a/c retrofit; drain hole location?

Hi all,
I retrofit an a/c system into my '90 XJ last year; I grabbed the system from a '89, so it went in pretty well. I was mucking with the wiring for the door locks over the weekend and pulled back the carpeting to trace it. The carpet padding on the passenger side was soaked.
I thought about it, and looked over the parts diagram; I think the problem is that I never routed the drain properly.
I don't recall if I switched the actual box or not (I *think* I did). I just remember connecting the tube from the box to the blower fan and thinking that was a weird way to route a drain. I don't recall seeing any other holes in the box.....
At this point, I really would rather not switch out the box twice (once by grabbing one from the scrapyard; twice by putting it into mine). Can I visually id if I have the correct box (i.e. where should I see/find the drain hole)? If I don't have correct box, can I simply drill a hole in the correct location? Or is there some internal shape difference/checkvalve that I need to worry about? Can I retrofit the current box to work correctly?
Anything that will save me hours of work greatly appreciated! :laugh:

Thanks!

This is the box from my 89. The hole under the blower mount is a vent for the electric motor. Then the AC drain is the smaller one to the right with a gasket. The small piece of hose goes on the end of it inside the engine compartment. The AC drain could have a bad gasket or the small piece of hose is plugged or missing.

Thanks Mesh! That helps a lot. I appreaciate it.