Finally figured out why my Midea Duo stopped cooling my office

I had a similar scare with my 12,000 BTU Midea Duo last August. I started noticing the casing felt unusually hot near the back, and the compressor was making a stressed, high-pitched humming sound. When I finally pulled the side panel off, I found that the plastic hose had started to warp and sag right where it meets the main exhaust port. The humidity where I live in South Carolina definitely doesn't help. That damp lint mixture you mentioned turned into a thick paste in the ridges of my hose, too. It acts like an insulator for the heat that's supposed to be leaving the machine, which just speeds up the plastic degrading. I didn't wait for it to fail; I ended up reinforcing the bends with some high-temp HVAC foil tape from the hardware store. It's frustrating becasue these units aren't exactly cheap, and you'd think they whould use a more heat-resistant polymer for the internal ducting. Now I make it a habit to vacuum out the internal intake every few months with a shop vac to keep that airflow as clear as possible. Hopefully, that buys me a few more seasons before the compressor gives up.

I've been running my 14,000 BTU Duo in a dusty garage workshop for five years now, and when I opened it up last spring, the internal hose was actually pristine. My issue was the secondary condensate pump clogging up with dog hair and fine wood shavings. It caused a tiny internal leak that eventually shorted out the control board, wich I had to replace with a part from a donor unit I found locally.

Instead of focusing just on the exhaust, I started using a Shop-Vac on the intake vents every two weeks and installed a custom mesh filter over the back. I think the gunk people see in those hoses is often just moisture that hasn’t drained properly mixing with bypass dust. If you keep the internal drainage path clear and the intake filters clean, the heat stays within spec and the plastic doesn’t get brittle enought to collapse. It’s more about consistent airflow management than just heat cycles in my experience.

Man, those plastic clips on the casing are the absolute worst. I tried to peek at my hose last summer and ended up snapping two of 'em just trying to get the side off. It's like they don't want us fixing these things ourselves. I noticed my fan motor was rattling like crazy before I even checked the hose. Turns out the heat from the blocked exhaust actually softened the plastic motor mounts too. If you're already in there, might as well tighten those down or you'll be hearing that drone all night. These units move a ton of air but they're built way too thin.

Quick update—I ended up replacing the unit since the compressor was fried. To the person who mentioned those flimsy plastic clips, you weren't kidding! I was way more careful opening the new one to inspect it first. I also checked the condensate pump like the workshop guy suggested; definately a spot to watch for hair and gunk early on. Thanks for the help.