Is there a "drain" for condensation from the air conditioner in a 1999 740i? If so, how can I find it and insure that it's not blocked? Thanks!!

http://realoem.com/bmw/diagrams/r/o/227.png

10, 11 & 12 are condensation water outlet hoses.

It's kind of hard to tell where these things are on your car by this illustration, but here are two links that will help:
http://www.bimmerboard.com/forums/posts/244196
http://www.bimmerboard.com/forums/posts/57582

Just out of curiosity, why are you worried about them?

Is there a "drain" for condensation from the air conditioner in a 1999 740i? If so, how can I find it and insure that it's not blocked? Thanks!!

The easiest way to tell is look under your car after using the air conditioner, you'll see water dripping onto the ground.

I'm getting that nasty, moldy air conditioner smell whenever I switch it on, and I'm concerned that the condensate drains are blocked with the same nasty, moldy stuff that causing the odor. I've seen some recommendations to shoot compressed air into the drain to dislodge whatever is causing the blockage. Not as much fun as tearing the dash apart, but, followed with some disinfectant into the intakes, the process might solve the problem.

I'm not at all certain that the drain is blocked, but I'll start looking for the dripping water next time I'm out. Thanks!! I'm embarassed not to have thought of that myself.

I get that same, moldy smell sometimes, but only when the air conditioner is off and I'm pulling in exterior air instead of recirculated air.

And maybe some guys might recommend replacing the recirculation filters and the microfilters, but those aren't causing the moldy smell (however, if you haven't changed those filters recently, you really should. http://www.autohausaz.com/search/product.aspx?sid=lkgupzupfxy3vyvaf1pgbyab&makeid=800003@BMW&modelid=1303254@740I&year=1998&cid=24@AC%20%26%20Heat%20-%20Climate%20Control&gid=6832@Cabin%20Air/Pollen%20Filter (http://www.autohausaz.com/search/product.aspx?sid=lkgupzupfxy3vyvaf1pgbyab&makeid=800003@BMW&modelid=1303254@740I&year=1998&cid=24@AC%20%26%20Heat%20-%20Climate%20Control&gid=6832@Cabin%20Air/Pollen%20Filter%29)).

Anyway, the image and links I gave you before deal with parts that are no where near the air ducts, so those won't really help.

I bet the mold smell is simply a result of water mold build-up over a long period of time, and not a plugged up drain.

What you've got to do is take out all of the air ducts, and wash 'em.

I'm getting that nasty, moldy air conditioner smell whenever I switch it on, and I'm concerned that the condensate drains are blocked with the same nasty, moldy stuff that causing the odor.

Here's whats worked for me:
http://www.bimmerboard.com/forums/posts/267107

It's a common problem in our e38s.

Parts stores sell a special spray just for that smell ,I have seen the aluminum on the evap corrode cause that smell

Oh and the drains are hard to find they are at the top of the transmission tunnel it almost drips on the trans