A/C not working need some help

[the newguy]

i was trying to run a wire through the grommet under the dash for the fog my lights . after 4 hrs. i gave up i put the bumper back.then when i turned the car on the A/c didn't come on. it's not a fuse because all the lights are on the cd play and a/c display. i think i may have loosen a wire some where my buddy is going to try to help me on friday can anyone give me an idea to were i should start or were the the a/c connection is! i would gladly appreciate it !