help me out

so how do i do that ?. any step by step or clue

There are three servo motors under the dash, accessible (barely) from the passenger side of the car. The servos control the heat/cold air, the other controls the air mix (whether the air enters the floor, vent, combination, etc) and I actually forgot what the third one does (could be fresh air vs. recirculate. I have not seen anyone ever post a problem about this servo). Most of the servo issues appear to be with the hot/cold air mix. The servo basically wears out (you may have heard a clicking, crunching, or grinding noise from behind the dash) and the control arm that will move when either heat or cold air is called for does not move. There are videos on Youtube (try typing in "how to change servo on Lexus IS300) and I think Club Lexus had a good tutorial. I just changed my heat/cold servo, and it's a pain to get at. It helps if you have a set of sewing screwdrivers, as they can fit in between the piping and are small enough to allow you to work. Good luck. It takes about 1 hour to change out.