I think you need to take the whole black trim piece out. The one that goes around your vents and instrument panel. That will open things up for you to get behind the control unit. All the screw locations are in your Haynes or Helm manual. A couple of locations I can remember: behind the vents, above and behind the ashtray, on the upper lip of the instrument cluster area... hmmmm, I know there's a bunch more. Just look around for them. It's not hard to do. Good luck.