What’s the best ways to clean box fans?

take them outside and hose them down. Make sure they are completely dry before using them again.

If you have an air compressor- Take it outside and use the air hose to blow off as much of the dust as possible. You'll be amazed to see how well this works! To get the tough stains that some times come from running this all summer, I use a paint stir stick wrapped with a wet paper towel or a antibacterial wipe. that should do it. Water on any electronic is a bad idea. Sorry.

My husband takes the fans out of the house. He gets the lawn blower out and blows them all CLEAN!!!

If they are in a barn. Spray Purple Power on them, let sit for a very few minutes and then spray down. Make sure they are DRY before plugging them in and turning them on.