Searchable text from pdf imported into InDesign

I am working on a very large technical manual in InDesign. For the vast majority of the pages, I import pdfs with technical drawings and specifications my R&D department creates in AutoCAD. I need the text specifications to be searchable in the final document, but can't figure out how to do this.

The text is searchable when I open the pdfs independently, but once they are placed in InDesign, search function is lost. I've tried altering the Import Options, but still no luck.