Overheating prob in my nissan vanette.?

my van water temp start to go up high til 3/4 when in heavy traffic with my aircon on,but when it turns off the a/c it will start to go down.it has no prob when running fast.the thermostat is already remove,it has already aux fan in radiator,the clutch fan is already fix,the radiator is overhauled,the water pump is new,aux fan in condenser is working,the bearing in compressor is also new,but still the prob occur when im in heavy traffic and when im in parking with my aircon on,but when it is off it has no prob in overheating,what should i do so i can use my aircon when im in park without fearing of getting overheat?my aux fan in condenser also working. i dont think i hv a leaking gasket,bec if i have a leaking gasket my oil in my engine would start to add or excess in oil measurement,but i always check it out and the oil is always at its level.