Re: Help please! Strange vent problem...99 Ranger
Sounds like a loose blend door. Not an easy fix even for a DIY person as it will require taking apart the majority of the dash to get to the HVAC box that houses the blend door.
When you open your window this takes away any back pressure to the air coming in through the vent and allowing more of a breeze to pass through the cabin. Obviously the faster you drive the more air will pass through with the window open. This is one of the many reasons airliners use pressurized cabins; besides having enough O2 for one to breath above 10,000ft ASL.
'00 Durango R/T 360ci 290hp (modded); 138,500m
'06 Pontiac G6 GT 3.5L 220hp; 44,000m
'12 Chrysler 200 Limited 3.6L 283hp; 13,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!