Do I have to take it to the dealer to get the AC recharged or can I use a can from an auto parts store to do it myself? I ask because my AC works, it's just not as cold as it should be and takes a while to get even a little cold.

Any idea on the ballpark cost if I have to take it to the dealer? I don't think it's malfunctioning. No noises, overheating, or otherwise.  

I have an '01 TTQC 225hp.  I recently thought that the AC wasn't cooling enough.  I happened to be at Wal-mart and was in the auto section.  Looked at the AC refridgerant offerings.  Actually bought a large can (R134?) that has the pressure gauge in line (white can, with blue hose & gauge).  Once you identify the low-pressure side... this is critical, you can easily attach the hose, much like a tire pressure valve, and check your system pressure.  The low pressure valve is near the radiator: if you are facing the car with the hood up, it is on the left hand side, between the after-run coolant pump and the radiator as I recall.  A Bentley manual should show you where the low pressure valve is.  When I checked mine, the pressure was a bit low (according to the directions given with the R134 can).  Following the directions on the can, it took the whole large can and only bumped the pressure up a bit.  I perhaps could use another small can.  A plus I wasn't expecting was that my AC always made a barely perceptible pulsating, ringing sound when engaged.  Once I added the r134 (which I also think contained oil for the system, as well as leak preventer), that sound was gone.  So either the extra R134 made it go away, or the oil (?) in the R134 lubricated the system.  It was all very simple (following the directions).

Thanks Patrick! I'll give that a try. I'm a bit relieved to find that I don't have to take it to the dealer.

Does it matter what brand?  I will go to Walmart and see if I can get a bottle of that stuff.  My AC is working okay but I think it can do better or blow a bit cooler air.  My brother has a Passat and his AC freezes me out.  Mine not so much     Also is the low pressure connector easily visible?  Is it somewhere on top where you can easily get to?  I will check under the hood tonight and see if I can find it. 

The low-pressure port is obvious when you pop the hood. It's the light-blue cap, front of the engine compartment toward the passenger side. 134A systems, unlike R-12s, have different sized ports for the low- and high-pressure ports so they can't be mis-connected without really working at it.