Currently using 2 Shark vacuums, one blows hot air and sounded awful, the other blows dog and smells air (we have 2 dogs). Cleaning or replacing filters is imperative. Cleaning them isn't difficult, but it's not fun either, and they need to dry. I've done this several times semi-effectively. I put new ones in and both vacuums have improved. The one that was struggling (and blowing hot air because the engine had to work harder) now sounds fine and blows cold air like it should. And the other vacuum cleaner no longer blows dog-smelling air. Overall very satisfied. I wish I had done that sooner.