it was just a regular moring on my way to work. started my car it started up just fine. then i tryed to turn on th ac and everything died just becasue the ac go turned on? now theres no power at all! i put the key in i heard the beeping and thats all no lights no starting and no radio at all? i just bought a brand new battery so i know thats not it plus i just check it and it saws 12.5 so im not sure what to do help!!! its on 1992 rs 305 v8.

 

probably a bad battery cable or connection-check where
the pos.cable connects to the starter solenoid and where
the neg.cable connects to the engine. The extra load of
two fan motors and A/C clutch activating opened up an
iffy connection somewhere.

 

i just replaced the positive battery cable. maybe i didnt tighten it enough but it has never done this and i replaced it like a month ago.

 

Also check the wires/fusible links that come off the
positive stud on the starter solenoid and go to the
wiring harness-if not loose or broken,they can wick up
moisture and corrode internally-especially if you are in
an area that uses salt/chemicals on roads in winter.