Use the cheaper, straigh-forward 134-A and avoid the stuff with all the goop in it. Also, to make the gas go into the system faster, sit it in a bowl of warm water. A good way to know if you are getting the right amount in is to check pressure like you're already doing, but also to put a small thermometer in the center vent (close all other vents) and with the A/C on recirc. and on high, you're getting about 40degrees F.
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon. My cars have been running so well lately they've got me worried.