Mystery vents in a 1972 condo in bathroom and kitchen

[Janice R.]

Hi all,

Here's the story in my strange and possible useless (?) vents:

1.  There's no fan or window in the bathroom.  There is a 6" x 6" vent about 6" by the vanity light fixture (on the wall), in fact, it covers the vent.  The metal is pitted where the vent is, which seems from the humidity.

2.  The kitchen has the same size vent above the cabinets.  There is a fan in the microwave so I'm less worried.

3.  The A/C and heat comes from 2 PTAC units, one for the living/dining room and one for the bedroom.

4.  So there must be a duct in the ceiling, however, I'm not sure if I can add a fan using the bathroom vent.  

My goal is to add a fan to help the humidity but if not, a ductless fan would be ok.  I'm hoping that anyone has seen this configuration in an older condo.

Thanks !!