* Brewtoo, what does "diagnostic mode" mean? Can you initiate a blink-code test (of the ACC) from the recirc switch? If you can, how do you do it? And how can I turn it on at will? If it only starts blinking when the scan tool is connected to the data port, what purpose does it serve?
* I should get a single blink followed by a longer pause since the scan tool found no codes in the ACC, tested just moments before the blinking. And the HVAC appears to be working ok.