I have a 1990 that is wanting to overheat if it is left idling for a short while because neither of the cooling fans are kicking on at all. What would be the main cause for this? fan motor, relay, etc.

 

How hot? One fan comes on around 226F and both when the a/c is on. Check the related threads this subject comes up often. These engines like to run hot and many people get nervous about it . If the temp. goes over 235F its time to break out the volt meter.Bad motor or temp. sensor Good luck.