My lexus gs300 cuts off whenever the fan comes on ??

Yea the a/c works I'm talking about the engine fan that keeps the engine cool

Yeah, i know what you are talking about!!! Does the engine stall if all heat a/c controls are OFF? You see the a/c compressor and the cooling fan work together with a/c on!!!! If there were a problem with the compressor it could account for your problem!!!

!! Does the engine stall if all heat a/c controls are OFF? Yess it do

Has it ever been tested with a professional scanner while test driving, by a qualified mechanic?

Yes and they say they can't find the issue remember I had this car by 6 different Shops with all different tests none could fix it

Yes i read that!! If 6 'MECHANICS' that can run diagnostic tests cant find the problem, be hard to help over the net....All we can do it offer a best guess...! Bye.

If I put the heat on and it's on high the car do not stall