My A/C unit has ducts that run to the second floor, into the attic, to feed some ceiling vents.
Today, after several days of brutal humidity, I noticed paint blistering, and in one spot bursting, around where the ductwork comes upstairs.
When we bought the house (also in the summertime), we noticed some blistering, and the inspector thought it might be from the roof. The seller replaced the roof, we had it re-inspected, and it was judged to be sound.
This water is in the same place. Since we hadn't had any rain today, I suspected it was the A/C, so I cut out the most-affected piece of drywall. Sure enough, there is an uninsulated metal pipe installed right up against the drywall, and the condensation is easily felt.
My question is: what can I do about this? For now, I've cut out the affected drywall and drilled a few other holes in affected areas, hoping to get some airflow through there at least.
But what should my near and long-term strategy be? Do I need to replace this metal section of pipe? (It looks like there's an elbow there; the space is not big enough for the plastic insulated flexible ductwork that we have downstairs). How can I prevent this issue from happening? Would a permanent vent into this space help?