Too many air filter options

must admit that my partner does way more around the condo than I do.

Of course, I do lots of housework and laundry and cleaning, and but my partner Billy does all of the condo improvements and all of the repairs around this place.

For instance, Last month, out cooling system stopped entirely working for some odd reason! There was just warm air coming out of all the air vents and the condo just wasn’t cooling down. We had the cooling system turned all the way down on the control unit, but nothing was happening. So, Billy went down to the heating system room in the basement to see if he could figure out what the issue was with the cooling system. I heard him messing around with the central cooling system in the basement, and there still wasn’t any cold air coming out. However, Billy called up the stairs to get me to come down from the living room. I went downstairs to the heating system room and Billy was holding up an old gross looking air filter. It was gray with dust and dirt and it looked like it was completely blocked up. Billy said that it was no wonder that there was no cooling going on with our cooling system unit, Billy wanted to work on cleaning out and blowing all the dust and dirt out of the cooling system program and so he wanted me to go to the hardware store to get a new air filter for the cooling system. I left to go to the store, but when I got to the heating and cooling system aisle, I saw that there were dozens of filters that would fit our cooling system unit. I had no idea which air filter to get.
Cooling expert