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...
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.