My wife wants the water and air filters in the fridge changed any time the light lights. I don't think they do much of anything myself, especially the air filter. The standard water filter is nearly $50 but I did find an off brand that is about $20. It's easy to change, the air filter requires a minor contortion, or emptying half the fridge.
Our HVACs were behind a rather heavy "door" that I had to wrestle away from the mountings to change the air filters. We had a guy doing some work and I asked him to mount the door on hinges, problem solved. Now they just open easy as Pi. The guy was depopcorning our lower level offices, which still had the old ceilings. We weren't around for that fortunately. They did clean up pretty much.