I haven’t turned on my AC all summer but have a lot of water on the floor around it. I have a condo, and there’s an identical upper unit with the HVAC right above mine. My water problem seems to coincide with the start of them using their HVAC this summer. I know I’m not isolated from issues in their plumbing room, because when they replaced their hot water tank a couple of years ago, some water came down through the chute into mine. The power company checked my outside unit and said the freon level was fine. He believed it had to do with the coils in my inside unit probably being rotted. But if I’m not running anything, how could this be the issue? I believe it’s related to the upstairs unit being run, but looking for more feedback and insights from someone who knows a lot more about this than me.
Rotted coils shouldn’t cause any water to go where it shouldn’t. A low refrigerant level could cause a coil to freeze over but really shouldn’t cause any water to overflow unless you have something like a plugged condensation line or a leak in the condensate pan. You mentioned inside unit so it sounds like you have a split system. If it’s in an attic you have a primary drain and a secondary drain pan and additional drain line under system. The secondary drain pan is a safety to catch the condensation from the air conditioner if the primary drain gets plugged. If the secondary and primary drain are plugged you could get condensation spilling out of the secondary pan and eventually on to your ceiling.