures or websites that show how to replace this).
Thanks in advance for any help.

Your best bet would probably be to get a Chilton's or Haynes book for your car. Just go to your local parts store to order one.They go for about 15$(cdn)