How do you switch from r134a freon to r414b freon?

The manufacturers claim that R414B refrigerant (Freon is a registered trademark of Dupont, and it's only actually Freon is manufactured by Dupont) can be used as a replacement without modification and with the same PAG compressor oil. While, personally, I remain a bit skeptical of this claim, a look at the operating pressures of 414b vs. 134a gives no indication that a 134a system wouldn't be able to handle 414b. However, you cannot blend the two - you would have to have the R134a evacuated and recovered out of your system, then put in the R414b.