What is this hole for?

[69hugger]

Can anyone tell me if this hole leads to the interior & it's purpose? I am referring to the 3 x 6 triangular hole in the cowl facing sideways in the center of the pic.



I reach into it & I think I can feel the Vintage Air box, but can't tell for sure. If it is the fresh air intake for the factory HVAC system, do I need it with a V/A unit?
I ask because this leads back to an issue with my car where on extended driving, (over an hour) on hot, humid days, I get condensation dripping from under the dash, coming from the A/C ducts.
If this is a massive air leak coming in under the dash, seems to me blocking this hole may be the answer.
Do I need fresh air coming into the car, or is recirculating & cooling what is in there & cracking the windows sufficient?
What about the similar hole on the drivers side? That seems to lead nowhere, but I can't tell for sure.

As always, thanks for the help!!