Oops, I forgot to add that, Ron! Silly me - yes, it has been critical to keep dust out of the fan. We tack up those cheapy furnace filters, the ones that look like chicken wire and paper that you can almost see right through. Cheap and cheerful!The fan should work just fine.
If pulling air out of the coop, I would set up a makeshift filter, as a coop environment can be very dusty, and not beneficial to electric motors.