Hello! That's a great video! Quick question for you - do you happen to know the part number for the mode door actuator for a 2012 Odyssey?

 

If your rear AC is not blowing air out of the top or bottom vents, you need to change the blend motor actuator. First verify if the rear blower motor and resistor are good.

OMG, you used an impact to bust the nut off, that ain't much of DIY.... JK

I had a similar problem with my front driver side few years ago. I disassembled the blend motor, clean the horseshoe resistive track and the contacting wipers extremely carefully, applied electronics grade lubricant grease on it and it fixed my problem. It's still going well.