If your fans are working as designed, then the AC should be able to cool the car at idle. There's not much different between your car's AC and a Buick's. If you're getting no cooling effect at idle, something is wrong (like a 25 year-old condenser?
https://www.youtube.com/watch?v=r_em9lm69HQ, ancient receiver/drier?). I would get it checked out and flushed recharged before adding more fannage.
And yes, I used to have a W201, with always adequate AC, in the swelterpit that is SEC country.