Blend Door Issues

[EnZI]

I have a 2004 RX 330 with 66000 miles. I have problems with the A/C. The Driver's vents are blowing hot air while the Front and Rear passenger vents seem to be blowing cool air only when the temperature outside is about 72 degrees. I took it in for the repairs and the mechanic told me he suspects I have a blend door issue which would cost about $1000 to fix. He did not perform the diagnostics (which cost $180)Before I invest such an amount can anyone offer susgestions?

[code58]

EZ- Don't mean to put you off but there is a lot of information on the blend door issue and how to deal with it on this forum and the other popular Lexus forum. Can't imagine where the $1k price is coming from. That seems excessive to me, to the max! The "Search" feature is your friend.