1. Recover the R-22 refrigerant from the system.
2. Replace the TXV with one designed for R-410A.
3. Replace the mineral oil with POE oil.
4. Install adapter fittings in the discharge line to accommodate the R-410A fittings.
5. Replace the expansion valve.
6. Check for leaks and repair them if necessary.
7. Add R-410A refrigerant to the system.
8. Test the system and make adjustments if necessary.
Remember, this is a complex and potentially dangerous procedure. It's recommended to hire a qualified HVAC technician to perform the conversion.
