If you have a window air conditioner, chances are you've also had to deal with pigeons at some point. Pigeons love to roost on top of air conditioners, and their droppings can damage the unit and create an unsightly mess. There are several things you can do to deter pigeons from roosting on your air conditioner.
Cover the unit: One of the simplest ways to deter pigeons is to cover the air conditioner when it's not in use. You can buy a special cover made for window air conditioners, or just use a sheet or tarp. Be sure to secure the cover so that it doesn't blow off in windy weather.
Install spikes: Another option is to install spikes on top of the air conditioner. This will make it uncomfortable for pigeons to land, and they'll eventually give up and find somewhere else to roost. You can buy ready-made bird spikes at most hardware stores, or make your own out of wire or PVC pipe.
Use ultrasonic devices: Ultrasonic devices emit high-frequency sound waves that are imperceptible to humans but very annoying to birds. These devices can be effective at deterring pigeons, but they must be properly positioned in order for them to work well.
Whatever method you choose, be sure to take action before the pigeon problem gets out of hand. A little prevention will go a long way in keeping your air conditioner free from these pesky birds!