Would a sign of needing a new battery be, when I put on the air and something else the car starts vibrating? Could it be that the things that I am using are pulling too much power from the battery and causing it to make the car vibrate?

 

if it starts vibrating only when you turn the ac on your ac compressor pulley could be bent or somthing its probobly got nothing to do with your battery

 

If the pulley is bent, it would make the noise/vibration all the time. The AC belt is always turning, the compressor just starts compressing air when you flip the switch.

 

maybe its internal damage to the compressor

 

I have the same problem. But with me, I turn on the rear defrost, and the car seems like it is using too much of a load when I am stopped at a light. The idle gets pulled down, car vibrates, etc. When I'm driving, it's fine. My alternator puts out 74.4 amps, 14.37 volts, and I just got a new battery. I can't figure it out at all.