ITAC provides students, faculty and staff the Adobe Creative Cloud: Service - Adobe Creative Cloud
The program within that group of services that can help with converting pdfs is Adobe Express. If you upload an image-only pdf into it, the program will convert it to OCR automatically.
Additionally, you can choose a variety of Add Ons from the left hand frame (search Accessibility after selecting Add Ons). Many of these Add Ons are accessibility checkers or other tools for making your pdf accessible.
Disclaimer: We haven't tested the final products out with a screen reader yet. Let us know your experience.