1992 Chevy Stepside Battery won't charge

My 1992 chevy truck had a bad ground wire from the battery. It broke off and the engine died. I have replacet the negative cable and ground wire. put a new battery in and a new alternator. After driving the truck about 40 miles with A/C running the truck would not re-start the battery was drained. what is causing the battery not to re-charge.

G. Kusak