Direct sunlight can add heat to the appliance and its surroundings. The installation guidance should be checked when a cooling complaint follows a change in room use or season.
What the observation tells you
A warmer door surface does not measure the temperature of the food inside. It is therefore useful to record both environmental changes and proper storage readings. Covering the fridge with fabric to shade it can obstruct ventilation and create another problem.
A useful next step
Use appropriate room shading without blocking the appliance's specified openings. If the permitted conditions cannot be maintained, seek advice about the arrangement rather than repeatedly selecting the coldest setting.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.