2001 BMW X5 AIr conditioner acting up

My symptoms are:
1. Blower is inconsistent---sometimes blowing hard, sometimes not
2. Air Tempture is not that cold
3. Air seems to be more cool out of driver side vent than others
4. When air is ON, seems to be making alot of air blowing (when blowing hard), but not a huge air flow---like trying to get out of other vents?
5. There is a churp in a vent somewhere in the dash.
All symptoms seem much worse when driving on freeway, hotter conditions.
I am interested in what to expect for repair, and would like to be somewhat educated before taking it in.