Turn defrost on (or off) for a target window — front, rear, or all. Activating defrost for the **front or all** windows is never a single call: policy requires a fixed set of automatic supporting changes (fan, airflow, AC, and the window-closing that AC-on forces) to be applied in the same turn. **Rear-only** defrost has none of these requirements. Sometimes the target window is unstated, a control needed for the cascade is missing, or a window position can't be read. The same method handles all of these.
