Ignition Switch Heating Up

I have a 87' GT that I completely restored about 7 years ago.  Shortly after the restoration I was driving one day and I noticed smoke coming from the steering column.  I pulled everything apart and found that the ignition switch connector(http://www.laurelmountainmustangparts.com/store/images/FM-E1003C.jpg) had began to melt and the two yellow wires were starting to turn brown.  I replaced the ignition switch connector and this repeated 4 more times.  I eventually got too busy to mess with this and unfortunately parked the car.  I have decided to bring her back to life and this has started to show its ugly face again.  I once thought that there was a correlation between running the AC and it heating up, but after trying it again I am not sure.  Any advice is welcomed.