water on pass floor

I have a 96 olds bravada and my prob is when it rains my air box fills up with water. It drips from behind the dash and if I push the flap for the max air under the dash the water gushes out its destroying my carpet my? Is where is the drain and how would i clean it if it’s clogged from the inside. I think it’s full of pine needles I use to park it under a pine tree thanks

The drain should be in the engine compartment.

i cant seem to find it i am ready to drill a holl in the bottem of the box

In a related post, Old Master sez...
"The evaporator drain is very close to the exhaust pipe and if the heater core is leaking, coolant could drip on the exhaust pipe very easily, and give off that "sweet" smell."