SNAKE BIT for sever days now

[ole dollor]

here I thought I knew every thing , and now I found out I don't.... ole dollor has an electrical problem and it has ate my sack lunch. started off ,it did not want to start, my son called and told me it that he had trouble getting ole dollor to start , but he checked the battery connections and tapped on the starter and it fired right off, I told him I would come to Lubbock the next day and we would check the starter , he called the next day and advised every thing was working good, then the next day while driving to work all the lights went out and he he ran on the battery the rest of the way to work. he advised that he would get a ride home and we could check it on saturday , went to Lubbock on saturday and started checking everything . charged and check the new battery , everything good, checked wires on new starter and it starts fine draw is good , alt I rebuilt about 3 or so years ago , not putting out anything, called and got new alt. put it on and nothing , checked more wiring and every thing looked good, got another alt. nothing , checked more wiring , found that the exciter wire was dead , jumped the exciter wire and alt started charging, still cant find why the wire is dead, told him to bring it to me sunday. he got here today and showed me that it working fine ....but to kill the motor he has to turn the key off and turn the a/c on and then the motor will shut off ??? fellow members I need some help. this is a hair puller. any body got an idea..... SNAKE BIT Don