I noticed that the headlights on the car sometimes are brighter and sometime its not as bright. i noticed that when i had halogen before and its doing the same even with HID. also back in summer i also felt that the AC is not as cool sometimes.

anybody had similar experience?

 

huh shouldnt be. you should be getting 13.8v test the battery to see if its still holding charge. could be half dead

 

ohh forgot to add, checked the voltage and everything it usually float around 13-15 sometimes

 

if it hits 15 it take it in. the alt voltage regulator might be fried. normally its 14.4 max but gm has it limited somehow to 13.8 all the time other then right at start up