I am looking at the schematic:

Low goes through all 3 resistors in the pack

1 goes through 2 resistors

2 (missing speed) goes through 1 resistor

High switch goes past the resistors, which is why it works on high. It looks like if you unplugged the whole switch you have low speed only, and if you unplugged the resistor it would run on high as you found. You might have a bad connection on the terminal for speed 2 in the resistor (I did on my Dodge a while ago, rust) or a bad switch. Take out the resistor pack, and have a look, easier than removing the switch. This FAQ and procedures may help.

http://www.contour.org/FAQ/FAQ.php?s=probs&displayid=23

I tried linking to diagrams below, but you would need to subscribe to alldatadiy.com.

Schematic! use 3rd picture

Remove blower resistor alldata

Remove climate control switch panel alldata

Maybe I could e-mail them if you need them.