HVAC filter size
Renter here with no knowledge about hvac systems. Our AC wasn’t working last summer so the hvac technician came out and fixed it and also replaced the filter. I remember him saying the hvac system is really old and they don’t make the filter size it needs anymore. He put in a 14x24x1 FPR 7 in. I was looking at the filter today to buy new ones and saw the ripped, old yellow label with filter size info. Would it be safe to say the bottom filter is 13x27.5x1? Also, there is no other filter anywhere and from what I read the internal side is the filter for the return air grille. Posting picture of what the return air grille currently looks like. There’s a bunch of dust and crap in there. Should I open it and clean it out? I want to have AC but also clean air! Thanks for any advice!