No air or heat
 

I have a 2017 F-150 5.0 w/23k miles. When you get in & start it up there will be ac/ heat blowing out for like 5 mins then it slowly fades to nothing. It doesn’t matter if it’s on heat or ac. Can still here the blower going but no air movement at all from defrost, dash or floor.
I removed to filter just to make sure it wasn’t clogged up & the blower blows all kinds of air out the acces for the filter.
I know it’s not freezing up. The compressor clutch is engaging & disengaging like it should.
So I know there are all kinds of smart individuals on here.
Help me out. Is it blender door? A vacuum problem. I’m lost.

What type of climate control system? Manual or automatic, single or dual zone?

it’s a manual system.