Have you moved the vent selector around to see if the driver's vents close off properly in other settings like the DEF?
I'd have to do some research to be sure, but the blend door is behind the console if I'm thinking correctly, and if the problem was cutting off the outside air- then you'd have hot air on all vents.
If you have trouble getting the air to come out of different vent selections, then start tracing down the AC control vacuum under the hood that provides power for the blend door. If that vacuum line is damaged, then the vent selection won't work, or if it's a minor leak then it won't work instantly.
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Originally Posted by the user formerly known as ZX3_Chick
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