I will assume you are not a licensed HVAC person and therefore do not have the EPA license for handling R-22. If that is the case you will need a HVAC company to install your condenser. I would interview 3 companies and ask them if your current evaporator coil can be used. The problem usually is removing all the R-22 oil since the newer R-410 uses a different, incompatible oil. You will want the installer to warranty everything and, sadly, that may include you buying a new coil. My only words of consolation are coils are not expensive.