New HVAC Problem - Not Recognized

[jquattro]

Hi,

I just bought a '02 A4 1.8T Quattro, manual, for my sons first car and have a question. The previous owner replaced the HVAC unit with a newer unit that has the "Off" button. It seems to work just fine in the car, but my VAD software will not communicate with it, so I cannot program any of the functions that are controlled through this unit, nor can I see any fault codes. Any help would be greatly appreciated.

[Spike00513]

IDK much about B6 HVAC, other than supposedly you shouldn't put a B7 box behind the faceplate.
I accidentally did that. And now electronic button rear defrost doesn't work. Good thing I kept my B6 box, for me to swap the clean faceplate onto. It's held on with torx screws.
The idea was to get rid of the old scratched unit and just throw in a good one from a B7 which looks the same. But as I pointed out; no rear defrost that way. So I'm not done yet.
Both of them had "Off" button though.

[imnuts]

Everything is plugged in behind the unit right? Any pinched or damaged wires?

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