Sent out for a "water leak from AC" call today at a pool supply company (heavy rains the last couple of days). Payne AHU, two years old. Ductwork dry, condensate trap and tray clean, charge and filters good. Note the corrosion on rook decking above flex duct. Holes are completely through the decking in numerous locations at store. All t-bar grid and diffusers in store corroding due to chlorine in the air from pool chemicals. AHU's replaced 2 years ago because evap coil fins completely disentegrated. Would you trust walking on the roof? Insulated start collar to cover my a** while there.