My IS300 overheated and crack my radiator. I'm lucky that no damage to my cylinder head ang engine block.I installed a new radiator, hoses and t-stat. I ran the engine for 10 min. the coolant temperature still going up high and radiator fan is not coming on. I jumper the wire connector that goes to the fan switch and both radiator fan came on. I thought it was the fan switch that is going bad. I bought a new fan switch and tested it with hot boiling water. The switch closed @ 215 degrees. I installed the switch and ran again the engine. The result is the same, temperature is going high and cooling fan is not coming on. I also tested the heater inside the car and it is working. Please help :-(

 

Did you bleed the system? An air bubble could be still caught in the system making it not open up the thermostat. To bleed it, raise the front end of your car, open the radiator cap and start and run the car for until the car is hot and the fans turns on.

 

 

Ah, I've done that before....glad you fixed it .