azhari,

the cooling fan switch you refer to usually fail-mine failed at 100,000miles plus and i changed it and the car no longer runs hot in traafic.

the electromagnetic clutch can fail-if you have a haynes manual for your car,then i suggest you look at it for more info on the fan clutch-there are a couple of electrical contacts below the cooling fan-have you checked the wiring that leads to the fan clutch?