Intermittent Pump / Purge Noise - 2008 Honda CRV

I'm getting an intermittent pumping noise / pressure release noise (who knows???) coming from the dash area. There does not seem to be a pattern to it. It happens with the climate controls on and completely off (trying to rule out some sort of damper).

The following video link has the sound happening at the 8 second mark in the video. Just not sure what that "growl" could be??

http://youtu.be/VUUluSh5WGk

Any creative thoughts / ideas?