I had to ask my apt management to take a better look at our split AC units. Turned out, they needed to be cleaned around every 6 months. I’m not taking about simply cleaning the screen, but they had to get HVAC people to come and pump out dirt with water. I’ve been in my apt for 6 years and this was the first time it was done. When I moved into it, the previous tenant was here for 3 years. It’s gross.