Was informed that there’s insulation in the vents so they wanted me to go under the house to look for any penetrations half of the duct system is inaccessible I did find one hole in some 6 inch flex, but I don’t think I can get past the beam to get to it. can’t see any other holes. But the backside of the house is very tight to the ground. The only way to get back there is pull the flex out and redo the ductwork.