Main radiator fan not working

[lsupcar]

While parked for 20 minutes with the a/c on, the temp gauge started to go up to about the 9:30 position. As that has never happened before, I turned off the car and noticed some bubbleing in the coolant overflow resevior. When the car is moving, the temp gauge is always where it has always been, 8:30 to 9:00. I checked the radiator fan operation today with the engine hot, a/c on, and the auxillary fan on the drivers side was working, but the main fan was not working. Both fan fuses are intact, though the right hand fuse tabs were slightly corroded, but the fan still did not work after cleaning the prongs. I tapped the top of the relays but the fan did not come on. I have the shop manuals, but can not find a trouble shooting guide for the fan and associated electrics.
Any advice?
Bill