Combine ACAD files without capturing...

I regularly combine hundreds of AutoCAD files, in this case, electrical drawings, into a single PDF file for printing and distribution to customers with their machines. The problem I'm having is that when I convert these, Acrobat ALWAYS captures the text on the drawings as both text and an image, creating a wierd, shadowed overlay that makes them unreadable. Going through and removing the text from the document is a pain, because adobe doesn't recognize some of the fonts that appear on the drawings, so it won't allow me to simply delete the text. I have to go around and highlight all the text on each page, while avoiding that one little string, to get the text removed.

Converting these one at a time isn't an option, since that would eat up 8 hours of my day every day right there. Is there a way I am not aware of that I can Combine files into a single PDF without capturing the text? I only need them as an image. They should never me altered.