Um... yes. If the coop is accessible from the run, and does not close securely against predators you are asking for trouble. You should be able to completely close the coop at night with locks that a five fingers raccoon can not manipulate to open. They have hands, not paws. That includes oppose-able thumbs.. Chicken wire is not safe for the keeping raccoons out. If you have an open air coop with hardware cloth and that hardware cloth is secured properly, then really shouldn't have a problem... Is that what you mean by open coop? Or do you mean, the coop door/pop door is open?