A House Sparrow has rented the lower section of the A/C. According to Jim Wright - The Record's birding expert - "they love to nest near air-conditioners......You have one popular place".
BTW - that scraggly material in the photos is the remnants of a piece of carpeting that was glued to the top of the A/C casing 23 years ago to soundproof it from the noise that heavy rain makes on metal.
I slept well on rainy nights for about 2 years.