Wondering what is the best way to test the feed / drain valves on the flash tank. Have a chiller, circuit 2 only, running for 5 mins or so then failing on low discharge superheat. The valves are the upgraded ones, but still think they are faulty. While circuit was running, pulled the plug on drain valve, expecting valve to shut off and start filling up the flash tank, but if anything, it slowly dropped. Tried this same test on circuit one which is running fine and tank did fill up. Have had level come up to sight glass around the 35-40% mark. Level sensor seems o.k. Refrigerant charge is o.k. Recently removed by another tech to replace damaged sensor. Refrigerant weighed back in. Suction superheat is also running a little high. Is there any info out there on testing the valves. Thanks.