2 questions!

Both questions are in regard to my 1971 dart swinger 360 w/factory ac.

1) when I switch the panel to defrost it continues to blow out the vents. From what I can tell I don’t have a broken vacuum line and ideas on where to start chasing this rabbit hole?

2) how do I remove the vent box (see pic) from under the dash? I’m trying to get the radio out and it seems to be in my way.

thank you as always for the help!

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