My friend who built the harness extension and I did a lot of troubleshooting last night in addition to getting the buttons illuminated with a disconnect plug.
Took it all apart and plugged in the old nav system and air worked fine on both sides, ice cold. So think that may rule out the blend door actuator.
Inspected the circuit board and connectors on the harness extension, plugged back into the non nav controls and back to hot air on driver side. Unplugged the stereo and everything from the center stack and plugged the non nav controls to the factory harness in the passenger footwell and same result, hot air on driver.
That leads me to believe that it might be the non nav controls themselves. Didn't realize my GX was a carryover month (11/04 build), so I guess only thing left to try is to source a older part number non-nav controls and see if it works. Unless anyone else knows of something to try.
It's almost like the current non nav controls are not getting enough or the right signal to shift the blend door down to cold air because when we switched from the old nav controls that blew cold air back to the non nav controls, it wasn't as hot on the driver side.