Is one of the radiator fans suppose to run constantly all the time or only run when its hot? It seems like the fans on my gs300 only run when I turn on the a/c and if i turn the a/c off they both turn off and stay off. Is this normal or is there a problem with my gs?

 

The fans suppose to run whenever the temp of the radiator is reach to a certain point, and the sensor will kick those fans on. there is a temp sensor at the bottom of of the tank toward the driver side. B4 you decide to change it, run the car and watch the the temp gauge to make sure it reach in the middle, also watch the fans which it should come on. It may not be on right away, but if you let the car run for awhile, those fans will kick on if the sensor it's working. Others might be able to chimp in as well. Both fans don't constant run all the time, it runs only when it reaches to a certain temp and the sensor will kick it on accordingly.