So as of recent when I put my defroster on (normally only happens on the higher settings) My gauge lights seem to dim a little. Including the AC control Lights. Its not a huge difference in brightness but still noticeable. Is this a common occurrence? Or could it maybe be my alternator? I'm guessing it has to to do with my battery. next time I should check my volt meter and see.

 

take it by a auto zone or advance and have them run a test on it for free

 

When you turn on your defroster your AC comperssor comes on too, this is probably whats causing the lights to dim.(increased amp draw and drop in voltage) I assume this is when the car has sat for a while.....correct?

How old is the battery and are the terminals clean and tight? Have the battery load tested and the alternator checked. Also check all the grounds going to the chassis. Good Luck

 

battery is atleast a year old. Ill have to check to see if the terminals are clean and all that other good stuff. The car normally only sits at max 2 days at a time. I try to drive atleast every other day.