Hello, I have an older Ruud air conditioning system in my home, it has the model RCHA-36A2GG17XI Air Handler unit installed and the evaporator coil in this unit is seriously corroded and leaking freon. Are there any interchangeable Air Handler units that can be installed in its place? Thanks for your help.

The air handler is just a fan, not the whole unit. Any older 3 ton evaporator should work as long as it is refrigerant compatible and fits in the plenum. Many smaller non national HVAC companies should able to help. I have mixed different condensers and evaporators with no issue.