My ac drains to my upstairs sink. I have lived here for 5 years and have new issue with condensation on black ac drain pipe under sink upstairs. There is additional condensation on 3 inch drain pipe which runs from upstairs to the main drain leaving the house. This condensation is on pipes between garage ceiling and 2nd story floor. I have had plumbers clear the line and I've had several ac people just say, "that's normal, you will have condensation". Doesn't seem right. I haven't had condensation for 5 years and no one else in neighborhood is having these condensation issues. Home is 8 yrs old.
Thanks for any suggestions.
Chris

What is the humidity level in your home ? A high humidity will cause increased condensation. Have you checked the toilets for leaking flappers ? That will also add to the condensation on the 3" pipe. Adding insulation to the ac line will probably help a little.

You must have some additional problem, because the small amount of A/C condensation water could NOT cause condensation on a 3" line.

You have recently smashed all state records with your rainfall amounts so you are removing far more humidity/moisture this season than past seasons. That alone will produce the results that you see.

Sounds like the "Snot" in the lines could be causing your problem. You need to flush out the condensate line and soon...Bleach is a good idea to clean up the pan under your unit AFTER YOU HAVE CLEARED OUT THE SNOT!