I have a 2000 Dodge Durango. By the way I am a newbie and thanks for having me. Anyway as the summer months are here I went and purchased an can to re charge my a/c. But when I tried to put it in the gauge would peg completely around to the other side. So I went back to the auto parts store and rented the gauges and pump to evac my system. Here comes the part where I am totally lost after making sure the system was empty I attempted to re charge the a/c once again by my surprise the system was pressurized again what the heck is going on? How do I get my system to stay un- pressurized so I can charge my system? What would cause it to pressurize ?