Typically, with this type of service, the coils are totally immersed in a dip coating process prior to the assembly of the unit. This particular coating system has a good reputation and is well known throughout the industry. However, after one year, the cooling circuit on this unit failed and is in need of replacement due to numerous leaks in the copper tubing.
The problem is, even though the entire condenser and evaporator may be covered with an effective coating system, the coils must ultimately be soldered into the copper cooling circuit. This results in sections of the tubing being exposed to the atmosphere.