Hi folks. I'm new to the forum. We are having an issue with erratic blower air volume output on our 2015 Pathfinder SV. On initially starting, HVAC system works normally in both a/c and heating modes. After a period of time from minutes to hours, air volume output from all vents will quickly reduce to almost nothing with no real change in blower motor sound. Reduced air flow affects aĺl vent modes, recirc and fresh air, as well as dual and single modes. Blower appears to run appropriate to blower setting, just no airflow from vents. Output from rear passenger system similarly affected. Nissan mechanic has spent hours trying to diagnose. Cabin filter replaced, intakes checked for obstructions and blower motor removed and checked. Malfuntion will continue until car is turned off and allowed to sit for a long period. (Of note, issue first appeared some weeks after repair work completed for large stone impact to underside which caused significant damage to frame, oil pan, a/c leak, drive train etc.) Does anyone have any idea what could be causing this?