Turned on defrost this morning and cold air blew out of the driver side and hot air blew out of passenger side. My regular mechanic said he does not work on HVAC and sent me to a guy who thought it could be the actuator and would require taking the whole dashboard out to replace and would cost $1800 minimum provided that the dashboard didn’t crack which he said was a distinct possibility in such an old car. He did not do an actual full assessment. I am wondering if I should take it to the dealership where it’s $280 for the assessment to pinpoint exactly what’s wrong. But wouldn’t a full scan reveal the issue?

 

If lucky it could just be low refrigerant, but may be the infamous blend door actuator. Do not waste $300 to have the dealer tell you the same thing and then want to charge twice as much as this 16 year old car is worth to repair it.
See these older threads and then look for another independent mechanic who specializes in Toyota/Lexus (same mechanicals) or an A/C specialty shop. This has been discussed many times.
This Lexus Toyota shop in Minnesota posted this great explanation of the issue and what is involved to repair it with photos: https://carspecmn.com/rx450hrx350-no...de-blend-door/

These threads will educate you on this issue: I found them all by using the search term actuator which is why it appears in red in the search results.

The first link is from someone who managed to replace it without removing the dash although that did not fix their problem! which was the wiring harness.

https://www.clublexus.com/forums/rx-...amplifier.html

​​​​​​https://www.clublexus.com/forums/rx-...ide-front.html
​​​​​​https://www.clublexus.com/forums/rx-...or-2013-a.html
​​​​​​https://www.clublexus.com/forums/rx-...-one-side.html
​​​​​​https://www.clublexus.com/forums/rx-...vo-broken.html
​​​​​​https://www.clublexus.com/forums/rx-...side-heat.html

 

Thanks I scanned it and got codes B1442 air inlet damper control servo motor and B1446 air mix damper control servo motor circuit (driver side).

Are there separate servo motors for driver and passenger sides?