if you were in a room with no ventilation (ie shut and sealed windows, a door with an air seal and no air vents)

• in zero gravity
• OR in a room with a heat index of 90°F+ (heat index not temperature)
• OR in a room that puts you in danger of hypothermia (especially if you have heart issues at the same time

it’s possible that a fan might exacerbate oxygen deprivation or the affects of the extreme temperatures

If you have normal windows, a gap under the door and a vent of some kind then it simply won’t.