I have a 2001 Durango with a problem no one can solve. I can drive for about 60 minutes in the city then the engine begins to heat up then quickly goes to overheat. I have had the engine fan clutch replaced, thermostat replaced, sensor replaced, waterpump replaced, still happening. No coolant leaks can be found, no smell of coolant inside or outside the vehicle. I have over 127,000 miles on it run great for an hour. The air conditioning is not working I put in new coolent it worked for about 2 weeks and now is no longer working. I don't know if the AC has anything to do with overheating or not. I am about ready to drive it off a cliff any ideas PLEASE!