The reason the cowl is open is so that you can use the heater for outside air. If the cowl vents had been CABLE controlled like mustangs and B bodies they would have been way more useful. Or if the heater had been configured to make use of cool outside air IE if only Ma had put WATER VALVES on all heaters instead of only AC
and just so ya know, those "antique" cowl vents leaked too!!!! My Dad had several of the 50's era GMC/Chev pickups and at least one of them leaked and dripped rain water. I was young then so don't remember. "It might have been" a rust problem.
What would have been nice is if the cowl was removable so you could clean the damn things out!!!
