Well I went to the sticky and found the write up on cleaning out the hvac box,I was wondering why I had so little heat coming from my vents in the morning,well now I know! Holy cow! I pulled a godawful amount of leaves and other mess out of that box,now the thing blows air like crazy!Anyone who has never done that I totally recommend checking it out.

 

What if you just have the "kick vent" on the floor and no AC or vents, just the defroster vents up top with "heat" and "defrost". Can you still clean it out?

 

The box will still collect the crud regardless of the AC or Non AC. Clean it out and it will make a difference.

I cleaned mine out but all I cut was a large hole with a hole saw and filled it with a junkyard grommet.