TookGS to my neighborhood mechanic, and he told me good friggin luck. He's top notch, but he knows when to walk.
Symptoms: I have minimal AC(Good volume / not very cold)coming from the drivers side and warm air from the passenger side, even in dual mode, with both set at 66 degrees. Even in non-dual mode, warm air still comes from passenger vents. Freon (or whatever its called today) level is good and compressor kicking in. Can't get the driver side to get any cooler, and can only get thepassenger side to get hotter. It's hard to look cool in my GS when I'm sweating like a pig, and sticking to the leather. Another hot day in LA awaits. Appreciate any suggestions...

Tim

What happens when you turn the heat on all the way? If you put the heat and temp all the way up (I know, I know...I will be hot!) ... and then bring it all the way down. Does it change anything?

I had a problem with my old car (not a lexus) that there is a damper door that adjusts open to let some engine heat in and closed to stop the added heat mix. My damper door got "stuck" and didn't close all the way and mixing hot air with the cooled air. If the passenger side of the car is warmer the drivers side, I would think that a door that lets the engine heat in isn't operating properly. This is something that Lexus should be able to fix.

If the car's engine is cold, is it cooler in the passenger compartmentthen when after a while when the engine heats up? Does it make a difference if its in Recirc mode or not?

Good Luck!
Rick

Expansion valve sticking. Not too expensive, had one kick my @&* for 2 months. Freon level always good, no leaks just stops cooling. Sometimes starts cooling out of nowhere but not for long.

Although that is a definate answer to tnat type of problem, have a good HVAC tech hook up manifold gauges and see whatr high and low pressures are. Like I said, a good and EXPERIANCED HVAC tech will be best when he notices thing like: to high on the low side but normal on the high, low on low side and high on high, and all other possibilities.

Another problem is the airbox. The blend door and also other doors. Many doors. Dual means you can have to passages so that a vent can be fully open to the evaporator for the driver and partiall evap and heater core for passengers. It is great.