I rewired an ac unit that had caught on fire inside the unit and its running good. The capacitor and ptcr was burned, the ptcr was almost completely gone. So I get this thing running and the evaporator is cool and condensor is hot with fan running great. I thought I was done. So as I sat in the house for an hour it seemed like it was cooling down kinda slow. I went and checked the vents in the house and the airflow in them was little or none. So Im thinking this entire problem was caused by this ac unit running 24/7 for half the summer. All the air is being dumped in the crawlspace from broken ducts (due to old house sinking issue ) and coming out the crawlspace access. I fixed 4 disconnected ducts and taped all the ducts that I could but I still have a good deal of flow coming out of this crawlspace access. The vents inside are working halfway decent and the unit is not running constant like it was. So here is my question. Do I close off the crawlspace access? Ive read some pro's say never close it, some say go ahead and seal it off. There is a reason I cant check/fix the ducts in some places, on one side of the house the foundation sunk almost to where the joist are 6 inches off the ground. The sinking has been fixed years ago. It seems from reading about crawlspaces the concern with blocking it off is moisture. With all that leaking in there wouldnt it stay dry if I blocked it off? It so dry its almost sandy in there. Ive heard of the radon gas problem but Ill test for that. On and 85 degree day the crawlspace was 60 with the house at 72. Close it off? Start digging? What do you all think I should do?