Vehicle: 2004 Lariat 5.4 4-dr

When AC/heater source is outside, airflow to the vents is weak. Still there but .... weak!
When source is switched to recirculate, airflow through vents is strong.

I suspect some sort of blockage but have no idea what/where to start looking. Any ideas?

Thanks.

Bill Lee

 

BTT

Anyone?

 

Perhaps remove the blower motor and inspect inside the box? Im not too familiar with the setup, I’ve only had to change the resistor on my ac system.