Leave the light where it is and drop some new ventilation straight down to the back of the sink.
I will disagree with Robert's "Any ventilation is better than none." But not in its spirit, only in that I can imagine there are situations that the system is as bad as no ventilation, so I am picking nits.
I have worked in the same darkroom since 1978, the last twenty years actually getting paid (university darkroom). Over that time I have seen the ventilation go from poor to a little bit better than poor, then to fairly reasonable. Nineteen enlarger stations, two sets of 11x14 trays. It can be big and roomy, or when all stations are in use, it can be small and cramped. About 75 hours of open lab a week -- so students should be able to plan and find time to work...but on the eve of critiques, the darkroom gets busy and the ventilation seem to be able to keep up.
The fellow that had my position before me conducted a health survey of the darkroom users in a successful effort to show that the poor ventilation was causing headaches. The old system had the exhaust vent in the ceiling drawing the intake air straight to it -- above everyone's heads and by-passing the chemicals. There was a steady exchange of air happening, but it was all happening up by the ceiling: not where the students' heads were at -- which was in the middle of the fixer fumes!
Ventilation systems that draw the air from over the trays then past one's head on the way to the exhaust are possibly worse than no ventilation. One might as well stick one's nose in the tray and breathe it in! Feeling the chemically laden air passing one's face does create a pleasant false sense of security that one is protecting oneself! BTDT. Fortunately in those early years of all-night printing sessions it never really bothered me, though my girlfriends knew where I had been all night from the smell of the fixer.
After 30+ years I can not smell fixer in the air. My nose is numb to it. And I seem to be more sensitive to chemicals in general, though I do not do much silver gelatin printing, mostly alt. I have acquired asthma, most likely from blow-drying the platinum/palladium salts on watercolor paper; kicking some of the pt and pd salts into the air. Not a common thing, but so it goes. Belately it has shown me that I should have taken better care and should take better care in handling chemicals and paying attention to ventilation.
That said, I admit I sort of like the smell of acetone in the mornings...
Vaughn