a/c problems 95' deville

This has been going on for while but my a/c blower goes in and out I thought it was the blower itself but I changed that and it fixed for a while and now it's back to the same ol' thing but now when I'm driving it blows and when I stop it stops any insight as to what this might be because I'm thinking it's the programmer and cadillac wants $700 for that so before I buy one I would lilke to try and confirm it