Hi is this the secondary pan under the unit ? If so its probably due to the primary drain being plugged up , and the pan is catching the over flow, let me know
So where is the primary pan and where does it's condensation go?
Hi, in a typical set up the coil pan itself which is located in the air handler has a pan, it should have a drain pipe connected to it, usually a 3/4" PVC pipe ( white but sometimes black ) , that is the primary drain, the pan that is under the entire unit which I believe is what we are talking about being full of water is the secondary pan, that one should have no water in it. Let me know if you see this other drain pipe,
If I can refer you to this picture the line that the man is working on is the drain pipe, yours may be on its side if its in an attic or crawl but you will definitely have it.