One issue I have with your after cooler is it is shaped like a coil in the upright position. An after cooler is shaped like a cars radiator/A/C condenser with the lines going side to side (lf and rt) with the air flow going down hill, as the air cools and condenses the water the water will run down hill and drop harmlessly into our tank or an inline drain before entering the tank. With a vertical coil the water can lay at the bottom of each coil wrap which can get reheated and pushed to the next coil wrap lying there till it can get reheated and possibly enter the tank as a vapor again. I would look at the design of the after cooler and see if you can change it to lye flat of remake another one in the shape of a square with the flow doing down hill.
I would bet there is water lying at the bottom of each coil wrap.
I would bet there is water lying at the bottom of each coil wrap.