I'm new to chillers so bare with the stupidity. This chiller appeared low on charge [r134a] the cooler barrel has a sight glass , you can see the freon flashing off but no liquid level like the one next to it . I had about 13 subcooling , pressures were good , very low sh 3, the condenser liq. Level valve was about 37% set for 50 . Not sure what that means , wondering if there's any bulletins on charging procedures , thanks for any help in advance .