My ac does not blow any air through the vents after driving for 1/2 hour or more in 90 deg and above weather. If I shut down the ac it will then work for another half hour. I ran a test with the car in my driveway under thge same heat conditions with the ac on and no problems. I have been told that if the unit ices up that will block air flow. Also, water does drain from the vent. Any thoughts or similar problems out there?