Standard mildew smell. You can try so rid the smell with a few shot of Lysol. Open the hood, look on the passenger side for intake grates, and fire a few shots with the fan on high, with the setting to the floor.
To prevent this from happening again, when you have the a/c on, turn it off, but leave the fan on high, a few blocks from home to allow the hot air to blow away any dampness that gathered on the sides of the ducts when the a/c was running. I have been doing this in all my vehicles and have never had the smell, at least, not from the vents!!