I am getting a odor/fumes coming from the air vent. It only happen when my car comes to a stop and the fan kicks on. Since the fan kicks on at almost every stop, this happens often. I can actually see a fog of a sort coming from the vents as well. I have noticed there is a small coolant leak as well. But the leak is located by the coolant refill box and i dont think this is causing the smell. Can someone please give me some advise of fixing.