Yes, the factory charger is liquid cooled. The battery modules are not. My 6.7kW upgrade charger is air-cooled for simplicity, but could be hooked into the existing liquid cooling system. (It's more efficient then the existing one, so it wasn't worth the hassle)
Now adding cooling for the pack is a whole different problem! Most cars have used the A/C compressor, because using a standard liquid to radiator system cannot cool the pack below ambient. So a liquid cooling system without a refrigerant cycle of some sort would be of little gain to a system in Arizona. It would also have to be isolated from the the charger's system, otherwise it would actually ADD heat!
There is almost no noticeable difference in pack temperature when I charge at 6.7 vs 3.3, but I can adjust the charge rate through
LEAFSCAN™ if I need to reduce it for some reason, such as limited current available.
-Phil