Recently it got up into the 90s here in Florida. And ac is a necessity. I've noticed that, although the air coming out is cold, it seems that it's not transferring to the vents as it should. I relate it to a stock late 70s 454. Lots of noise but isn't really going anywhere. The air comes out of all the vents no matter which setting its on. But.... with each setting change, I can hear the doors moving. When switching to defrost, 90% air flow is directed to the windshield. On face/ feet setting, only 30% or so comes out and still blows 20% to defrost. I can hear the other 50% getting lost somewhere under the dash but can't locate it. Any ideas?