Sounds like the alternator isn't charging the bat. If its on 9 it probably won't start again until you charge the bat. Check your wire connection at the alt, trace those wires and check any fuses in the line. Mine did this about a week or so ago and it was the fuse in the alt wire. If all connections are good, I would take your alt to your local auto store and have them test it. If you mean you left the ac compressor hooked up and drove it and the volts dropped, it probably is putting a strain on the alt because the compressor is locked up.. look at your compressor, there should be wires coming off of it with a plug, UNPLUG IT. This will bypass your compressor so you can drive it, but you wont have ac and possibley defrost. You need a new compressor if its locked up. reread your post and sounds like you need to unhook your compressor until you can get a new one. Mine is out in my car.