Voltmeter rapid fluctuation when A/C turned on

Voltmeter stays over 14 volts but fluctuates rapidly when the A/C is turned on. It goes to a solid 14.5 volts when the A/C is turned off. The A/C works fine it is just the voltage jumps around. I checked it at the battery with a digital voltmeter and it shows the same thing. Does anyone know where/what to check?

Also noticed that the voltmeter drops and goes back up with the turn signal or just drops with the brakes applied.

Forgot to add it is a 2002 2500 4x4.

Voltmeter on what? What's wrong? Why are you doing this? The post seems random, but help us understand what the question is.

Check your ground wires as I remember on the  drivers side frame a couple grounds tie together  clean and retighten check battery connections tight but don't over tighten also on my 2500 back on passenger side up above the exhaust pipe is a junction box that the tailight turn signals etc join up. There are 4-5 plugs that snap in to the junction box I found a loose connector in one of the plugs you could see it was discoloedit was a ground I cleaned and adjusted it and did buy replacement module ??45$. My problem was twilight a and turn signals did not work right and if you we're on cruise and tapped the brakes the cruise control would drop out don't forget a bad battery. Can cause trouble too my volt gauge would pulse from like 12-14 and that went away with new battery
Got change

Thanks I'll try checking the ground and post if that corrects it.