I've got an 04 x-type and every time I turn the AC on the car dies....I could be going down the highway or sitting at a light and it still does it.... Any suggestions on what it could be.... Car runs great when the AC is off

 

Use a multimeter and check volts as you turn on the a/c, if it drops, its electrical, could be wiring to the clutch, or a/c pressure sensor. if not, maybe a seizing compressor (not likely)

 

It could be a seizing compressor shaft, when you turn the AC on the clutch engaged the the pulley the engine could not pull the compressor so it die.