The issue might be that the inline thermometers are un-precise. You have to use a needle thermometer, and it has to be the same one, keep in mind that if one is 1 degree F off, you might be off by 20%. The same must be said for top mounted buffer tank temperatures, which usually lag behind. The differential is not the delta T!. The temp might lag behind and will likely off by a few degrees. So your temp sensor indicates 50F, but your tank is maybe 40F, which means the leaving water t amp might be 35F. In order to get the temp down to 35F, the wall of your heat exchanger might be 28F, and ice starts to form, on the walls of the heat exchanger, indicating a lot pressure and a large pressure drop, which you think indicates a lot of flow, when in reality you have not enough flow. I do have enough scar tissue with sensors and thermodynamic inertia, and sensors lagging behind. 1) Get a needle thermometer. Measure temp in and out at the load side. measure flow and temp without the compressor running. Let us know the numbers. What model numbers do you have? 036 and 060?