The radiator fan is not working properly causing the car to overheat in idle.

On some models there is a variable fan speed control module that is common to go bad. You need a factory scan tool to command the fan on all speeds and verify voltage in and out of the module to the fan motor. If you need help please feel free to call or stop by Curt's Service. Sincerely, Your Curt's Service Team 248-545-0500