2014 Subaru Legacy, 122k miles.
My AC drain backed up and flooded the passenger side floor. I opened the hood and saw that I could reach the tube from above. I tried a small drain brush and a zip tie, neither worked. So I pulled back the carpet, removed the glove box and tray that was underneath it. Then I unplugged the hose from the AC coil compartment.
The hose had a thick tar like substance clogging the hose. It was black and a bit fibrous and sticky but not greasy. It was exactly like that non hardening sealer made of tar and fibers. I eventually got enough of it out so that water can flow through the hose, but I didn’t get it all out.
I wonder what it is and where it came from. BTW, it was not at the mouth of the hose but about 2" from the top and I estimate that it was about 3" long based on squeezing the tube before I finally got some of it out. I got some out using hot water, a 36 tie staip and some detergent. The dish detergent was a lubricant to help push the tie strap down through the hose.