Air conditioner coils should be cleaned several times a year, and the preferred method is to disconnect the power, take a hose out there, and give the dirt on that thing a good what-for.
To make home ownership just a little bit easier, I propose a system by which the air conditioner sprays itself.
AC unit will have a reservoir that collects rainwater and passively filters it (say, with a screen). It will also have a small bottle of cleaning solution hooked up to an electric pump that squirts a little bit into the water reservoir every so often.
When the reservoir fills, as long as the temperature is warm enough, this unit will take that rainwater and using a small unobtrusive sprayer system that consists of a water pump and nozzles built into the bottom of the unit facing up, spray-clean itself. No extra connections are required, as the unit is already connected to your electrical system.
The cleaning solution would be accessible through a panel in the top and could come with a standardized neck size to allow for brands of solution to fit into multiple brands of air conditioners.