Electrical issue help!

[joelm96]

Pickup is a 1996 3500 cummins with 47re. Ok so the truck starts up quick and runs fine. However under 55mph if I turn on the ac it starts surging 2nd 3rd and od. When going 55+ if I use the horn or windows it downshifts and rpms go high

 

[MAC830203]

Start at the battery, grounds then the alternator. ChEck for volts.