I have a 2000 RX 300 with 136000 miles. The issue is the air only comes on when the setting is set to max cool. Any other setting and the heater runs all the time. Any ideas? This is my first post so I'm not sure how to find similar issues that have already been posted. Thanks

 

Try resetting the ecm via a scanner. If you do not have access to one, disconnect the negative battery cable for a while. (stranger things have been cured from doing this. Hi tech electronics) If that doesn't work, maybe your servo motors are acting up. Also try an a/c diagnostic test. (do a search here for that)

 

Welcome to Club Lexus!

I'm inclined to say it's the air-mix servo that's being a bit lazy. But, I'd wait for other opinions from the more knowledgeable folks on here.

 

I think servo motor also. Does it make any clicking noise when ac on?