fkfemi

My Honda accord over heats when stuck in mid to heavy traffic This started not too long ago but now its very consistent i.e. everytime i am stuck in traffic it starts to over heat and the heat gauge in the dash rises all the way to the top which is critical. i have replaced the coolant in the are and the radiator is not leaking. The funny aspect of this is when the car starts to overheat and i turn on the air conditioner it stops over heating and the gauge goes down....this is weird and i can explain it....can someone help!!!