My a/c button wont come on on 2005 Chevrolet Malibu

my check engine light my ABS warninglight came on along with my reduced power engine message came on at the same time. . so I take it to a mechanic shop and end up replacing the throttle body the fuse box andthe brake pedal .. sensor.. after almost $900 I finally get my car back after 2 weeks later and my air conditioner is not working at all and was working perfectly fine before I got there what could it be?!

1 answer
scan codes and post so we can adv. take back for poss warranty issues and explan concerns but be nice and see what they will do for you first