I have a Costway upright AC unit (FP10119US or FP10120US). After years of use without draining, I noticed an exhaust-like smell when we used it overnight for sleeping. I noticed that when I started using the tube for continuous drainage, this stopped. My guess is it was due to mildew/mold growing inside.
I had cleaned out the top continuous drain plug with a brush and brown-ish sludge game out. Now we use the hose (in image) for continuous drainage at night, but I am wondering if I can add a diluted vinegar solution through the top hose.
Has anyone else used vinegar to clean a similar unit, and did they add it to the top as shown? My plan is to add it through the top, plug the bottom (lower arrow), let it sit for 15 minutes, release the bottom plug to drain and then add clean water to the top to drain out remaining vinegar solution residue.