I've seen several posts regarding problems on the passenger side. This problem is on the driver side.
Problem --- unable to adjust temperature on driver side.
Symptoms - may appear to be defective heat or defective A/C on driver side only (depending on the position of the mix damper).
Solution -- replace mixer damper assembly servo (this controls the mix of hot and cold air on the driver side). This is a dual climate control, so each side has dedicated dampers
This is a 2004 RX330.
So, if unable to change "where" the air coming out, the damper with the red arrow would require replacement.
If unable to control the temperature, the damper with the blue arrow would require replacement.
I will post pictures, after I repair my own. I'll be replacing the damper with the blue arrow.


This photo was taken with my feet on the drivers head-rest and my head pressing the accelerator.


I hope this helps someone!

 

I'm in for updates. I've read countless threads on replacing the passenger side servo (which i did today.) but not much on the drivers side. I ended up ordering the wrong part from RockAuto, and it doesn't look like they have a part number for the drivers side servo, so I'm looking for ideas (other than the dealer $$$).

Keep us posted.

 

Hi, allenclan1! Can you explain how did you replace the one with red arrow. Step by step. If you did it. I have exact the same problem; right side able to change temperature but left blowing cold air no matter what is on display. Thank you! I check an Amazon and Ebay about the heater blend motors, they are $25-$30, but main one is much much more.