Fan won't work on low setting

I have a 2001 Olds Alero. The fan has 5 speeds (six if you count the off position) and it will not run on the lowest speed. I replaced the fan switch, but still won't work on lowest speed setting. Anyone have any ideas?

Replace the blower resistor. It should be located under the dash next to the blower fan. The speeds will slowly go out until all you have left is high. The resistor will cost about $40 at a dealer.