Having fixed the issues on the RT side with distribution motor, I have turned my attention to the LH side distribution flap motor.
Nano shows error as "Motor short circuit to 12 volt positive"
The motor moves the flap just fine from recirc to fresh.
I have unplugged the motor and substituted in a blend motor with a good drive. Works fine. Same error.
I found the 2 wires at the HVAC head unit plug and snipped them and attached motor directly to the plug.
Same error.
I have swapped in 2 different known good, tested working head units and same error.
What am I missing? Nothing in that circuit is shorted to positive anywhere???!

What do you get if it is disconnected completely? If there is nothing attached it can't be seeing a short to anywhere. Recirc motors are the same as the other blend motors except they don't have any feedback pot.

Sorry, I failed to mention that with the motor unplugged as well as with the wires going to the motor plug
cut at the HVAC plug, it is consistently reporting "Motor is short circuit to Pos 12v"
I am indeed trying a blend motor as a substitute as you had suggested on the dark side sometime back.

I did notice that since the HVAC only does a calibration every 6 or so cycles of the ignition that
with motor plugged in, and error cleared, it would stay cleared until it tried to do a scheduled calibration.
Now, it seems I cannot even clear the fault.
I do cycle the ignition after clearing fault as Marty suggested......