Weak HVAC air from head position

[onspeed]

Front upper air vents have weak air flow when I've got the blower maxed. It's not a blend door issue because there's no air coming out of the defrost or feet vents when I've got it on head only, and vice versa when it's switched to defrost or feet only. Almost seems like something is clogged? Whether it's on heat or AC (which is broken), it's the same, although I did clean out the AC evaporator like everyone says to do. Any suggestions? It looks like I'll have to take apart the dash to fix any problems?

'97 suburban, ~200k miles

 

[great white]

The evap core in the HVAC box is first in line for the fan and can often clog up with assorted whatnot (hair, leaves, bits of paper, etc), restricting the amount of air it can pass.

if your fan is good and there's no problems with the motors/doors, that's where I'd put my money.

My 98 was packed solid with dog hair from the PO. He had a chocolate lab and when I reached in there it was like a big solid furry mat. The Fan barely made a popcorn fat worth of a breeze.

You can carefully clean the core if you remove the blower fan and reach in the channel.

I carefully pulled the fur mat off the core with a couple plastic "sprunger" type tools (prying tools make of plastic for electronic work).

Then I used "scrubbing bubbles" on the core and let it sit. I used a VERY soft long bristle brush to agitate it and then used a gentle spray of water to flush it out. I put a tray on the floor and the rest flowed out the HVAC drain.

Worked like new after I was done.

 

[onspeed]

Did that a while back, didn't help much. It's only the head position that blows weak, the feet and defrost are fine.