I have a 1996 Plymouth Grand Voyager 100k miles. When I bought it, the A/C was inoperable. I attempted to charge the system with a store bought charging system. The compressor wouldn't even start. I replaced the A/C relay switch and got the compressor going. I filled the system to the specs that the store bought recharging system recomended (25-45psi.) The front A/C started blowing relatively cool air but the rear A/C was still blowing warm air. I then noticed a sticker under the hood that mentioned the the car was equiped with a "High pressure refrigerant system." I was wondering what that pressure is for a dual (front and back) A/C system? I'm assuming that a store bought recharge will not have enough pressure to fully recharge the system?