A lady called myself and others because she thought that she heard noises in the ductwork, and a lot of times noises in the ductwork can be explained by the movement & shifting of the ducting itself, then just because you hear noises in the ductwork, does not mean that you have a concern with mice or rats or other indoor vermin… My corporation handles lots of heating & air conditioner repairs & I’ve only seen infestations a few times; Each a single of those times was a separate occasion that was even worse than the first! When I received a call from the residential customer, I knew that she was expecting myself and others to evaluate the ductwork; I took all of the items necessary to handle the task. I have a special camera at the end of a flexible stick & I use that camera to view the inside of the duct work throughout the house. It’s a superb way to see inside of the ductwork without taking anything apart. I searched all over the duct work for numerous minutes. I did not see any evidence of mice or rats anywhere, although I did see some evidence of droppings. It’s strenuous to tell if those droppings are outdated or new, so I told the owner of the condo that she should call an exterminator just to be safe if she was feeling worried. I did not want to be wrong about the mice or rats, although I was pretty certain that she did not have an infestation, then the noises absolutely came from the air conditioner or creaking floorboards in the house.