2001 Isuzu Trooper 2001 isuzu trooper electrical issue

When I use my a/c and radio my battery dies. It is not my alternator as I put a new battery in and did not use those 2 things and the truck drove fine when I put the meter to it at the house it was reading 13 amps and I drove for an hour and change(12 volt) battery. When I come to a stop the ac blower dies...it does not work at all, when I drive it blows air...certainly not cold air. What is going on with this thing??? Please help!
(2001 isuzu trooper 3.5l 4x4 automatic 200,000 mi)