How I cleaned my window unit after a season of black gunk - steps that actually worked

I recently spent an entire Saturday cleaning the evaporator unit on my old slider AC, and it was definitely a deep clean job. I was worried about the internal structure, but thankfully the metal frame held up fine without any serious corrosion. The hardest part was getting into the blower wheel itself, which was absolutely caked in a grime I didn't recognize. I used a small, stiff nylon brush and a mixture of dish soap and a little vinegar to work the blades free. It took a lot of careful scraping beacuse the design makes the wheel really hard to reach. I followed the instructions to let it dry completely, which meant leaving the casing open for nearly 36 hours in a garage with a dehumidifier running. It felt like overkill, but I figured since the original post emphasized drying, I should just overdo it. When I finally put it back togather, the difference in airflow was imediately noticeable. It feels like it's drawing fresh air much more easily now that the sticky residue is gone.

Check the drain pan and the little drain hole in it too if you're doing this. Mine grew the same stuff back within a month because the hole was clogged and water just sat there. Poked it clear with a wire and it's stayed clean since. I also let it run fan-only for a bit after reassembly instead of switching straight to cool, seemed like a smart way to dry anything I missed.

The condenser side gets ignored too, the outdoor half of the coil behind the grille. I pulled the shroud off a 12,000 BTU unit at my brother's place last spring and the outside coils were matted with cottonwood fluff, which is why it iced up every July. A soft brush and a garden hose with low pressure fixed it. If yours breathes clean on the inside but still runs weak, look out there before blaming the compressor.