It's what could be called a "MagicPak." The intake for the burner is outside, but behind the grill cover, typically, if not through the cover. The top 3rd of it is the heat exchanger and blower, the lower 3rd is the compressor/coil, and the lowest 3rd is filter and ducting. The compressor/coil/etc. is on a drawer type system. You can pull it out, swap it with a known good one, and slide it back in. The only connection is electrical. Same with removing the drawer, taking it outside, hosing it off, and reinstalling. The rest of it is setup like your house with ducting, etc.
Venting the closet is a fire hazard, therefore, not allowed.
Assuming the association does the maintenance on the unit and it's in a bedroom, do not block the door. If you put a dresser on the same wall, make sure there is enough space to pull the drawer out of the closet with the door fully open, maneuver around the dresser, and out the door of the bedroom.