The AC quits working when the engine is idling. It works fine otherwise. HELP!! on 1999 Volkswagen Passat

This happens everytime the car stops at a stop light or any other time it is idling.

Radiator cooling fans not working properly! They need to be on with AC on. At road speed ram air does the trick, but when stopped the fans have to take over! This keeps the ac compressor from stopping due to high pressure from the heat. (My guess)