Still working on HVAC

[QB93Z]

I solved the problem with the AC blowing out the defroster all the time. (separate thread.) It was a vacuum source tubing problem. The air blows out the correct vent for each mode of the HVAC Controller.

Now, after replacing the failed Heat Blend Door Motor, I get heat when the temperature control is set low (60 degrees). The hot air blows out the AC vents. And I get no heat when the temperature control is set high (90 degrees). The not heated air blows out the floor vents.

When I select Defroster Mode on the buttons, warm air blows out the defroster.

I have verified that the Heat Door Control Motor works and moves the door. By removing the Blower resistor module, I have visually verified that the heat door moves when commanded by the AC Controller.

Any ideas?

Jim