Alta Vista sits between the Southside and Arlington Park, a grid of mostly 1950s homes on small lots with carports, screened lanais and slab floors. Ductwork in these houses often runs through soffits and interior chases rather than a deep attic, and original runs have usually been altered at least once. When airflow is poor in Alta Vista, the cause is as likely to be a crushed or disconnected run as a failing blower.
The neighbourhood was platted early in the twentieth century and built out mostly after the war, so the houses share a footprint: two or three bedrooms, a carport and a lanai under one roof line. Duct runs in these plans pass through soffits and interior chases instead of a deep attic, and a chase opened for a bathroom renovation rarely goes back together as tight as it was. That is where a good share of the airflow loss in Alta Vista starts.
Slab floors limit what can be done underfoot, so re-routing a supply usually means going up and over rather than under. Screened lanais are the other local wrinkle: a lanai converted to living space adds volume to the system without adding a return, and the room that was comfortable as a porch becomes the coldest room in the house. Where that has happened, a dedicated return and a supply sized for the new space are usually the correction.