Last week I had my IR camera out to look under a 2nd story bathroom that had a known issue.
As I was walking away from that, I caught a small cold dot above a closet. I thought that was an odd spot, given it was NOT under the bathroom.
Then I realized I’m under the upstairs AC unit that I had just tested. OK, I thought, it’s perhaps just the refrigerant line touching the ceiling drywall, but I couldn’t leave it at that. So I put a moisture meter on it and the spot was indeed moist. After more investigation, I realized the AC condensation line is leaking.
There were zero visible signs of a leak.
Given it’s not summer, it would be several more months before anyone ran the AC with any regularity, so it would have been a while before it leaked enough become visible.
(And before anyone asks why I was testing an AC system in February, I am in Los Angeles, it was in the high 70’s that day).