Why should there be water coming into both sides of the interior? on 2007 Buick Terraza

The ac drain hose has been checked by 2 different professionals and it is clear. The water intrusion begins about 20 - 30 minutes after the ac is turned on.

Asked by for the 2007 Buick Terraza
When the engine is running with the a/c on do you have water running out the HVAC box?
Yes, and no. It varies, depending on how the ac has been running.
It doesn't matter how the a/c is running. When the a/c is on you should and must have water running out of the evaporator drain. Meaning water dripping outside on the ground. If not you have a restricted evap drain.