Case sensitive search in Access query

[Paleo]

I need a way to tell MS Access to look for a litteral charater. I have a single character field that allows both "A" and "a" as valid characters. They are seperate entities and I need to call "A" sometimes and not get "a" mixed in.
Thanks for the help, I am really struggling with this one. Perhaps it is as easy as an option I do not have selected, however...I can't seem to find any information on either.
Thanks again.
Doug