Ok I'm going to try to explain this the best I can. My 94 gt will overheat only when the AC is on. I have replaced radiator,waterpump,thermostat 180*, and pulled off my underdrive pulleys. I also just fixed a code 564 with a new ccrm which was my high fan not coming on. I do not have milky oil, and no water out tail pipes or bubbles up from radiator neck or exhaust gas's out of neck. Also my overflow is not overfilling. I also have a voltage problem. I can drive all day without ac and voltage seems fine with 14.1 volts coming from the alternator which is new. After running AC for about 15 minutes volts drop to only 12.4 on the alt and the overheating begins. Also voltage on both high and low fan seem to be the same. I am thinking that when the ac comes on it is slowing my fan down. The AC blows cold but could it still be causing a big load on the car that could cause the problems? Any other suggestions would be great b/c I have no idea at this point. Also it must have been doing this for a while b/c when I bought the car the kid thought the alt needed to be replaced and he also gave me a new cooling fan motor.