dynst

I have a 2007 Lexus is250 been having a knocking noise coming from the passenger side when I go from cycled air to outside air, also when I try to go from cold to hot temperature it isn't getting hotter. Does anyone know which servo is going out and how to replace them? I know there are like 8 servos because of the dual climate. Been trying to figure out all the locations of them and how to repair them myself. Because Lexus is charging about 1000 to fix a servo.
thank you,