Ac not cold

I have a 2014 Passat with a 6 speed manual (CKRA), the ac is not that cold even if I run it for hours. And the previous owner lost the sticker for how much freon goes into the system. I've looked into it and I'm seeing different amounts of freon to put into my car, and a some people have been having the same problem as me and there hasn't been closure on the posts. Both my fans spin and it also feels like the fan speed isn't as fast as other cars. Is there a common problem that this car has with the ac system?