Aussie VC 67 Dodge ute

I'm changing the lower A pillars so the blockage from factory will be gone. The small amount of fresh air that will come in from the wiper arm holes will then pass up the A pillars and into the cabin. Effectively becoming flow through ventilation. Vintage air is also fitted and as it doesn't require outside air, and I needed the space for electrics/electronics the space for the vents is used for that!
Blockage? I'm not familiar with that. Enlighten me please?