The vents for our a/c are supposed to open and close by turning something t hat I will try to describe - it is a small knurled post with a slot at the top, although the slot is large compared to what a typical large slotted sc rewdriver would fit into. Years ago I used to use a screwdriver anyhow as i t worked after a fashion but not any longer as the venetian blind-like elem ents don't move as easily. As a result, it takes a considerable effort to o pen the vents by poking a screwdriver at the elements until they are all op en.
There must be some kind of tool that fits around the knurled post and has a screwdriver-like tip but the previous owner of the house didn't leave it w ith us. Is something like that available for purchase?