1. Pressure Washer
Pro – As the name suggests, this tool has great pressure, so dirt and buildup come off pretty well. Too well actually. It also makes great artwork in coils.
Con – First, it can only be used outside, unless you like dealing with insurance companies and irate customers. Unfortunately, this tool has a little too much pressure and can easily damage and bend the fins of the unit. Coil fins in most air handlers are made of thin aluminum or copper that are sensitive to high pressure and can bend or flatten easily. Too much power could crush coils flat. While some people like to stand back and still try to use one, that just means that no water will get through the coil either. Bad idea.