I've lived in my building for over four years and have had A/C all that time in my window. Today my super (great guy, but limited English) came and tried to explain to me that if you have an A/C, then you need brackets, as per the management. I looked over my rent-renewal notice that I received the other day, and there is nothing in it mentioning this nor in a rider. I told the super that I needed something in writing and he told me to call the landlord's office. I've done this with serious issues and haven't gotten anywhere with them.
Anyone else have experience with this? Perhaps an A/C fell out and the landlord got scared. Or he's trying to get ready to sell by bringing the place up to code. There were some "improvements" to the overall building, mainly cosmetic.