both circuits tripping on low evaporator refrigerant pressure and I have been told that 5 tubes have been plugged, checked glycol concentration and it is 38% propolyne. going back tom. to start diggin. just wondering how do I find out the flow with added press drop caused by plugged tubes. Also there are no guages but there are 2 drains on bottom end bell but what are the chances they are ew and lw? any suggestions?