i am also pretty sur it is the coolong fan switch.
my car used to overheat in idling conditions in traffic.
i replaced the cooling fan switch-mine was a 3 pin one, as my car has a 1.8 litre engine.-problem solved
if you get the faulty switch out and type in the part number which is stamped on it, into the fast lane online catalogue website -you will be able to see a picture of what you can order-it is not expensive but as russ says your switch may be a 2 pin type as you might have a 2.3 litre engine.