My heater fan, at lowest speed, will make a similar sound you described, especially going around corners.

If your car has climate control, there is a small air pump that sucks air from the overhead map lamp that calculates temps. The pump is located in the side panel, passengers right foot, that also will make similar noise, when bearing get dried out and wear.

Just two things I can think of of the top, but you should be able to determine easily by turning off the CC unit.