About the only way you're going to find any leaks is to get up there and look for them then seal them with duct tape.
I have some doubts that there is a leak though. You may just be smelling the normal damp musty smell that comes from air conditioning units when they first start up. You also may need to clean the filters or the drain on the unit, they collect lots of dust and grime and will smell a lot like an attic when dirty.
In all my years of doing repairs I have only once seen a split duct in a house and that was because a kid hit it with a pool cue. It's not a very common occurrence. |
