Corrosion is arguably one of the major reasons for expensive HVAC replacement. It affects all HVAC systems regardless of geographical location, but tends to be even more of a factor for HVAC units located along the seacoast.
Everyone in the industry knows that coil cleaners are a dime a dozen. They can be bought in gallon containers, 55 gallon drums, and everything in between. There are acidic, alkaline, foaming, penetrating, even so-called GREEN versions. But the biggest concern I have heard from HVAC professionals regarding coil cleaners is their portability.