The mechanical fan is not the one that is on the driver side (where the exhaust manifold is), that's the electric one. I'd also suggest replacing the mechanical fan clutch though. Cheap, easy to do, and great reassurance.

mine was over heating too. only at idle. i basically over hauled my cooling system for about 115 bucks. new mechanical fan clutch, new thermostat, new water pump, clean and flushed radiator, fresh coolant. shes perfect now.