I have a very loud hissing sound coming out of around the ac/heater dials. If this is a vacuum leak, is this something a "regular Joe" can fix, or do I need to take it in? Get's really loud when defrost is on, but it is constant.

 

It is most likely a vacuum leak, but they can be fixed by a novice if you have the time and patience. The vent controller is run off of vacuum from the engine and can be a pain to find sometimes, but look under the dash, behind glovebox and hopefully you can remedy the problem.