Mine dosen't .Mine ticks as well.
I know how to fix the problem with the audible ticking...
...Turn up the stereo!
...or if you're in an S5, open the window and depress your right foot onto the pedal on the right until it will go no further!
Seriously though, I get my car on Wednesday and will check this out, and also ask my dealer. None of my previous Audis did this, nor my parent's 3, nor my brother's 2, so don't think it's that common if it's the climate control.