Coil Leak - Old Coil Used with New Condenser?

[houstonmarc]

My house has a staged system, 2 condensers, 2 coils. Main unit works fine.

Second staged unit is a builder-grade 10SEER Rheem Corsaire 3 ton condenser (10AJ series) installed in 2006. It loses charge after about a month. Technician says leak is in the coil at the furnace.

The coil it seems to mate with looks old on the outside. It also looks like a new set of copper lines was run from the condenser to the coil when it was installed, the prior set which is enclosed in the roof was abandoned for a set that runs over the roof to the mechanical room.

Is it possible an old coil was re-used when the unit was installed? Prior owner left only paperwork for the condenser warranty (5 years) and nothing on the coil. The installer appears to be out of business.

Thoughts on this set-up? What's the chance of the coil being under warranty?

[classical]

You have not provided enough information, we would need model and serial numbers of the coil and condenser. It is very likely that the old coil was retained and a new condenser installed. The coil may have a part warranty but you would need to pay for labor and any ductwork modifications if needed.