2002 Kia Sedona Radiator

Engine Cooling problem
2002 Kia Sedona 6 cyl Automatic 111000 miles

I just had a radiator replaced on a 2002 Kia Sedona. It was almost 400 dollars total. I drove it back home and the temperature gauge is still going up like it's gooing to overheat. The mechanic said he checked the thermostat and said it did not have to be replaced. There is coolant in the car and I can see that it is full. What else could it be? Also when I drive, it sounds like there is a fan that is constantly on.