I'm sure this has been asked a ton, but I just can't find it in the searches.
2001 AWW 1.8T Wolfsburg.
I bought some r134a and have a AC gauge that's a year old.
Here's what I did -
Car Running, AC on full blast, coldest setting. Compressor was visibly spinning.
I hooked up the gauge and it was right below Red, so I know it's not low. I added a little more but didn't want to overcharge it.
However, again, when I'm cruising going 80, it's really cold. But when the RPMs drop it gets warm.