That cavity may use a fixed fan-cooking arrangement rather than a separate function selector. Its controls can therefore behave differently from the multifunction oven beside it.
What the observation means
Fan sound alone does not prove the heater is operating, and a cooling fan is a different component again. The useful reference is the tall oven's own operating description.
A useful next step
Use the correct shelf and temperature guidance for that cavity. If it runs audibly but cooking remains ineffective, record the setting and result without touching internal parts. Do not assume that copying the adjacent oven's control sequence will enable a missing function.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.