As fokion said- DO NOT let her overheat. as for the problem- first check the radiator. it can get clogged with sludge - one of the symptoms is that your collant reservoir - the small coolant bottle with the blue cap that is located on the right side of the radiator will be empty from any coolant. so get the rediator well cleaned- unbolt the bottom coolant hose and insert water at high pressure. you wont believe what amounts of mud and dirt will come out of there!! then fill up with some quality coolant. i did it twice to make sure my system was water free because regular pap water can corrode your engine. if that does not work- replace thermostat. also- check your fan- and fan clutch. Also- as fokion said- why not consider a fan swap to an electric one?
better yet- if you dont want to do that-you can also install an extra fan up front next to your AC fan.