This is the system in a typical San Antonio slab home: the unit lying in a 140° attic, R-8 flex reaching every room, and the condenser on a pad against the side wall. Switch between cooling and heating, drop the roof and walls away, and click any marker.
Warm air is pulled out of your rooms through the ceiling return, cleaned by the filter, chilled across the evaporator coil in the attic, then pushed back down through insulated flex to every register. The condenser on the pad outside dumps that heat into the yard. Break any link and the whole loop suffers.
