I noticed that my voltage at idle when stopped at a stop light will drop as low as 12.2 with the a/c on.

I tried swapping alternators just to see if id see any difference but the voltage still drops with both.

Keep in mind this is only at idle, once the car is being driven voltage peaks between 13.7-14.1

I usually run electric volt meters on all my cars and this is the first thirdgen ive had that drops the voltage that low at idle, kinda worries me so im wondering what all i could do to remedy the situation?

Im considering running new grounds throughout the engine bay, but not sure if this will help, anyone have any ideas as to what is causing this?