Puron vs Freon

I am replacing my old air conditioner with a high efficiency model.

The old unit uses Freon (R-22), the new unit uses Puron (R-410A).

The compressor and evaporator coil will be new. No problem. What concerns me, is the two pipes in the wall that run from the compressor to the evaporator.

Since Freon and Puron seem to be incompatible with each other, is it necessary to purge any remaining refrigerant/oil from the tubing? What is the proscribed procedure?

Just trying to keep an eye on the contractor. I am the one who has to live with the system.

Thank you.

Purging/cleaning the line set would be a bare minimium. Sure do not know how a person could guarntee that everything was cleaned out with out a lot of testing. I would run a new one if it was my install. Reusing old has proven to be a problem for me in the past. I do know of companies that do it. Is the old line set big enough for the new unit? In the end the installer is the one that makes or breaks the preformance of the equipment.