If it is a classical type of aircon try to feel with hand as to where you have were hose pipes hot and where its get cool...or less warm most off, it could be that the dryer bottle is full, and need to be replaced ( especially when you had a leak... gas went away humid air replaced it...
https://workshop-manuals.com/audi/a4_mk1/power_transmission/5-speed_manual_gearbox_01a_(4wd)/technical_data/gearbox_identification/
find you pic here as where the indication/ratio is on the box itself
Paul