Correct, the air registers are open. Air will blow for awhile, then
stop for 10 minutes to many hours. Sometimes I will shut it off for 20
minutes and when I restart it might work, might not. I'm trying to
find a pattern but have not been successful yet. Closest I can tell it
may be related to if the defroster (A/C) is running or just the heater.
It seems that something may be freezing over and not allowing an
internal door to open -- is that possible? Is there a sensor that
might be causing this ?