Welcome to the forum!
What I'd suggest is that you start with the DCCV circuit. If you find the DCCV does not appear to be working probably, replace it, then see how the system performs. If all seems well, you probably can ignore the 12 65 code.
If you feel comfortable pulling the DATC from the dash, you could check for the cold air bypass wiring. I would consider "blend door" as synonomous to "cold air bypass."
-Rod