Having problems with headlights flickering. The interior instrument lights only work when on high they dont dim anymore. the power seats quit working. when you turn the fan on the turn signals slow down and the voltage gauge drops almost into the red. turn the fan off and the signals speed back up. Any ideas im sure it may be a few things

 

I was having a similar problem so what I did was change the battery cables which was really easy and replaced the alternator. After doing this my problems with the lights and other electrical issues went away.