headlights dimming, loud humming noise.....

[niko52]

Every time I use my air conditioning or my defrosters my headlights dim higher and lower every minute or so. Also, when I turn one of those things on, my car makes this loud humming noise which gets louder the higher I put the fan. At first I thought it was the alternator because the headlights just dimmed, but once it started making the humming noise which just recently started, I'm not sure what to make of it. When I put my blinkers on today, it wasn't just my blinkers that blinked, I noticed my interior lights including the radio, blinked slightly as well. Any ideas or advice?

[devildoughnut]

The same thing was going on with my lights and it was just old spark plugs. If you don't know how to ckeck just replace all 4. They're pretty cheap. Don't know about the humming though. Take care of one problem at a time I guess... who knows maybe this will take care of that as well.