hello trying to get some feedback on my 73 mustang 351 cleveland i am having (what i think is an electrial proublem when the car is running with nothing turned on i am reading 14 volts(that is great) the when i turn on the headlighs the volts drop to aroung 13-12 volts(not too bad) then with the headlights still on when i turn on the fan motor (for the a/c or heater) the volts now drop to 10.5-11 this seems really low the voltage regulator and battery are brand new...when i turn off the heater or headlights the volts then return to 14 volts just wondering what i could look for or try...also on the stater relay(on the passengerside fender) there is a small(fuse or relay)attached to the starter relay post can anyone tell me what that controlls thanks rick at oldstangfan@yahoo.com