1994 dodge caravan and when its moving it doesnt overheat but when your stopped it starts to overheat and you notice the radiator fan does not come on is it the relay or?

It may be the relay or it may be the fan. Take a multimeter out and see what kind of voltage you are ghtting at the fan connection versus the realy. If you are getting voltage TO the relay and NOT OUT when it should, it's the relay. If you are getting voltage TO the relay and OUT of the relay then I would say it's the fan. You can run a jumper wire from a powered source and see if the fan spins and this way you know the fan is working if it receives current.