OT: Help me help a friend. AC related.

Ok a buddy of mine drives a newer model Dodge Stratus (2001ish). The AC on the car has settings 1, 2, 3, and 4. Just recently it stoppped working, except pn the setting 4. What should i be looking to replace? It performs the same as the 4th setting always has, but the only problem is settings 1-3 dont work. Ideas, advice or just pointing me in the right direction would be greatly appreciated.
 
90mustangGT said:
blower motor resistor.
+1.

See AutoZone for wiring diagrams. The resistor assembly typically is mounted in one of the air ducts since it gets hot and the moving air helps to cool it. It will have 3 or 4 wires connected to it. When it is removed, you will see 2 or 3 small coils of wire with no insulation on them.