I have a 95 lexus es300 that runs hot only when you turn on the a/c. Runs fine and at normal temp. As long as you don`t turn on the a/c. It has a new radiator and a new thermostat. What are any other problems that can cause this?
Stupid Question, but have you checked to see if the electric fan (if equipped) turns on when you turn the A/C on? I'm not too sure how Lexus operates, but usually there are electric fans that help keep the car cool once the A/C turns on or when the Car reaches a certain temp. If you notice it doesn't come on, check for fuses if they are fine then try jumping the fan to a constant power source (battery) and if it turns on then there is a bad thermo sensor. Hope this helps.