I am certified to do ac work, adding a few lbs of pressure is no where near adding an ounce of straight refrigerant. A FULL large can of the stuff you buy at the parts store is 16oz. Those small cans are 8. While 8oz is too much to add on your own, a few trigger squeezes is to see if you get cool air is ok. I do a 3 second trigger pull and then check. If by 4 trigger pulls you do not have a "working" system, STOP and seek help.