My fog lights just stopped working on me one day, totally confused me. I changed them out, changed bulbs, nothing. Ended up being the switch. Odds are though that if the light is coming on that it is working fine.
Do what PaulG is suggesting. Can't hurt right?
(I was unaware that there were vents in the back? I just thought it was the grid itself.)
'94 Green MX6 LS - all red tails, FD's, bone stock otherwise.