A/C is always on

Knob broke from behind?
AC Heat knob.jpg
 
Why is my A/C always no no matter where my selector know is?
Could this be the cause of parasitic battery drain?

If whatever is wrong is keeping the A/C clutch engaged all the time, yes, it could. With your TJ off, check for 12V at the A/C clutch. If you have it, you'll then need to diagnose why.