The a/c is either off or full blast... how much of a pain is it to change the selector switch yourself? And what website would I order the part from?

There was a couple AC problems known to the 2000. Are you saying the selector knob feels like it is pulling/pushing against something when you turn it, or does it feel weak when you turn back and forth, or does it feel normal but AC will only function wide open?

The knob switches between 1-4 fine, but the compressor and fan only come on on 4 (full blast). I ordered a resistor, I hope this is the fix, and I understand it's right behind the glove box? Hopefully a quick fix...

Send feedback when completed ?

That's typically the fix. When the resistor goes, you progressively lose fan speeds until only highest is left...and that's what you seem to have.

I did a write up with step by step pics on how to replace that if you need it...but its pretty straight forward.

Yep,5 minute fix, didn't even remove glove box!