I have a custom made cupboard that my heating and cooling unit is in. The heating and cooling component is separated by various odd parts in the cabinet, and it has a door for easy access to the Heating and A/C unit for myself and Heating and A/C professionals; Anyways, well I think left the door open for a bit too long, because when I was out getting the mail, I noticed a bird landed in my Heating and A/C plan and disappeared someplace, but i came closer to inspect, and I noticed that various birds had made a nest out of an Heating and A/C cabinet. Thankfully the part they chose was the part that was separated away from the actual gas furnace and cooling system, so my Heating and A/C component would be okay and the birds would be too, then usually I would just shoo the birds away, but they already had eggs, and I didn’t want to risk scaring them away and killing potential life! So I decided since they weren’t harming anything to just leave them there. Thankfully since birds grow entirely fast, the babies were there for only a little over a week, before they became fledglings and took flight. After the birds successfully cleared out, I detachd the outdated nest and cleaned the inside of my Heating and A/C machine and then shut the door to prevent them from coming back. I honestly still see the same birds every now and then, some of them now with their own families, and I am glad I made the decision to leave them alone rather than detach them.