I have a 13 year old 2005 RX330 with 120K on it and the car had AC problem as followings:
1. generally it could not keep car cool as comfortable, especially when outside temp is above 85F, when measuring temperature on four air-outlets (front panel), two on passenger side blow out air about 70F, however the two on driver side blow out air like 75F. When driving under the sun with 90F outside the inside temp is very hot.
2. I searched online - almost everyone says it is a problem with blow motor/vent door actuator issue. However someone on this forum said she/jhe had similar symptom (with driver side cooler though) - the problem was fixed by only recharging refrigerant (sounds not making sense on surface)
3. I decided to start with the simplest way: refill refrigerant - only DIY I could do. I had hard time to locate "low pressure port" - "carcarekiosk.com" showing a video claims to be RX330 but it is not. I finally located the port at the low far back on the passenger side under the hood (need to take out the cover on passenger side first), with a black cap printed with a large "L" on it.
4. bought a can of AC Pro (20 oz) with a pressure gauge at a local PepBoy store ($50 but with a $20 mail-in rebate). hook up the gauge with the low pressure port according to the instruction - the reading was at very low end (not a complete "0".
5. took out the "safety spacer" on the can and screw the gauge directly on the can (piercing) and connected the end to the port, squeezing the trigger to start recharging - squeezing two seconds, shaking and reading the gauge, repeat until the reading get to 36 lb. Disconnecting the hose and put back the original black dust cap.
6. all four vent blow cool air - much colder than before - I have not measured if there are still differences among four vents. I don't care about that for now as far as the AC could provide a comfortable temp inside the car when outside is 91F.
7. hope this post could help people who has similar AC problem with RX330