I have a 2006 GS300. I changed the oil myself last weekend, and as soon as I got back on the road, I started noticing a cold mist from the center AC vents when my AC is set below 74. Has anyone had this happen? It's been a week now, and I'm almost ready to take it to the dealership. The AC blows fine, it's more annoying than anything else.

 

It happens because of the humidity level in your area. That mist is basically water vapor or call it fog if you will. The inside of your GS has reached it's dew point so you see the mist at that certain temp. I can see you're from Florida where the relative humidity is fairly high at this time of year.

BTW, are you using FRESH or RECIRC mode for your vents? RECIRC is best to keep from drawing the moist/humid air from outside.