I have got an older model Heil brand central heat & air split system. The size is 2 1/2 ton unit. My evaporator coil is leaking r22 refrigerant. I would like to replace it, but I have not been able to locate one to replace it with.

" but I have not been able to locate one to replace it with". Are you looking for an R-22 evaporator? I can only guess the system is pretty old. What is the SEER? Anything 10 or less is costing you money and I would replace it with a newer 410A system.