I have not run my AC for at least two months - and suddenly today there is water (condensation?) dripping from just one of my ceiling mounted AC vents. It is an unusually warm day (60 degrees) and it was in the 30's last night - could this be the source? It is def coming from inside the flex tubing - not an external source. Any thoughts?
Where do you live. That is not an uncommon problem in colder areas. One of my customers has to plug all her vents with insulation to prevent hot humid air rising in there/condensing inside/and dripping back down. Plus you lose a lot of heat by air rising up to the attic thru the vents.