Thanks for the replies. I did remove the bumper previously and got rid of all the gunk...and cleaned the radiators with a dedicated foam cleaner. But in 100 degree heat in traffic, the car runs uncomfortably hot. If it's moving, it's ok.
I found the link for Ben006. For those interested, here it is:
http://986forum.com/forums/diy-project-guides/61513-diy-manual-radiator-fans-control.html. I think I'll give it a try...