3
questions

where and how to add freon to 1990 coupe quattro

I have a problem with the brake system I replaced the brake accumulator and the master cylinder, but the brake pedal is hard and difficult to stop, I haved to press hard and lock the brakes up, so vibration from the anti-lock system occurs. This is a hydro boost brake system so the boost comes from the power steering.

and how can I replace it?