One of my Lexus's is a 2000 RX300, I found your diagnostic instructions very helpful, I got a 00 code(no problems) the problem is that when driving with the heat on and blowing warm towards the floor, cold air blows softly thru the 2 top right & left air conditioning vents, not thru the center vents, after driving for 15 to 20 minutes and its cold outside, you notice that your hands are cold, would appreciate any help.Also, all other heat/ac/ def. function correctly.

 

Mode servo is responsible for directing air thru different vents. Take the system out of Auto and set the mode to your desired setting and turn up the fan. See if the air flow matches the setting. Then investigate the servo or the arms that operate the vents.

Search on 'Mode servo' .. there is ample info on it.

Salim

 

Thank you, will check it out today

Randy

 

It does, doesn't it? Just like wife's 99 RX300 did? With nothing wrong with it?
Welcome to the world of Denso climate control unit. Look online. There is major gripe about Denso making them with mind of its own and not willing to cooperate with what user wants. It's like they made them guided by lawyers, with only concern about windows fogging, that's it.
Maybe you'll somehow fix yours. I gave up on ours, simply told wife to point those vents at windows winter time. And surprise - same Denso did same on out 07 Camry. My 12 Highlander - same thing. I keep airflow through those vents shut when it's cold outside.
Too much "smart" electronics beyond user direct control.