my car over heats but if i turn on my airconditioner the fan will come on t?

Does it overheat in normal driving or only when sitting/driving slowly?
Does it drive OK otherwise, not losing oil or water?
It may just need the cooling system (especially the radiator) drained, flushed clear and refilled.
Check the thermoswitch on the rad which controls the fan.
What make, year and model of car is it, some makes have recurring problems.

bagnall
October 2009