Mini-split not heating? Start with the safe checks.
Before you call anyone, a few checks are genuinely safe to make. Confirm the unit is set to heat and that the target temperature is above what the room currently reads. Check whether the indoor filter is dirty, and whether anything is blocking the airflow around the outdoor unit. If the setting is right and the airflow is clear but the room still won't warm, that is the point to arrange qualified service rather than opening the equipment.