Why should the technician confirm the heater control panel and ducts direct airflow correctly (floor, defrost, vent) when servicing the HVAC system?

1. Incorrect mode-door operation can send heat to the wrong outlets, leaving the windshield un-defrosted or the cabin cold
2. Duct direction has no safety relevance
3. All air should always go to one outlet
4. Mode doors only affect the strobe