I personally am not familiar with 409 so I don't have an opinion on it's use. Having said that epa has not approved 409 for use in vehicles to my knowledge.
"Many refrigerants, including R-401A (made by DuPont), R-401B (DuPont), R-409A (Elf Atochem), Care 30 (Calor Gas), Adak-29/Adak-12...