The red arrow indicates the area where we'll focus our cleaning efforts.

Start by powering the fan on. Then, switch it to the highest setting.

Use compressed air aimed at the crevice toward the back part of the fan (where the arrow is pointing). Keep shooting compressed air in at various angles up and down the slots until dust stops coming out.

Try the heating function to see if the error is still there. If this doesn’t work, proceed to the next steps.