Okay guys... first things first....with the engine OFF turn the front portion of the AC clutch by hand. If you cannot easily do this by hand. Start shopping for a Compressor/clutch, accumulator and orifice tube. Second. when charging the AC should be on with the engine running. Also you cannot get the charge ports mixed up as they are different sizes. It will not allow you to physically enter the system through the high side with a parts store can. If you could and tried to you could send pressure back into the can possibly causing personal injury. also be sure to NOT use refrigerant cans labeled WITH sealant. Probably one of the worst and costly things you could do to your system.
now that's knocked out... Why are you adding more refrigerant? If it leaked out, think about this. If you have a hole in your radiator hose, would you fix the leak or just keep adding water or antifreeze? refrigerant is getting expensive. your system also has oil in it that will travel through the system with the refrigerant. That could give you an idea where the leak is when you find the oily residue on a fitting or a hose rub.
Also if the refrigerant has leaked out... air has seeped in. air has moisture in it. Moisture and refrigerant create an acid in the system and eat the system up from the inside out. You will need the system to be placed under a vacuum to ensure a fully sealed system as well as ensuring all moisture and air is removed. when a system is PROPERLY charged it is under a vaccum because air is non condensable and could create a high pressure situation that your system cannot tolerate and also would prevent heat transfer due to not enough refrigerant in the system.
R134a systems have pretty tight tolerances and ambient conditions also need to be considered for optimal performance. Magic number is the low side pressure readings. You would like to see about 28 psi or a little higher ... maybe 34. under 28 your evap will turn into a snowcone machine and prevent airflow. higher and it will cool, just not at its best.
Another tip. After you know you have an optimal system, ensure you have a good fan clutch or an electric fan wired to a pressure switch on the compressor of the AC system. R134a needs about 20-30 degree temp drop at the condenser. improper cooling at the condenser is why R134a stinks in the south during the summer.
Over 10 years in the Automotive AC field with another 7 in commercial and residential refrigeration. So if you have any question please feel free to contact me and I can give you some help.
Matt
