Low voltage

[Art99SS]

I have a 1999 Camaro SS A4, free mods, ftra, and cutout.
I only get/or notice this problem when I drive with the ac on. As I am driving all is fine, until I stop at a red light, then I notice my blinkers slowing down and the volt gauge dropping.
Sometimes I will put the car in neutral and the volts go back up alittle.
I took the alternator in and it tested good. Anything else I can check? I have a craftman digital multimeter but havent learned to use it yet. Thanks

[sunsetorangess]

How low does it go? Its normal to drop a bit when the compressor is cycling. Make sure your battery terminals are good and tight and clean. As far as your multimeter, switch it to "DC" and put one leak on positive, the red one and the other lead on a ground or negative, "black lead".
J