Clip Jam not playing when power cord plugged in

what are you plugging the power cord into? if it is a USB port on your card it may be trying to mount as an MSC device. If the Jam makes a data connection it can not be used as an audio device. You should be able to get a USB AC charger that plugs into the cigarette lighter port and use that to charge the Jam. If there is no data connection it can be used normally while charging.