AC unit for VW's

If a four-year-old car is low on charge, there is a leak that must be diagnosed and repaired first, otherwise the new refrigerant will leak out right away. If you aren't familiar with working on AC systems, working with refrigerant is best left to the professionals. It can freeze eyeballs and cause frostbite. Professionals wear gloves and safety glasses at a minimum, and most wear face shields.