A/C and Fuse Query

1989 Honda Accord LX-100k.....car is in excellent condition but like any machine little things can become huge problems.......my a/c has a tendency to emit cold smoky air thru the middle front dashboard vent. the air is ok but this seems to be an ongoing ocurrence. what would or could be the problem..would like to know before this minor thing becomes a big one ALSO what do i do to get the overhead light to work..is it possible to use a multitester to check the fuse / wiring ,etc? is that fuse connected to other devices ( i.e lights, etc)...please advise on both queries.thank you!!

the "smoke" you see . . . .Its just like going outside on a very cold day & breathing, just the opposite for the A/C

Have you tried replacing the bulb?
Is there anything alse not working(elec.) wise?
Fuses usually control more than 1 item

Is the switch on OFF? swith it to ON or the Middle for doors only