On my truck, I do have a large power amp with a 50 amp fuse and a fan from a Taurus that pulls 30 amps when on...although, even with both of these off, my blower motor in the dash for the A/C, when it's on, draws enough power to drop my gauge below 13. The alternator should be fine, battery is at least 1 1/2 years old. I know it sounds like the ground, but the ground coming off the blower motor to the firewall is down tight. Is there another ground I should look for? Has anyone else had this problem? And, as on off-topic, I'm going to drive to Estes Park, CO from here (San Antonio, TX) in 2 weeks with my 31's on so I turn 2,000 RPM at 65. My question is, would it be a good idea to install a tranny cooler, or is it not really necessary?