Can you add R-22 into a R-417a system?

No, you should not mix R-22 with R-417A in a refrigeration system. R-417A is a blended refrigerant designed as a retrofit option for R-22 systems, but it contains different properties and pressures. Mixing refrigerants can lead to system inefficiency, increased wear on components, and potential damage. It's best to either fully convert the system to R-417A or use only one type of refrigerant.