The evaporator coil for a friend's central air conditioning is leaking condensate on the basement floor; however, the drain line is unobstructed and also flowing water.
This is a Carrier unit of unknown vintage, and it was installed with the access panel less than a foot from the basement wall, presumably because the refrigerant connections are right below the panel, and it's a direct shot from there to the outdoor unit. Whatever, it was a real pleasure taking the panel off and getting it back on.
Could not see much with the access panel off because of the restricted view, but I did see that the copper drain line was covered with water droplets. The drain runs from the "front" of the evaporator housing to the back where the drain hose connects. Thus the drain line runs through the inlet air plenum.
Noticed a small cover on one corner of the evaporator housing. Behind the cover was a very short drain pipe with a rubber plug in it; from the factory it appears. What is the purpose of this second drain connection? It connects to the same reservoir as the other drain, but a fair amount of water came out of it when I took the plug out.
I'm guessing that the condensate tray could have a leak in it, but I don't see any easy way of accessing it short of cutting a hole in the housing. I don't know what these trays are made of or if they are are prone to rusting out.
Alternatively, I'm wondering if the uninsulated drain line, which has cold condensate flowing through it, is condensing the humidity of the incoming air and that is what is leaking out of the nearby joint between the evaporator housing and the furnace housing that it's mounted on. That's where the water is showing up when the unit is operating. The existing drain line has a trap in it so there is no air flow through it.
My first thought is to put insulation on the drain pipe inside the evaporator housing, but it will be exceptionally difficult to reach. My second thought is to plug the present drain and install the hose on the presently unused drain so that there will be no flow in the uninsulated section and no condensation on its outside surface.
What do you suggest?