air blows hard and cold when I first start car and for quite some time while running however if I adjust the temp or after temp has been met air will quit blowing hard out vents, you can feel slight air movement (ice cold even condensates, dry ice like out of the vents) if I turn it off (the unit) for about 30 mins it MIGHT come back and then die right back out you can hear a blower motor going but no air movement anywhere, any ideas or suggestions any help would be much appreciated thanks