I have to jump in here , Steve was correct with his saying that a DIYer who doesnt know the high side from the low has no reason messing with this system. Here is why . I worked for a ( mechanic) who had his own shop ( shadetree) when I was in high school. He payed me to pull engines ect. To the point , he was charging a system one day on a car and we heard a loud (pop). He didnt know his high side from the low on that certain car and he was charging through the high side when his quick charge bottle bursted. From then on he never worked on a car again due to he lost his left hand. From then on I took every precausion when working on systems whether it be SRS, or A/C. I love what I do and I want to do it until I die. But I dont want to be the fool that gets killed from stupidity, My advise if you dont know the system dont play with it . Money you can make to fix your car , but you cant fix what happens when you make that fatal mistake cause ( your not sure).