my car is overheating/mechanic sed that i need to replace fan clutch

Viscous coupling fan could be the problem it is easy to test, it should spin relatively freely with engine off as the radiator gets hot the gel in the fan hub expands and locks the hub making the fan cool the coolant in the radiator. At freeway speeds the engine doesn't rely on the fan hub to cool the engine rush air through the radiator is sufficient to cool the radiator if the radiator is working efficiently. Make sure thermostat is good, head gaskets are OK and radiator is working efficiently after repair.

In traffic your van is getting hot right? The fan should begin to lock up as the engine compartment gets hotter and the fan will spin as fast as the engine until it begins to cool down again. If your unsure you can always stop in and we'll show you. Happy Holidays.